201 results on '"de Leenheer AP"'
Search Results
2. Investigation of the quantitative properties of the quadrupole orthogonal acceleration time-of-flight mass spectrometer with electrospray ionisation using 3,4-methylenedioxymethamphetamine
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Clauwaert, Van Bocxlaer JF, Major, Claereboudt, Lambert, Van den Eeckhout EM, Van Peteghem CH, and De Leenheer AP
- Abstract
This paper describes the investigation of the potential of a quadrupole orthogonal acceleration time-of-flight mass spectrometer (Q-TOF) equipped with an atmospheric pressure ionisation interface for quantitative measurements of small molecules separated by reversed phase liquid chromatography. To this end, the detection limits and linear dynamic range in particular were studied in an LC/MS/MS experiment using 3,4-methylenedioxymethamphetamine standards and 3,4-methylenedioxyethylamphetamine for internal standardisation. In a second phase, the experiment was repeated with real biological extracts (whole blood, serum, and vitreous humour). A calibration for 3,4-methylenedioxymethamphetamine and its metabolite 3,4-methylenedioxyamphetamine was prepared in each of these matrices again using 3,4-methylenedioxyethylamphetamine as internal standard. The resulting quantitative data were compared with those obtained by liquid chromatography with fluorescence detection for the same extracts. The Q-TOF results revealed excellent sensitivity and a linear dynamic range of nearly four decades (2-10 000 pg on-column, r(2) = 0.9998, 1/x weighting). Furthermore, all the calibration curves prepared in biological material were superimposable, LC/MS/MS and LC-fluorescence, and the quantitative results for actual samples compared very favourably. It was concluded that the Q-TOF achieves a linear dynamic range for quantitative LC/MS/MS work exceeding that of fluorescence detection and at much better absolute sensitivity. Copyright 1999 John WileySons, Ltd.
- Published
- 1999
3. Longitudinal study on the prevalence of benzodiazepine (mis)use in a prison: importance of the analytical strategy.
- Author
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Borrey D, Meyer E, Duchateau L, Lambert W, Van Peteghem C, and De Leenheer AP
- Abstract
AIMS: This study evaluates the suitability of gas chromatographic-mass spectrometric (GC-MS) analysis to follow-up the extent of benzodiazepine (mis)use in a Belgian prison population and compares it to other analytical strategies (e.g. screening followed by confirmation of the positive samples). DESIGN AND PARTICIPANTS: From February to August 1998, 598 persons were jailed of which 188 (31.4% of the incoming detainees) volunteered to be screened. Urine samples (530 in total) were collected on the day of arrival and after 14, 30 and 90 days of imprisonment. MEASUREMENTS: All samples were screened by EMIT(R) for benzodiazepines and analysed subsequently by GC-MS. FINDINGS: EMIT(R) screening yielded 117 (22.1%) positive samples, a number which increased to 174 (32.8%) after GC-MS analysis. Of these 174 GC-MS positive samples, 119 (68.4%) contained one benzodiazepine while for the remaining samples multiple benzodiazepine (mis)use could be demonstrated. A significant increase in benzodiazepine (mis)use was indicated only from day 0 to day 14 based on the GC-MS results but not on the immunoassay results, even when the latter were complemented with GC-MS analysis of the positively screened samples. The GC-MS data also demonstrated that benzodiazepines are mainly (mis)used by subjects on benzodiazepine prescription as almost 50% of these subjects took additional non-prescribed benzodiazepines. During GC-MS analysis other drugs were co-extracted unintentionally and chromatographed and 23.9% of the volunteers were positive for illegal drugs on the day of arrival. CONCLUSION: Immunoassay results yield an underestimation of the problem of benzodiazepine (mis)use in prison due to the high false negative rate. GC-MS analysis of all samples therefore is the recommended strategy for this type of longitudinal study as it yields more correct and detailed information than the immunoassay results. [ABSTRACT FROM AUTHOR]
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- 2003
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4. Gas chromatographic determination of iproclozide in urine of psychiatric treated patients
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Claeys Ae, De Leenheer Ap, and de Sagher Rm
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Chromatography ,Chromatography, Gas ,Hydrazines ,Monoamine Oxidase Inhibitors ,Dose-Response Relationship, Drug ,Chemistry ,Humans ,Urine ,Analytical Chemistry ,Glycolates - Published
- 1975
5. Class identity assignment for amphetamines using neural networks and GC-FTIR data.
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Gosav S, Praisler M, Van Bocxlaer J, De Leenheer AP, and Massart DL
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- Chromatography, Gas methods, Reproducibility of Results, Sensitivity and Specificity, Spectroscopy, Fourier Transform Infrared methods, Amphetamines analysis, Central Nervous System Stimulants analysis, Neural Networks, Computer
- Abstract
An exploratory analysis was performed in order to evaluate the feasibility of building of neural network (NN) systems automating the identification of amphetamines necessary in the investigation of drugs of abuse for epidemiological, clinical and forensic purposes. A first neural network system was built to distinguish between amphetamines and nonamphetamines. A second, more refined system, aimed to the recognition of amphetamines according to their toxicological activity (stimulant amphetamines, hallucinogenic amphetamines, nonamphetamines). Both systems proved that discrimination between amphetamines and nonamphetamines, as well as between stimulants, hallucinogens and nonamphetamines is possible (83.44% and 85.71% correct classification rate, respectively). The spectroscopic interpretation of the 40 most important input variables (GC-FTIR absorption intensities) shows that the modeling power of an input variable seems to be correlated with the stability and not with the intensity of the spectral interaction. Thus, discarding variables only because they correspond to spectral windows with weak absorptions does not seem be not advisable.
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- 2006
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6. Evaluation of a candidate reference measurement procedure for serum free testosterone based on ultrafiltration and isotope dilution-gas chromatography-mass spectrometry.
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Van Uytfanghe K, Stöckl D, Kaufman JM, Fiers T, Ross HA, De Leenheer AP, and Thienpont LM
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- Blood Proteins metabolism, Gas Chromatography-Mass Spectrometry standards, Humans, Indicator Dilution Techniques standards, Male, Protein Binding, Reference Standards, Reproducibility of Results, Testosterone metabolism, Ultrafiltration standards, Testosterone blood
- Abstract
Background: To assess the analytical validity of free testosterone (FTe) measurements, a reference measurement procedure (RMP) is required. For steroids, isotope dilution-mass spectrometry is accepted as state-of-the-art technology. Because FTe is defined as the hormone fraction in serum water in equilibrium with the protein-bound fraction, the RMP should include a physical separation step. The use of equilibrium dialysis (ED) or ultrafiltration (UF) is advocated. Our objective was to develop such a candidate RMP., Methods: We selected UF combined with isotope dilution-gas chromatography-mass spectrometry (ID-GC/MS) for direct measurement of Te in the ultrafiltrate. After optimization of the UF process, the complete procedure was validated by use of split-sample comparisons with indirect ED (iED) and symmetric dialysis (SyD)., Results: The candidate RMP gave maximum within-day, between-day, and total CVs of 3.0%, 3.1%, and 4.3%. The Deming regression equations for the respective method comparisons were: UF-ID-GC/MS = 0.98(iED) - 53 pmol/L (r = 0.94; S(y|x)= 42 pmol/L) and UF-ID-GC/MS = 0.92(SyD) + 21 pmol/L (r = 0.97; S(y|x)= 31 pmol/L)., Conclusions: We achieved the objective of a state-of-the-art candidate RMP, which agreed well with iED and SyD. However, we also demonstrated that a degree of discordance remains, which may require a decision from an authoritative organization on the recommended procedure to measure free hormone concentrations.
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- 2004
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7. Application of a C-peptide electrospray ionization-isotope dilution-liquid chromatography-tandem mass spectrometry measurement procedure for the evaluation of five C-peptide immunoassays for urine.
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Fierens C, Stöckl D, Baetens D, De Leenheer AP, and Thienpont LM
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- C-Peptide urine, Isotopes, Quality Control, Sensitivity and Specificity, C-Peptide chemistry, Chromatography, High Pressure Liquid methods, Spectrometry, Mass, Electrospray Ionization methods
- Abstract
This study applied electrospray ionization-isotope dilution-liquid chromatography-tandem mass spectrometry for the evaluation of five urinary C-peptide immunoassays via split-sample measurements. The immunoassays measured in duplicate in the same run, the comparison method in triplicate over different runs. From the data, the within-run imprecision and the method comparison total RSDs were calculated. Regression analysis revealed on the one hand systematic differences, on the other, an excellent correlation between the test and comparison methods. From the spread of the data around the regression line in comparison with the 95% prediction intervals from the total RSD, sample-related effects and/or specificity problems were apparent and investigated.
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- 2003
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8. Fatality due to combined use of the designer drugs MDMA and PMA: a distribution study.
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Dams R, De Letter EA, Mortier KA, Cordonnier JA, Lambert WE, Piette MH, Van Calenbergh S, and De Leenheer AP
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- 3,4-Methylenedioxyamphetamine pharmacokinetics, 3,4-Methylenedioxyamphetamine poisoning, Adult, Amphetamine pharmacokinetics, Amphetamines, Autopsy, Chromatography, Liquid methods, Drug Interactions, Fatal Outcome, Humans, Male, N-Methyl-3,4-methylenedioxyamphetamine pharmacokinetics, Spectrometry, Mass, Electrospray Ionization methods, Tissue Distribution, 3,4-Methylenedioxyamphetamine analogs & derivatives, Amphetamine poisoning, Designer Drugs poisoning, N-Methyl-3,4-methylenedioxyamphetamine poisoning
- Abstract
We present a fatal case involving the combined ingestion of amphetamine, 3,4-methylenedioxymethylamphetamine, 3,4-methylenedioxyamphetamine, and paramethoxyamphetamine. Various postmortem specimens (e.g., several blood samples, urine, and tissue samples) were analyzed to study the distribution of the compounds and their metabolites in the human body. Quantitation took place using liquid chromatography-sonic spray ionization-mass spectrometry after pretreatment with a liquid-liquid extraction. The medico-legal findings were compatible with a disseminated intravascular coagulation induced by hyperthermia caused by the simultaneous intake of the amphetamine analogues.
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- 2003
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9. Standardization of C-peptide measurements in urine by method comparison with isotope-dilution mass spectrometry.
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Fierens C, Stöckl D, Baetens D, De Leenheer AP, and Thienpont LM
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- Adolescent, Adult, Aged, Chromatography, Liquid, Female, Humans, Immunoassay, Indicator Dilution Techniques, Isotopes, Male, Middle Aged, Spectrometry, Mass, Electrospray Ionization methods, C-Peptide standards, C-Peptide urine
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- 2003
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10. LC-atmospheric pressure chemical ionization-MS/ MS analysis of multiple illicit drugs, methadone, and their metabolites in oral fluid following protein precipitation.
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Dams R, Murphy CM, Choo RE, Lambert WE, De Leenheer AP, and Huestis MA
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- Humans, Methadone metabolism, Proteins chemistry, Saliva chemistry, Spectrometry, Mass, Electrospray Ionization methods, Methadone analysis, Substance Abuse Detection methods
- Abstract
A quantitative LC-APCI-MS/MS method for simultaneous determination of multiple illicit drugs, methadone, and their metabolites in oral fluid was developed and validated. Sample pretreatment was limited to acetonitrile protein precipitation. LC separation was performed in 25.5 min, with a total analysis time of 35 min. Identification and quantitation were based on selected reaction monitoring. Calibration by linear regression analysis utilized deuterated internal standards and a weighing factor 1/x. Limits of detection and lower limits of quantitation (LOQ) were established between 0.25 and 5 ng/ mL and 0.5-10 ng/mL, respectively. linearity was obtained with an average correlation coefficient (R2) of >0.99, over a dynamic range from the LOQ up to maximum 500 ng/mL The method demonstrated good accuracy, intra- and interbatch precision, recovery, and stability for all compounds. No oral fluid matrix effect was observed throughout the chromatographic run. Protein precipitation provided a fast and simple sample pretreatment, while LC-APCI-MS/MS proved to be a sensitive and rugged quantitative method for multiple illicit and legal drugs in oral fluid. The method proved to be suitable for the evaluation of oral fluid as an alternative matrix to urine for monitoring illicit drug use and for determining oral fluid methadone concentrations in pregnant opiate and/or cocaine addicts.
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- 2003
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11. Analysis of flecainide and two metabolites in biological specimens by HPLC: application to a fatal intoxication.
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Benijts T, Borrey D, Lambert WE, De Letter EA, Piette MH, Van Peteghem C, and De Leenheer AP
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- Adolescent, Anti-Arrhythmia Agents poisoning, Chromatography, High Pressure Liquid, Drug Overdose, Fatal Outcome, Female, Flecainide poisoning, Humans, Anti-Arrhythmia Agents analysis, Flecainide analysis, Forensic Medicine methods, Suicide
- Abstract
A few days after her admittance to a hospital for a suicide attempt with benzodiazepines, a 15-year-old girl was found dead in bed. At autopsy, no specific anatomo-pathologic cause of death was identified. Systematic toxicological analysis (HPLC-DAD, GC-NPD, and GC-MS) of postmortem blood and urine revealed the presence of high concentrations of flecainide and its two major metabolites. Flecainide is a class IC anti-arrhythmic drug causing a decreased intracardiac conduction velocity in all parts of the heart. To identify and quantitate flecainide together with its metabolites in blood, urine, and other toxicologically relevant matrices, a new method was developed using high-performance liquid chromatography with diode-array detection. All compounds were separated on a Hypersil BDS phenyl column using water, methanol, and 1.5M ammonium acetate in a gradient system. Chromatographic analysis was preceded by an optimized solid-phase extraction procedure on RP-C18 extraction columns. The flecainide concentrations in blood and urine were 18.73 and 28.3 mg/L, respectively, and the metabolites were detected only in urine at the following concentrations: 9.4 mg/L for meta-O-dealkylated flecainide and 8.59 mg/L for meta-O-dealkylated flecainide lactam. Based on these results, it was concluded that the suicide was consistent with an overdose of this anti-arrhythmic drug.
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- 2003
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12. No compound a formation with Superia during minimal-flow sevoflurane anesthesia: a comparison with Sofnolime.
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Bouche MP, Versichelen LF, Struys MM, Van Bocxlaer JF, De Leenheer AP, Mortier EP, and Rolly G
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- Absorption, Adult, Aged, Carbon Dioxide chemistry, Female, Humans, Hydroxides chemistry, Male, Middle Aged, Potassium Compounds chemistry, Sevoflurane, Sodium Hydroxide chemistry, Anesthetics, Inhalation chemistry, Ethers chemistry, Hydrocarbons, Fluorinated chemistry, Methyl Ethers chemistry
- Abstract
Unlabelled: There is concern about the toxicity of Compound (Co) A. Absorbents differ in the production of Co A during minimal-flow sevoflurane anesthesia. Strong alkali-free Amsorb does not produce Co A. It was our aim to study Superia, another new NaOH- and KOH-free CO(2) absorbent, in minimal-flow anesthesia, compared with KOH-free Sofnolime. After Ethics Committee approval, 14 consenting adult patients were included randomly by using Superia or Sofnolime as the CO(2) absorbent in the compact 750-mL canister of an ADU ventilator. After propofol and remifentanil administration, sevoflurane was given in oxygen and air (500 mL/min; fraction of inspired oxygen, 0.4), aiming at an end-tidal concentration of 2.3%-2.5%; ventilation aimed for 33-35 mm Hg PETCO(2). Compound A inspired (Co A(insp)) and expired (Co A(exp)) samples were taken for analysis, and canister temperatures were measured for 150 min. Statistical analysis was performed with the Friedman test or the Mann-Whitney U-test where appropriate. Correction for multiple testing was used. In the Superia group, no significant amount of Co A was formed, whereas in the Sofnolime group, maximum median (range) inspiratory values of 25 ppm (16 ppm) were found. The intergroup difference was P < 0.05. No difference was noticed between the two groups for the canister CO(2) absorbent temperature., Implications: During minimal-flow 2.3%-2.5% end-tidal sevoflurane, no compound A (Co A) is formed with the NaOH- and KOH-free CO(2) absorbent Superia. Although Co A values with KOH-free Sofnolime are still within reported safe limits, Superia is definitely an alternative for safe clinical practice.
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- 2002
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13. Analysis of benzo[a]pyrene diol epoxide-DNA adducts by capillary zone electrophoresis- electrospray ionization-mass spectrometry in conjunction with sample stacking.
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Willems AV, Deforce DL, Van den Eeckhout EG, Lambert WE, Van Peteghem CH, De Leenheer AP, and Van Bocxlaer JF
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- 7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide chemistry, DNA Adducts chemistry, Electrophoresis, Capillary methods, Molecular Conformation, Spectrometry, Mass, Electrospray Ionization methods, 7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide analysis, DNA Adducts analysis
- Abstract
Benzo[a]pyrene diol epoxide (BPDE) was reacted in vitro with (2'-deoxy)nucleotides and with calf thymus DNA. The modified DNA was enzymatically hydrolyzed to the 5'-monophosphate nucleotides using deoxyribonuclease I (DNA-ase I), nuclease P1 and snake venom phosphodiesterase (SVP). Most of the unmodified nucleotides were removed using solid phase extraction (SPE) in a polystyrene divinylbenzene copolymer. Three adducts could be detected and identified using capillary zone electrophoresis(negative)-ion electrospray ionization-mass spectrometry (CZE-(-)-ESI-MS) in conjunction with sample stacking. This way, not only a BPDE-dGMP adduct [(M-H)(-) at m/z 648], a well-known nucleotide adduct, could be retrieved, but also a BPDE-dAMP [(M-H)(-) at m/z 632] and a BPDE-dCMP adduct [(M-H)(-) at m/z 608] could be detected for the first time. The presence of the prominent ion at m/z 195 (the deoxyribose-phosphate ion) in the three low-energy collision-activated decomposition (CAD) spectra indicated that the adducts were formed through base-alkylation. CZE-positive ion ESI-MS/MS experiments were performed to obtain further information on base-alkylation. The absence of the loss of NH(3) from the nucleobase in each CAD spectrum points to an alkylated exocyclic NH(2) position of the nucleobase. So, the three adducts could be identified as BPDE-N(2)-dGMP, BPDE-N(6)-dAMP and BPDE-N(4)-dCMP using CZE-ESI-MS and CZE-ESI-MS/MS.
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- 2002
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14. Simultaneous, quantitative determination of opiates, amphetamines, cocaine and benzoylecgonine in oral fluid by liquid chromatography quadrupole-time-of-flight mass spectrometry.
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Mortier KA, Maudens KE, Lambert WE, Clauwaert KM, Van Bocxlaer JF, Deforce DL, Van Peteghem CH, and De Leenheer AP
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- Humans, Reference Standards, Reproducibility of Results, Amphetamines analysis, Chromatography, Liquid methods, Cocaine analogs & derivatives, Cocaine analysis, Narcotics analysis, Saliva chemistry, Spectrometry, Mass, Electrospray Ionization methods
- Abstract
A method using liquid chromatography coupled to tandem mass spectrometry is described for the determination of drugs of abuse in oral fluid. The method is able to simultaneously quantify amphetamines (amphetamine, methamphetamine, MDA, MDMA and MDEA), opiates (morphine and codeine), cocaine and benzoylecgonine. Only 200 micro of oral fluid is spent for analysis. The sample preparation is easy and consists of mixed mode phase solid-phase extraction. Reversed-phase chromatography is carried out on a narrow bore phenyl type column at a flow-rate of 0.2 ml/min. A gradient is applied ranging from 6 to 67.6% methanol with ammonium formate (10 mM, pH 5.0) added to the mobile phase. The column effluent was directed into a quadrupole-time-of-flight instrument by electrospray ionization, without the use of a splitter. A validation study was carried out. Recovery ranged from 52.3 to 98.8%, within-day and between-day precision expressed by relative standard deviation were less than 11.9 and 16.8%, respectively, and inaccuracy did not exceed 11.6%. The limit of quantification was 2 ng/ml (0.66 x 10(-5)-1.48 x 10(-5) M) for all compounds. Internal standards were used to generate quadratic calibration curves (r(2)>0.999). The method was applied to real samples obtained from suspected drug users. An interference was observed from the device used to sample the oral fluid, consequently this was excluded from the method which was validated on oral fluid obtained by spitting in a test-tube.
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- 2002
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15. Reference measurement systems in clinical chemistry.
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Thienpont LM, Van Uytfanghe K, and De Leenheer AP
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- Chorionic Gonadotropin analysis, Chorionic Gonadotropin chemistry, Enzymes metabolism, Hemoglobins analysis, Humans, International System of Units, Quality Control, Reference Standards, Triglycerides analysis, Clinical Chemistry Tests methods, Clinical Chemistry Tests standards
- Abstract
Background: In clinical chemistry, traceability of measurements is of high priority., Methods: In this literature review, current recommendations on the process of establishing traceability (or standardization) are critically discussed., Results: Traceability is to be established to the highest international standards by a comprehensive reference measurement system. Elementary to this system are a metrological basis, a measurement unit system, i.e., the Système International d'Unités (SI), its embodiment by a material standard and a calibration hierarchy for transfer of accuracy/trueness to the manufacturer's product calibrators and routine methods. However, for analytes lacking an unequivocally recognized entity, the International Unit (IU) and International Standard (IS) concept have been developed. On this basis, the review distinguishes between traceability of SI- and IU-analytes., Conclusions: SI-traceability, exemplified by cortisol, is straightforward. However, special attention is needed for "free analytes" and "analyte families". For traceability of IU-analytes, exemplified by hCG, the standardization process passes different phases in function of the history of the analyte (discovery, ISs, measurement by bioassays/immunoassays, complete structure elucidation). However, perspectives to the development of an SI-based reference measurement system are realistic. Last but not least, for successful global implementation of the standardization process, consensus of all major players in the field will be required.
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- 2002
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16. Simultaneous determination of in total 17 opium alkaloids and opioids in blood and urine by fast liquid chromatography-diode-array detection-fluorescence detection, after solid-phase extraction.
- Author
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Dams R, Benijts T, Lambert WE, and De Leenheer AP
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- Chromatography, Ion Exchange, Narcotics blood, Narcotics urine, Opium blood, Opium urine, Reference Standards, Reproducibility of Results, Sensitivity and Specificity, Chromatography, High Pressure Liquid methods, Narcotics analysis, Opium analysis, Spectrometry, Fluorescence methods, Spectrophotometry, Ultraviolet methods
- Abstract
A fast liquid chromatographic method with tandem diode array-fluorescence detection for the simultaneous determination of in total 17 opium alkaloids and opioids is presented. Blank blood and urine samples (1 ml) were spiked with different concentrations of a standard mixture, as well as with the internal standard, butorphanol (2000 ng/ml). After solid-phase extraction, based on weak cation exchange (Bond Elut CBA SPE columns), the extracts were examined by HPLC-DAD-FL. By using a "high-speed" phenyl column (53 x 7.0 mm I.D., particle size 3 microm) eluted with a gradient system (A: water-methanol (90:10, v/v), B: methanol, both containing 25 mM triethylammoniumformate (pH(A) = 4.5)) all compounds could be baseline separated within 12 min. The method was validated and its applicability was demonstrated by the analysis of real-time forensic cases.
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- 2002
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17. Distribution study of 3,4-methylenedioxymethamphetamine and 3,4-methylenedioxyamphetamine in a fatal overdose.
- Author
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De Letter EA, Clauwaert KM, Lambert WE, Van Bocxlaer JF, De Leenheer AP, and Piette MH
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- 3,4-Methylenedioxyamphetamine poisoning, Adult, Chromatography, High Pressure Liquid, Fatal Outcome, Humans, Male, N-Methyl-3,4-methylenedioxyamphetamine poisoning, Spectrometry, Mass, Electrospray Ionization, Vitreous Body chemistry, 3,4-Methylenedioxyamphetamine pharmacokinetics, N-Methyl-3,4-methylenedioxyamphetamine pharmacokinetics
- Abstract
In this study, regional tissue distributions of the amphetamine analogue 3,4-methylenedioxymethamphetamine (MDMA, "ecstasy") and its metabolite 3,4-methylenedioxyamphetamine (MDA) in a fatal overdose are presented. Quantitation of MDMA and MDA levels occurred in blood samples taken centrally (right and left heart and main adjacent great vessels) and peripherally (subclavian and femoral blood). In addition, MDMA and MDA concentrations were determined in cardiac and iliopsoas muscle, both lungs, liver, both kidneys, spleen, the four brain lobes, cerebellum and brainstem, and adipose tissue. Finally, MDMA and MDA levels were determined in serum, vitreous humor, urine, and bile. For all samples, a fully validated high-pressure liquid chromatography procedure with fluorescence detection was used. The found substances were also identified with liquid chromatography-tandem mass spectrometry. Our data confirm that blood sampling from an isolated peripheral vein is recommended for MDMA and MDA. In addition, the vitreous humor MDMA level indicates that this fluid can be an interesting alternative when a suitable blood sample is missing. Considering the substantial differences in concentrations in blood samples taken from various sites in the body and the high levels in some tissues (e.g., in liver), we concluded that the influence of postmortem redistribution should be taken into account in the interpretation of toxicological data when an appropriate peripheral sample cannot be obtained or when blood samples are not available because of putrefaction.
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- 2002
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18. Determination of paramethoxyamphetamine and other amphetamine-related designer drugs by liquid chromatography/sonic spray ionization mass spectrometry.
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Mortier KA, Dams R, Lambert WE, De Letter EA, Van Calenbergh S, and De Leenheer AP
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- 3,4-Methylenedioxyamphetamine analysis, Amphetamines, Humans, N-Methyl-3,4-methylenedioxyamphetamine analysis, Reproducibility of Results, 3,4-Methylenedioxyamphetamine analogs & derivatives, Amphetamine analysis, Chromatography, High Pressure Liquid methods, Designer Drugs analysis, Forensic Medicine methods, Spectrometry, Mass, Electrospray Ionization methods
- Abstract
Paramethoxyamphetamine (PMA) is an amphetamine-like designer drug that has emerged recently on the European illicit drug market. This drug has a wicked reputation, as a number of lethal intoxications have occurred. A method using high-performance liquid chromatography coupled to ion trap based mass spectrometry (LC/MS) is described for the determination of this compound together with 3,4-methylenedioxymethamphetamine (XTC or MDMA), amphetamine and 3,4-methylenedioxyamphetamine (MDA) in human matrices. A liquid/liquid extraction (LLE) was applied to whole blood, urine and postmortem tissues. Reversed-phase liquid chromatography was performed on a narrow-bore phenyl-type column at a flow rate of 0.3 mL/min. A switch box allowed disposal of early-eluting irrelevant material to waste, protecting the mass spectrometer from contamination. The column effluent was directed into an ion trap mass spectrometer by a sonic spray ionization (SSI) interface. The method was validated for all three matrices, proving the applicability of SSI even when dealing with complex biological matrices. The within-and between-day precisions were less than 17.5% and accuracy was below 16.2%. Weighted (1/x) quadratic calibration curves were generated ranging from 10 to 1000 ng/mL (blood and urine) or 20 to 2000 ng/g (tissue) and correlation coefficients (r(2)) always exceeded 0.995. In addition, the mass spectrum of PMA is given together with a proposed fragmentation pattern for the obtained LC/MS spectrum. This information can be useful for future identification of PMA with LC/MS in biological matrices as well as in confiscated powders or tablets., (Copyright 2002 John Wiley & Sons, Ltd.)
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- 2002
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19. Quantitative determination of n-propane, iso-butane, and n-butane by headspace GC-MS in intoxications by inhalation of lighter fluid.
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Bouche MP, Lambert WE, Van Bocxlaer JF, Piette MH, and De Leenheer AP
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- Calibration, Gas Chromatography-Mass Spectrometry, Humans, Indicators and Reagents, Reference Standards, Reproducibility of Results, Administration, Inhalation, Butanes blood, Butanes poisoning, Propane blood, Propane poisoning, Substance-Related Disorders blood
- Abstract
This report describes a fully elaborated and validated method for quantitation of the hydrocarbons n-propane, iso-butane, and n-butane in blood samples. The newly developed analytical procedure is suitable for both emergency cases and forensic medicine investigations. Its practical applicability is illustrated with a forensic blood sample after acute inhalative intoxication with lighter fluid; case history and toxicological findings are included. Identification and quantitation of the analytes were performed using static headspace extraction combined with gas chromatography-mass spectrometry. In order to reconcile the large gas volumes injected (0.5 mL) with the narrowbore capillary column and thus achieve preconcentration, cold trapping on a Tenax sorbent followed by flash desorption was applied. Adequate retention and separation were achieved isothermally at 35 degrees C on a thick-film capillary column. Sample preparation was kept to a strict minimum and involved simply adding 2.5 microL of a liquid solution of 1,1,2-trichlorotrifluoroethane in t-butyl-methylether as an internal standard to aliquots of blood in a capped vial. Standards were created by volumetric dilution departing from a gravimetrically prepared calibration gas mixture composed of 0.3% of n-propane, 0.7% of iso-butane, and 0.8% of n-butane in nitrogen. In the forensic blood sample, the following concentrations were measured: 90.0 microg/L for n-propane, 246 microg/L for iso-butane, and 846 microg/L for n-butane.
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- 2002
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20. Simultaneous determination of fifteen low-dosed benzodiazepines in human urine by solid-phase extraction and gas chromatography-mass spectrometry.
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Borrey D, Meyer E, Lambert W, Van Peteghem C, and De Leenheer AP
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- Chromatography, Thin Layer, Humans, Reference Standards, Reproducibility of Results, Sensitivity and Specificity, Benzodiazepines urine, Gas Chromatography-Mass Spectrometry methods
- Abstract
A gas chromatographic-mass spectrometric method was developed for the simultaneous analysis of 15 low-dosed benzodiazepines, both parent compounds and their corresponding metabolites, in human urine. The target compounds are alprazolam, alpha-hydroxyalprazolam, 4-hydroxyalprazolam, flunitrazepam, 7-aminoflunitrazepam, desmethylflunitrazepam, flurazepam, hydroxyethylflurazepam, nitrogen-desalkylflurazepam, ketazolam, oxazepam, lormetazepam, lorazepam, triazolam and alpha-hydroxytriazolam. Nitrogen-methylclonazepam is used as the internal standard. The urine sample preparation involves enzymatic hydrolysis of the conjugated metabolites with Helix pomatia beta-glucuronidase for 1 h at 56 degrees C followed by solid-phase extraction on a phenyl-type column. The extracted benzodiazepines are subsequently analyzed on a polydimethylsiloxane column using on-column injection to enhance sensitivity. The extraction efficiency exceeded 80% for all compounds except for oxazepam, lorazepam and 4-hydroxyalprazolam which had recoveries of about 60%. The LODs ranged from 13 to 30 ng/ml in the scan mode and from 1.0 to 1.7 ng/ml in the selected ion monitoring (SIM) mode. Linear calibration curves were obtained in the concentration ranges from 50 to 1000 ng/ml in the scan mode and from 5 to 100 ng/ml in the SIM mode. The within-day and day-to-day relative standard deviations at three different concentrations never exceeded 15%.
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- 2001
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21. Stability study of the designer drugs "MDA, MDMA and MDEA" in water, serum, whole blood, and urine under various storage temperatures.
- Author
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Clauwaert KM, Van Bocxlaer JF, and De Leenheer AP
- Subjects
- 3,4-Methylenedioxyamphetamine urine, Chromatography, High Pressure Liquid, Drug Storage, N-Methyl-3,4-methylenedioxyamphetamine urine, Reproducibility of Results, Water, 3,4-Methylenedioxyamphetamine analogs & derivatives, 3,4-Methylenedioxyamphetamine blood, Designer Drugs, Drug Stability, Forensic Medicine, N-Methyl-3,4-methylenedioxyamphetamine blood
- Abstract
A controlled study was undertaken to determine the stability of the designer drugs MDA, MDMA and MDEA in pooled serum, whole blood, water and urine samples over a period of 21 weeks. The concentrations of the individual designer drugs in the various matrices were monitored over time, in the dark at various temperatures (-20, 4 or 20 degrees C), for a low (+/- 6 ng/ml for water, serum and whole blood and +/- 150 ng/ml for urine) and a high concentration level (+/- 550 ng/ml for water, serum and whole blood and +/- 2500 ng/ml for urine). Compound concentrations were measured using a validated HPLC assay with fluorescence detection. Our study demonstrated no significant loss of the designer drugs in water and urine at any of the investigated temperatures for 21 weeks. The same results were observed in serum for up to 17 weeks, and up to 5 weeks in whole blood. After that time, the compounds could no longer be analyzed due to matrix degradation, especially in the low concentration samples that were stored at room temperature. This study demonstrates that the designer drugs, MDA, MDMA and MDEA are stable when stored at -20 degrees C for 21 weeks, even in haemolysed whole blood.
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- 2001
- Full Text
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22. Heroin impurity profiling: trends throughout a decade of experimenting.
- Author
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Dams R, Benijts T, Lambert WE, Massart DL, and De Leenheer AP
- Subjects
- Drug Contamination, Chemistry Techniques, Analytical methods, Heroin chemistry, Illicit Drugs chemistry, Narcotics chemistry
- Abstract
Heroin is still one of the most frequently abused drugs of today. All over the world, law enforcement agencies try to eradicate the illicit production and trafficking of this potent and highly addictive narcotic. To this aim, important information is provided by physical and chemical toxicological analysis of confiscated samples, with special attention for the identification and the quantification of minor components, such as the impurities related to the origin and manufacturing. By combining these data complex characterisations, i.e. impurity profiles, chemical signatures or fingerprints, can be obtained and used for comparative analysis. This review focuses on heroin impurity profiling during the 1990s, proclaimed by the United Nations as the 'Decade for Eradicating Drug Abuse'. Special attention will be given to the new trends in analytical techniques as well as in data handling strategies, so called chemometrics, to produce these profiles. The latter can be used in comparative analysis of seized heroin samples for tactical (batch-to-batch comparison) and strategic (origin determination) intelligence purposes.
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- 2001
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23. Only carbon dioxide absorbents free of both NaOH and KOH do not generate compound A during in vitro closed-system sevoflurane: evaluation of five absorbents.
- Author
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Versichelen LF, Bouche MP, Rolly G, Van Bocxlaer JF, Struys MM, De Leenheer AP, and Mortier EP
- Subjects
- Absorption, Humans, Hydroxides, Potassium Compounds, Sevoflurane, Sodium Hydroxide, Temperature, Anesthetics, Inhalation metabolism, Carbon Dioxide metabolism, Ethers metabolism, Hydrocarbons, Fluorinated metabolism, Methyl Ethers metabolism
- Abstract
Background: Insufficient data exist on the production of compound A during closed-system sevoflurane administration with newer carbon dioxide absorbents., Methods: A modified PhysioFlex apparatus (Dräger, Lübeck, Germany) was connected to an artificial test lung (inflow at the top of the bellow approximately/= 160 ml/min CO2; outflow at the Y piece of the lung model approximately/= 200 ml/min, simulating oxygen consumption). Ventilation was set to obtain an end-tidal carbon dioxide partial pressure of approximately 40 mmHg. Various fresh carbon dioxide absorbents were used: Sodasorb (n = 6), Sofnolime (n = 6), and potassium hydroxide (KOH)-free Sodasorb (n = 7), Amsorb (n = 7), and lithium hydroxide (n = 7). After baseline analysis, liquid sevoflurane was injected into the circuit by syringe pump to obtain 2.1% end-tidal concentration for 240 min. At baseline and at regular intervals thereafter, end-tidal carbon dioxide partial pressure, end-tidal sevoflurane concentration, and canister inflow (T degrees(in)) and canister outflow (T degrees(out)) temperatures were measured. To measure compound Ainsp concentration in the inspired gas of the breathing circuit, 2-ml gas samples were taken and analyzed by capillary gas chromatography plus mass spectrometry., Results: The median (minimum-maximum) highest compound Ainsp concentrations over the entire period were, in decreasing order: 38.3 (28.4-44.2)* (Sofnolime), 30.1 (23.9-43.7) (KOH-free Sodasorb), 23.3 (20.0-29.2) (Sodasorb), 1.6 (1.3-2.1)* (lithium hydroxide), and 1.3 (1.1-1.8)* (Amsorb) parts per million (*P < 0.01 vs. Sodasorb). After reaching their peak concentration, a decrease for Sofnolime, KOH-free Sodasorb, and Sodasorb until 240 min was found. The median (minimum-maximum) highest values for T degrees(out) were 39 (38-40), 40 (39-42), 41 (40-42), 46 (44-48)*, and 39 (38-41) degrees C (*P < 0.01 vs. Sodasorb), respectively., Conclusions: With KOH-free (but sodium hydroxide [NaOH]-containing) soda limes even higher compound A concentrations are recorded than with standard Sodasorb. Only by eliminating KOH as well as NaOH from the absorbent (Amsorb and lithium hydroxide) is no compound A produced.
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- 2001
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24. A fatal case of serotonin syndrome after combined moclobemide-citalopram intoxication.
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Dams R, Benijts TH, Lambert WE, Van Bocxlaer JF, Van Varenbergh D, Van Peteghem C, and De Leenheer AP
- Subjects
- Adult, Antidepressive Agents metabolism, Chromatography, High Pressure Liquid, Citalopram metabolism, Drug Combinations, Enzyme Multiplied Immunoassay Technique, Fatal Outcome, Gas Chromatography-Mass Spectrometry, Humans, Male, Moclobemide metabolism, Radioimmunoassay, Serotonin Syndrome pathology, Antidepressive Agents poisoning, Citalopram poisoning, Moclobemide poisoning, Serotonin Syndrome chemically induced, Suicide
- Abstract
We present a case involving a fatality due to the combined ingestion of two different types of antidepressants. A 41-year-old Caucasian male, with a history of depression and suicide attempts, was found deceased at home. Multiple containers of medication, the MAO-inhibitor moclobemide (Aurorix), the SSRI citalopram (Cipramil), and the benzodiazepine lormetazepam (Noctamid) as active substance, as well as a bottle of whiskey were present at the scene. The autopsy findings were unremarkable, but systematic toxicological analysis (EMIT, radioimmunoassay, high-performance liquid chromatography-diode-array detection [HPLC-DAD], gas chromatography-nitrogen-phosphorus detection, and gas chromatography-mass spectrometry) revealed the following: ethanol (0.23 g/L blood, 0.67 g/L urine), lormetazepam (1.65 microg/mL urine), cotinine (0.63 microg/mL blood, 5.08 microg/mL urine), caffeine (1.20 microg/mL urine), moclobemide (and metabolites), and citalopram (and metabolite). There upon, we developed a new liquid chromatographic separation with optimized DAD, preceded by an automated solid-phase extraction, for the quantitation of the previously mentioned antidepressive drugs. The results obtained for blood and urine, respectively, were as follows: Ro 12-5637 (moclobemide N'-oxide) not detected and 424 microg/mL; Ro 12-8095 (3-keto-moclobemide) 2.26 microg/mL and 49.7 microg/mL; moclobemide 5.62 microg/mL and 204 microg/mL; desmethylcitalopram 0.42 microg/mL and 1.22 microg/mL; and citalopram 4.47 microg/mL and 19.7 microg/mL. The cause of death was attributed to the synergistic toxicity of moclobemide and citalopram, both antidepressants, which, by intentional or accidental combined ingestion, can produce a potentially lethal hyperserotoninergic state. Based on the history of the case and pharmacology of the drugs involved, the forensic pathologists ruled that the cause of death was multiple drug intoxication, resulting in a fatal "serotonin syndrome," and that the manner of death was suicide.
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- 2001
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25. Compound A production from sevoflurane is not less when KOH-free absorbent is used in a closed-circuit lung model system.
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Versichelen L, Bouche MP, Struys M, Van Bocxlaer J, Mortier E, de Leenheer AP, and Rolly G
- Subjects
- Absorption, Carbon Dioxide chemistry, Humans, Hydroxides chemistry, Lung, Models, Biological, Potassium Compounds chemistry, Sevoflurane, Anesthesia, Closed-Circuit, Anesthetics, Inhalation chemistry, Calcium Compounds chemistry, Ethers chemistry, Hydrocarbons, Fluorinated chemistry, Methyl Ethers chemistry, Oxides chemistry, Sodium Hydroxide chemistry
- Abstract
In an in vitro study, less compound A was formed when a KOH-free carbon dioxide absorbent was used. To confirm this observation we used a lung model in which carbon dioxide was fed in at 160 ml min(-1) and sampling gas was taken out for analysis at 200 ml min(-1); ventilation aimed for a PE'CO2 of 5.4 kPa. The soda lime canister temperatures in the inflow and outflow ports (Tin and Tout) were recorded. In six runs of 240 min each, a standard soda lime, Sodasorb (Grace, Epernon, France) was used and in eight runs KOH-free Sofnolime (Molecular Products, Thaxted, UK) was used. Liquid sevoflurane was injected using a syringe pump to obtain 2.1% E'. Compound A was measured by capillary gas chromatography combined with mass spectrometry. Median (range) compound Ainsp increased to a maximum of 22.7 (7.9) ppm for Sodasorb and 33.1 (20) for Sofnolime at 60 min and decreased thereafter; the difference between groups was significant (P<0.05) at each time of analysis up to 240 min. The canister temperatures were similar in both groups and increased to approximately 40 degrees C at 240 min. Contrary to expectation, compound A concentrations were greater with the KOH-free absorbent despite similar canister temperatures with both absorbents.
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- 2001
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26. Sensitive gas chromatographic--mass spectrometric screening of acetylated benzodiazepines.
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Borrey D, Meyer E, Lambert W, Van Calenbergh S, Van Peteghem C, and De Leenheer AP
- Subjects
- Acetylation, Reference Standards, Reproducibility of Results, Sensitivity and Specificity, Benzodiazepines chemistry, Gas Chromatography-Mass Spectrometry methods
- Abstract
GC-MS screening conditions were developed for 15 low-dosed benzodiazepines, covering alprazolam, flunitrazepam, flurazepam, ketazolam, lorazepam and triazolam, and the corresponding metabolites alpha-hydroxyalprazolam, 4-hydroxyalprazolam; 7-aminoflunitrazepam, desmethylflunitrazepam, 7-aminodesmethylflunitrazepam; hydroxyethylflurazepam, N-desalkylflurazepam; oxazepam and alpha-hydroxytriazolam, respectively. Benzodiazepines are analyzed on a polydimethylsiloxane column in both the scan and the multiple ion monitoring modes using on-column injection to attain maximal sensitivity. The reactive compounds are acetylated with pyridine and acetic anhydride for 20 min. The derivatives are stable for at least 4 days. The relative standard deviation observed with standard compounds at the low nanogram-level ranged from 1.13 to 4.87% within-day and from 1.12 to 4.94% between-day. Unequivocal identification potential, high chromatographic resolution and sensitivity are combined with minimal thermal degradation. The presented screening conditions provide the basis for a unique routine screening method for low-dosed benzodiazepines with a broad polarity range.
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- 2001
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27. Quantitative determination of vapor-phase compound A in sevoflurane anesthesia using gas chromatography-mass spectrometry.
- Author
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Bouche MP, Van Bocxlaer JF, Rolly G, Versichelen LF, Struys MM, Mortier E, and De Leenheer AP
- Subjects
- Air analysis, Gas Chromatography-Mass Spectrometry, Methyl Ethers toxicity, Reproducibility of Results, Sensitivity and Specificity, Sevoflurane, Volatilization, Anesthetics, Inhalation chemistry, Ethers analysis, Hydrocarbons, Fluorinated analysis, Methyl Ethers chemistry
- Abstract
Background: During low-flow or closed-circuit anesthesia with the fluorinated inhalation anesthetic sevoflurane, compound A, an olefinic degradation product with known nephrotoxicity in rats, is generated on contact with alkaline CO(2) adsorbents. To evaluate compound A formation and thus potential sevoflurane toxicity, a reliable and reproducible assay for quantitative vapor-phase compound A determination was developed., Methods: Compound A concentrations were measured by fully automated capillary gas chromatography-mass spectrometry with cryofocusing. Calibrators of compound A in the vapor phase were prepared from liquid volumetric dilutions of stock solutions of compound A and sevoflurane in ethyl acetate. 1,1,1-Trifluoro-2-iodoethane was chosen as an internal standard. The resulting quantitative method was fully validated., Results: A linear response over a clinically useful concentration interval (0.3-75 microL/L) was obtained. Specificity, sensitivity, and accuracy conformed with current analytical requirements. The CVs were 4.1-10%, the limit of detection was 0.1 microL/L, and the limit of quantification was 0.3 microL/L. Analytical recoveries were 100.6% +/- 10.1%, 102.5% +/- 7.3%, and 99.0% +/- 4.1% at 0.5, 10, and 75 microL/L, respectively. The method described was used to determine compound A concentrations during simulated closed-circuit conditions. Some of the resulting data are included, illustrating the practical applicability of the proposed analytical approach., Conclusions: A simple, fully automated, and reliable quantitative analytical method for determination of compound A in air was developed. A solution was established for sampling, calibration, and chromatographic separation of volatiles in an area complicated by limited availability of sample volume and low concentrations of the analyte.
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- 2001
28. Computer-aided screening for hallucinogenic and stimulant amphetamines with gas chromatography-Fourier transform infrared spectroscopy (GC-FTIR).
- Author
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Praisler M, Dirinck I, Van Bocxlaer JF, De Leenheer AP, and Massart DL
- Subjects
- Chromatography, Gas, Spectroscopy, Fourier Transform Infrared, Amphetamines analysis, Hallucinogens analysis
- Abstract
An expert system applied as a screening test for amphetamine analogues found in recreational-drug exhibits (tablets or powders) is described. The knowledge base defining the reference Fourier transform infrared spectroscopic (FTIR) spectral patterns has been built according to criteria encompassing toxicological, pharmacological, and neurochemical aspects. The class identity of a compound is determined within seconds using soft independent modeling of class analogy (SIMCA). The predictive value of the system, as assessed at a testing accuracy of 95%, is expressed by a total correct classification rate of 93.93% and by a 96.30% rate of true-positive amphetamines. The specificity and the selectivity of the screening test, evaluated by testing 159 toxicologically relevant compounds, are discussed, emphasizing the chemical and physical factors affecting these parameters. Medicinal amphetamines giving cross-reactions with traditional screening techniques produce a negative result. The specificity of the system characterizes the expert system as a highly sensitive, selective, fast, and user-friendly screening test that screens for amphetamines with prediction accuracy adequate for investigations in analytical toxicology.
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- 2001
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29. A convenient method for the generation of negative and positive electrospray ionization mass spectra of proteins by gas-phase admission of volatile bases and acids via the nebulizing gas.
- Author
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Fierens C, Stöckl D, Thienpont LM, and De Leenheer AP
- Subjects
- Acids chemistry, Alkalies chemistry, Nebulizers and Vaporizers, Proteins chemistry, Volatilization, Proteins analysis, Spectrometry, Mass, Electrospray Ionization methods
- Published
- 2001
- Full Text
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30. Pitfalls associated with liquid chromatography/electrospray tandem mass spectrometry in quantitative bioanalysis of drugs of abuse in saliva.
- Author
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Mortier KA, Clauwaert KM, Lambert WE, Van Bocxlaer JF, Van den Eeckhout EG, Van Peteghem CH, and De Leenheer AP
- Subjects
- Chromatography, Liquid, Humans, Spectrometry, Mass, Electrospray Ionization, Saliva chemistry, Substance Abuse Detection methods
- Published
- 2001
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31. Strategies for determination of insulin with tandem electrospray mass spectrometry: implications for other analyte proteins?
- Author
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Fierens C, Stöckl D, Thienpont LM, and De Leenheer AP
- Subjects
- Humans, Hydrogen-Ion Concentration, Indicators and Reagents, Molecular Weight, Sequence Analysis, Protein methods, Spectrometry, Mass, Electrospray Ionization methods, Insulin chemistry, Proteins chemistry
- Abstract
Using human insulin (MW 5808 Da) as a model compound, the possible strategies towards optimization of sensitivity and selectivity of measurement by electrospray ionization with a standard triple quadrupole mass spectrometer were investigated. For measurement in selected ion-monitoring (SIM) mode, these strategies involved systematic variation of instrumental parameters and spray pH. In this investigation four different operating modes were used corresponding to positive/negative ionization modes with acidic/basic sprays and pH reversed (hereafter termed 'wrong-way-round' operation); the cone voltage was optimized for each mode of operation. When collision-activated dissociation (CAD) is employed, two additional operation modes are possible: namely, low collision energies (10-35 eV, CAD-l) for the generation of sequence-specific fragments and high collision energies (>80 eV, CAD-h) for the generation of nonspecific fragments. Overall, this results in twelve different modes of operation. Loop-injection of aqueous insulin standards were run for each of the twelve operating modes and measurements made for five different charge states (n = 2-6) observable with our instrument that has an upper mass limit of m/z 4000. The signal/noise (S/N) ratio was optimized for each charge state, resulting in 60 measurements. The best S/N ratios (20 000) were achieved under positive SIM conditions with charge state 6 (m/z 969) and under 'wrong-way-round' negative SIM conditions with charge state 3 (m/z 1935). Lower S/N ratios were observed under positive CAD-h conditions with charge state 5 (m/z 1163, S/N 15 000) and positive CAD-l conditions with charge state 6 (m/z 969, S/N 10 000). All other operating modes gave maximum S/N ratios of 4000. For measurement of insulin standards, the results obtained show SIM to give the best S/N ratio. However, for samples in complex matrices, our general experience suggests CAD to be the preferable operating mode. Consequently, for the development of a quantitative method for proteins in general, it might be advocated that all of the twelve operating modes and all relevant charge states be investigated to find the optimum S/N ratio., (Copyright 2001 John Wiley & Sons, Ltd.)
- Published
- 2001
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32. Determination of the designer drugs 3, 4-methylenedioxymethamphetamine, 3,4-methylenedioxyethylamphetamine, and 3,4-methylenedioxyamphetamine with HPLC and fluorescence detection in whole blood, serum, vitreous humor, and urine.
- Author
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Clauwaert KM, Van Bocxlaer JF, De Letter EA, Van Calenbergh S, Lambert WE, and De Leenheer AP
- Subjects
- 3,4-Methylenedioxyamphetamine blood, 3,4-Methylenedioxyamphetamine urine, Animals, Chromatography, High Pressure Liquid, Humans, Mass Spectrometry, N-Methyl-3,4-methylenedioxyamphetamine blood, N-Methyl-3,4-methylenedioxyamphetamine urine, Rabbits, Reproducibility of Results, Sensitivity and Specificity, Spectrometry, Fluorescence, 3,4-Methylenedioxyamphetamine analogs & derivatives, 3,4-Methylenedioxyamphetamine analysis, Designer Drugs analysis, N-Methyl-3,4-methylenedioxyamphetamine analysis, Substance Abuse Detection methods, Vitreous Body chemistry
- Abstract
Background: The popular designer drugs 3, 4-methylenedioxymethamphetamine (MDMA) and 3, 4-methylenedioxyethylamphetamine (MDEA) can be determined in serum, whole blood, and urine, but also in vitreous humor. The latter matrix is interesting when dealing with decomposed bodies in a toxicological setting., Methods: After extraction, chromatographic separation was achieved on a narrow-bore C(18) column by gradient elution with fluorometric detection; results were confirmed by liquid chromatography-tandem mass spectrometry (LC-MS/MS)., Results: The method was linear over the range of 2-1000 microg/L for whole blood, serum, and vitreous humor, and 0.1-5 mg/L for urine. Extraction recoveries were >70%, imprecision (CV) was 2.5-19%, and analytical recoveries were 95.5-104.4%. The limit of detection (LOD) and the limit of quantification (LOQ) were 0.8 and 2 microg/L, respectively, for whole blood, serum, and vitreous humor, and 2.5 microg/L and 0.1 mg/L, respectively, for urine. Excellent correlations between the quantitative LC-fluorescence and LC-MS/MS results were obtained. We found the following concentrations in a thanatochemical distribution study in rabbits: in serum, 5.3-685 microg/L for MDMA and from the LOQ to 14.5 microg/L for 3, 4-methylenedioxyamphetamine (MDA); in whole blood, 19.7-710 microg/L for MDMA and from the LOQ to 17.8 microg/L for MDA; in vitreous humor, 12.1-97.8 microg/L for MDMA and from the LOQ to 3.86 microg/L for MDA. In routine toxicological urine samples, concentrations ranged from LOQ to 14.62 mg/L for MDA, from LOQ to 157 mg/L for MDMA, and from LOQ to 32.54 mg/L for MDEA., Conclusions: The HPLC method described is sensitive, specific, and suitable for the determination of MDMA, MDEA, and MDA in whole blood, serum, vitreous humor, and urine.
- Published
- 2000
33. Comparison of phenyl-type columns in the development of a fast liquid chromatographic system for eighteen opiates commonly found in forensic toxicology.
- Author
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Dams R, Lambert WE, Clauwaert KM, and De Leenheer AP
- Subjects
- Buffers, Cations, Narcotics toxicity, Reference Standards, Sensitivity and Specificity, Spectrophotometry, Ultraviolet, Chromatography, High Pressure Liquid methods, Forensic Medicine, Narcotics analysis
- Abstract
We report a precise and reliable method for the detection of 18 of the most commonly found opiates on the Belgian legal and illicit market, by ion-exchange, reversed-phase high-performance liquid chromatography, using a conventional phenyl-type analytical column (150x4.6 mm I.D., particle size 5 microm) and diode-array detection. We also describe a performance (efficiency and sensitivity) comparison of this column to a recently developed "high-speed" column (53x7.0 mm I.D., particle size 3 microm) packed with the same stationary phase, and used under slightly adjusted flow and gradient conditions. The final method, using the "high-speed" column, showed a significant reduction (55%) in analysis time without loss of resolution and sensitivity.
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- 2000
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34. Quantitative analysis of urinary C-peptide by liquid chromatography-tandem mass spectrometry with a stable isotopically labelled internal standard.
- Author
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Fierens C, Thienpont LM, Stöckl D, Willekens E, and De Leenheer AP
- Subjects
- Calibration, Deuterium, Humans, Reference Standards, Reproducibility of Results, Sensitivity and Specificity, Chromatography, Liquid methods, Mass Spectrometry methods
- Abstract
We describe the first results of a quantitative LC-tandem mass spectrometry method for urinary C-peptide with the use of [2H14]C-peptide as internal standard. LC was based on gradient elution of a Hypersil PEP C18 column. Mass spectrometry was performed in the negative electrospray ionization mode and by monitoring of the transitions at m/z 1514/1334 ([2H14]C-peptide) and 1507/1320 (C-peptide). For sample preparation, we applied ultrafiltration. The analytical performance of the method in terms of measurement precision gave an RSD of <2% (n=10). The overall imprecision was investigated from independent analysis of two urine samples in six-fold and resulted in an RSD<5%. The limit of detection, expressed as signal-to-noise ratio 3, was approximately 0.15 ng C-peptide injected. Analysis of 10 random urine samples from laboratory volunteers showed interference-free ion chromatograms at a signal-to-noise ratio of approximately 75 on average. The C-peptide concentrations calculated from quantification by the bracketing calibration technique ranged from 32 to 165 ng/ml.
- Published
- 2000
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35. In vitro compound A formation in a computer-controlled closed-circuit anesthetic apparatus. Comparison with a classical valve circuit.
- Author
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Versichelen LF, Rolly G, Bouche MP, Van Bocxlaer JF, Struys MM, Van Der Herten C, De Leenheer AP, and Mortier EP
- Subjects
- Anesthetics, Inhalation administration & dosage, Carbon Dioxide metabolism, Computers, Drug Stability, Ethers administration & dosage, Humans, Hydrocarbons, Fluorinated administration & dosage, Methyl Ethers administration & dosage, Models, Biological, Partial Pressure, Positive-Pressure Respiration, Sevoflurane, Ventilators, Mechanical, Anesthesia, Closed-Circuit instrumentation, Anesthesia, Closed-Circuit methods, Anesthetics, Inhalation pharmacokinetics, Ethers pharmacokinetics, Hydrocarbons, Fluorinated pharmacokinetics, Methyl Ethers pharmacokinetics
- Abstract
Background: Few data exist on compound A during sevoflurane anesthesia when using closed-circuit conditions and sodalime with modern computer-controlled liquid injection., Methods: A PhysioFlex apparatus (Dräger, Lübeck, Germany) was connected to an artificial test lung (inflow approximately 160 ml/min carbon dioxide, outflow approximately 200 ml/min, simulating oxygen consumption). Ventilation was set to obtain an end-tidal carbon dioxide partial pressure (Petco2) approximately 40 mmHg. Canister inflow (T degrees in) and outflow (T degrees out) temperatures were measured. Fresh sodalime and charcoal were used. After baseline analysis, sevoflurane concentration was set at 2.1% end-tidal for 120 min. At baseline and at regular intervals thereafter, Petco2, end-tidal sevoflurane, T degrees in, and T degrees out were measured. For inspiratory and expiratory compound A determination, samples of 2-ml gas were taken. These data were compared with those of a classical valve-containing closed-circuit machine. Ten runs were performed in each set-up., Results: Inspired compound A concentrations increased from undetectable to peak at 6.0 (SD 1.3) and 14.3 (SD 2.5) ppm (P < 0.05), and maximal temperature in the upper outflow part of the absorbent canister was 24.3 degrees C (SD 3.6) and 39.8 degrees C (SD 1.2) (P < 0.05) in the PhysioFlex and valve circuit machines, respectively. Differences between the two machines in compound A concentrations and absorbent canister temperature at the inflow and outflow regions were significantly different (P < 0.05) at all times after 5 min., Conclusion: Compound A concentrations in the high-flow (70 l/min), closed-circuit PhysioFlex machine were significantly lower than in conventional, valve-based machines during closed-circuit conditions. Lower absorbent temperatures, resulting from the high flow, appear to account for the lower compound A formation.
- Published
- 2000
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36. Overcoming practical limitations for the application of ultrafiltration in sample preparation for liquid chromatography/ mass spectrometry of small proteins.
- Author
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Fierens C, Thienpont LM, Stöckl D, and De Leenheer AP
- Subjects
- Amino Acid Sequence, Molecular Sequence Data, Molecular Weight, C-Peptide chemistry, Chromatography, Liquid methods, Mass Spectrometry methods, Ultrafiltration methods
- Published
- 2000
- Full Text
- View/download PDF
37. Medico-legal implications of hidden thyroid dysfunction: a study of two cases.
- Author
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De Letter EA, Piette MH, Lambert WE, and De Leenheer AP
- Subjects
- Adult, Female, Humans, Hyperthyroidism pathology, Male, Middle Aged, Autopsy methods, Death, Sudden etiology, Graves Disease pathology, Hypothyroidism pathology, Thyroiditis, Autoimmune pathology
- Abstract
In this paper we present two cases in which thyroid disorders were unexpectedly brought to view. The question we ponder is whether hidden thyroid dysfunction may be important in the cause, mechanism and manner of death, or just an incidental discovery during the post-mortem examination. A short literature review has been conducted in order to evaluate previously reported cases of thyroid pathology and sudden death. The significance of post-mortem evaluation of thyroid hormones (T3 and T4) will be considered briefly.
- Published
- 2000
- Full Text
- View/download PDF
38. Liquid chromatography-mass spectrometry in forensic toxicology.
- Author
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Van Bocxlaer JF, Clauwaert KM, Lambert WE, Deforce DL, Van den Eeckhout EG, and De Leenheer AP
- Subjects
- Chromatography, Liquid, Humans, Mass Spectrometry, Substance Abuse Detection instrumentation, Forensic Medicine instrumentation, Toxicology instrumentation
- Abstract
Liquid chromatography-mass spectrometry has evolved from a topic of mainly research interest into a routinely usable tool in various application fields. With the advent of new ionization approaches, especially atmospheric pressure, the technique has established itself firmly in many areas of research. Although many applications prove that LC-MS is a valuable complementary analytical tool to GC-MS and has the potential to largely extend the application field of mass spectrometry to hitherto "MS-phobic" molecules, we must recognize that the use of LC-MS in forensic toxicology remains relatively rare. This rarity is all the more surprising because forensic toxicologists find themselves often confronted with the daunting task of actually searching for evidence materials on a scientific basis without any indication of the direction in which to search. Through the years, mass spectrometry, mainly in the GC-MS form, has gained a leading role in the way such quandaries are tackled. The advent of robust, bioanalytically compatible combinations of liquid chromatographic separation with mass spectrometric detection really opens new perspectives in terms of mass spectrometric identification of difficult molecules (e.g., polar metabolites) or biopolymers with toxicological relevance, high throughput, and versatility. Of course, analytical toxicologists are generally mass spectrometry users rather than mass spectrometrists, and this difference certainly explains the slow start of LC-MS in this field. Nevertheless, some valuable applications have been published, and it seems that the introduction of the more universal atmospheric pressure ionization interfaces really has boosted interests. This review presents an overview of what has been realized in forensic toxicological LC-MS. After a short introduction into LC-MS interfacing operational characteristics (or limitations), it covers applications that range from illicit drugs to often abused prescription medicines and some natural poisons. As such, we hope it can act as an appetizer to those involved in forensic toxicology but still hesitating to invest in LC-MS.
- Published
- 2000
- Full Text
- View/download PDF
39. Segmental analysis for cocaine and metabolites by HPLC in hair of suspected drug overdose cases.
- Author
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Clauwaert KM, Van Bocxlaer JF, Lambert WE, and De Leenheer AP
- Subjects
- Cocaine analogs & derivatives, Cocaine-Related Disorders diagnosis, Drug Overdose, Forensic Medicine, Humans, Chromatography, High Pressure Liquid, Cocaine analysis, Cocaine poisoning, Hair chemistry
- Abstract
Hair samples of eight postmortem cases were analyzed in segments of 1 to 3 cm for cocaine, benzoylecgonine and cocaethylene. Samples were prepared for analysis by digestion in 0.1 M HCl and subsequent extraction with mixed-mode solid-phase extraction columns. Measurement was made by reversed-phase, narrow-bore HPLC and fluorescence detection using two laboratory-made internal standards. The concentrations were in the region of 0.29-316 ng/mg of hair for cocaine, 0.43-141 ng/mg of hair for benzoylecgonine and 0.93-1.83 ng/mg of hair for cocaethylene. All eight investigated cases had cocaine-positive segments. In six of the cases, all segments were positive, suggesting regular cocaine use and two showed in-between negative segments indicating an interruption or a change of the abuse intensity. The results showed a second, remarkable observation, i.e. enormous concentration differences (factor >150) for both cocaine and benzoylecgonine between the different subjects. Furthermore, interindividual cocaine/benzoylecgonine ratios ranged from 0.02 to 8.43. We believe these observations could in part be attributed to both some of the still existing limitations in the analytical approach(es), especially the mandatory hair washing steps, and in our still too limited knowledge of the hair incorporation processes. Nevertheless, in some cases, segmental analysis proved to be an important tool to distinguish, together with postmortem examination, deadly chronic abuse from single acute drug overdosage.
- Published
- 2000
- Full Text
- View/download PDF
40. Quantification of glycohemoglobin in blood by mass spectrometry applying multiple-reaction monitoring.
- Author
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Willekens E, Thienpont LM, Stöckl D, Kobold U, Hoelzel W, and De Leenheer AP
- Subjects
- Chromatography, High Pressure Liquid, Humans, Mass Spectrometry, Glycated Hemoglobin analysis
- Published
- 2000
41. Matrix effect in the quantitative analysis of urinary C-peptide by liquid chromatography/mass spectrometry.
- Author
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Fierens C, Thienpont LM, Stöckl D, and De Leenheer AP
- Subjects
- Chromatography, Liquid methods, Humans, Ions, Solutions, Water, C-Peptide urine, Mass Spectrometry methods
- Published
- 2000
- Full Text
- View/download PDF
42. Evaluation of automated single mass spectrometry to tandem mass spectrometry function switching for comprehensive drug profiling analysis using a quadrupole time-of-flight mass spectrometer.
- Author
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Decaestecker TN, Clauwaert KM, Van Bocxlaer JF, Lambert WE, Van den Eeckhout EG, Van Peteghem CH, and De Leenheer AP
- Subjects
- Autoanalysis, Calibration, Chromatography, High Pressure Liquid, Evaluation Studies as Topic, Forensic Medicine methods, Haloperidol analysis, Humans, Indicators and Reagents, Mass Spectrometry, Nalorphine analysis, Urinalysis, Pharmaceutical Preparations analysis, Substance Abuse Detection methods
- Abstract
A liquid chromatographic mass spectrometric strategy for systematic toxicological analysis (STA) is presented using the automatic 'on-the-fly' single mass spectrometry mode to tandem mass spectrometry mode (MS to MS/MS) switching abilities of a quadrupole time-of-flight (Q-TOF) instrument. During the chromatographic run, the quadrupole is initially set to transmit all masses until (an) ion(s) reaches a certain set threshold. Thereupon, the quadrupole automatically switches to the MS/MS mode, selecting the ion(s), which are subsequently fragmented in the high-efficiency hexapole collision cell, thus generating product ions that are further mass analyzed by the TOF. By limiting the TOF spectral accumulation time in the MS/MS mode to a statistically acceptable minimum, the quadrupole almost instantly switches back to the MS mode. Qualitative information, comprising the complementary MS ([M + H](+) ion mass) and MS/MS (informative product ion profile) data, as well as quantitative information obtained by integration of the MS extracted ion chromatogram(s), can be obtained in one single acquisition. Optimization of the automatic switching parameters, such as threshold, TOF spectral accumulation time, detection window and collision energy, was carried out by injection of a mix of 17 common drugs which were not necessarily baseline separated in the chromatographic system used. Indeed, the complete separation of the drugs is not deemed necessary since up to 8 different ions can 'simultaneously' be selected for MS/MS if they reach the preset criteria. In addition, the quantitative performance of the method was defined. In a second phase, the developed method was field-tested. To that end, the resulting data from extracts of urine samples were compared with and found to be in close concordance with those obtained by a standard toxicological analysis. This innovative approach clearly holds the potential for a substantial advance in the introduction of LC/MS in STA., (Copyright 2000 John Wiley & Sons, Ltd.)
- Published
- 2000
- Full Text
- View/download PDF
43. Identification and quantitation of despropionyl-bezitramide in postmortem samples by liquid chromatography coupled to electrospray ionization tandem mass spectrometry.
- Author
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De Baere SM, Lambert WE, Esmans EL, and De Leenheer AP
- Subjects
- Body Fluids chemistry, Humans, Postmortem Changes, Reproducibility of Results, Sensitivity and Specificity, Benzimidazoles analysis, Chromatography, High Pressure Liquid methods, Mass Spectrometry methods
- Abstract
A sensitive and specific method for the determination and quantitation of (despropionyl) bezitramide in postmortem samples using liquid chromatography combined with electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) is presented. The method is the result from a simple methodological transfer of a liquid chromatographic method with fluorescence detection (LC-FL) previously developed in our laboratory. A liquid-liquid back-extraction procedure using n-hexane isoamyl alcohol (93:7, v/v) as the extraction solvent is performed for a basic sample cleanup. N-Methyldespropionyl bezitramide is used as the internal standard. Chromatographic separation of the analytes of interest is achieved on a Hypersil ODS 5-micron column, using a 80:20 (v/v) mixture of 1.0 mM ammonium acetate and methanol/acetonitrile (50:50, v/v) and 1.0 mM ammonium acetate as the mobile phase. To obtain as high a sensitivity and selectivity as possible, a selected reaction-monitoring mass spectrometric technique is applied. In addition, low-energy collisional-activated dissociation (CAD) product ion spectra are recorded for a few samples. Calibration graphs are prepared for blood and urine, and good linearity is achieved over a concentration range of 1-150 ng/mL. The intra- and interassay coefficients of variation (CV%) for the analysis of quality control samples at 10 and 50 ng/mL concentration levels do not exceed 10.2% and percent of targets are within 12.1%. Postmortem samples (blood, urine, stomach contents, bile, liver, and kidney) from three fatalities, all suspected victims of drug overdoses, are analyzed, and the results are reported. The results obtained with LC-ESI-MS/MS are in close agreement with those obtained using the LC-FL method. Moreover, the isolates' identity and structure are confirmed by the CAD product ion spectra, thus allowing to make unequivocal conclusions about the prior intake of bezitramide by the three subjects.
- Published
- 1999
- Full Text
- View/download PDF
44. Simultaneous determination of alpha-tocopheryl acetate and tocopherols in aquatic organisms and fish feed.
- Author
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Huo JZ, Nelis HJ, Lavens P, Sorgeloos P, and De Leenheer AP
- Subjects
- Animals, Aquaculture, Chromatography, High Pressure Liquid, Fishes, Reference Standards, Reproducibility of Results, Spectrophotometry, Ultraviolet, Tocopherols, Animal Feed analysis, Crustacea chemistry, Vitamin E analogs & derivatives, Vitamin E analysis, alpha-Tocopherol analogs & derivatives
- Abstract
In aquaculture, alpha-tocopheryl acetate (alpha-TA) is the main source of vitamin E used to fortify fish feed. alpha-TA in fish is often determined indirectly, i.e., by alkaline hydrolysis, followed by quantitation of "total alpha-tocopherol" (alpha-T) and subtraction of the natively present alpha-T. The aim of this study was to develop an HPLC method for the simultaneous quantitative determination of alpha-TA and free tocopherols in aquatic organisms and fish feed. The assay consists of a simple extraction with methanol containing butylhydroxytoluene (BHT) as an antioxidant, followed by reversed-phase chromatography with consecutive UV and fluorescence detection of alpha-TA and tocopherols, respectively. The peak of the internal standard tocol in the fluorescence trace was used for quantitation. Linearity was achieved over the range of 0.2 to 4.2 micrograms alpha-TA per ml extract of Artemia nauplii, which would correspond to 30.7 to 614.4 micrograms/g dry mass. The within-run coefficient of variation was 1.9% at a level of 310 micrograms/g dry mass. The recovery of alpha-TA ranged from 97.7 to 100.8% (concentration = 2.1 and 20.5 micrograms/ml, n = 6). The detection limit was about 7 ng and the quantification limit on spiked samples was 0.2 microgram/ml. This method was routinely applied to determine alpha-TA and alpha-, gamma- and delta-tocopherol (alpha-T, gamma-T, delta-T) simultaneously in Artemia, fish feed, shrimp eggs and various other aquatic organisms.
- Published
- 1999
- Full Text
- View/download PDF
45. Isotope dilution-gas chromatography/mass spectrometry and liquid chromatography/electrospray ionization-tandem mass spectrometry for the determination of triiodo-L-thyronine in serum.
- Author
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Thienpont LM, Fierens C, De Leenheer AP, and Przywara L
- Subjects
- Carbon Isotopes, Chromatography, High Pressure Liquid, Humans, Quality Control, Sensitivity and Specificity, Thyroxine blood, Triiodothyronine, Reverse blood, Chromatography, Liquid methods, Gas Chromatography-Mass Spectrometry methods, Indicator Dilution Techniques, Mass Spectrometry methods, Triiodothyronine blood
- Abstract
Isotope dilution-gas chromatography/mass spectrometry (ID-GC/MS) and isotope dilution-liquid chromatography/tandem mass spectrometry (ID-LC/MS/MS) methods have been developed for an determination of triiodothyronine (T3) in serum and their potential as candidate reference methods investigated. In both methods, (13)C(9)-T3 was used as internal standard. Sample pretreatment consisted of deproteinization, extraction and high performance liquid chromatography (HPLC) purification. Conversion of serum thyroxine (T4) to T3 was controlled by adding (13)C(6)-T4. For GC/MS, T3 and (13)C(9)-T3 were converted to the N,O-di-heptafluorobutyryl (HFB) methyl ester derivatives and monitored at m/z 844 and 853. For LC/MS with electrospray ionization, the transitions m/z 652/661 to 606/614 were monitored. For use of the methods as candidate reference methods, special attention was paid to the calibration and the measurement protocol (duplicate analysis of each sample on three occasions). Evaluation of the ID-GC/MS and ID-LC/MS/MS methods showed the absence of interference by reverse T3 and T4, a limit of detection of 100 pg (GC/MS) and 18 pg (LC/MS), a recovery of 100 +/- 1.5% (95% confidence interval) and good precision (the total coefficient of variation, n = 6, was typically 1.5%). In addition to the recovery study, the accuracy of the methods was proven by method comparison (ID-GC/MS vs. LC/MS/MS) on three sera, showing a maximum deviation of 1.1%. Finally, the ID-GC/MS method was applied for measurement of 10 different human sera with a T3 concentration range from 0.6 to 7.3 ng/mL., (Copyright 1999 John Wiley & Sons, Ltd.)
- Published
- 1999
- Full Text
- View/download PDF
46. On the use of trimethylchlorosilane in methanol for methylation of thyroxine prior to perfluoroacylation and isotope dilution-gas chromatography/mass spectrometry.
- Author
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De Brabandere VI, Stöckl D, Thienpont LM, and De Leenheer AP
- Subjects
- Acylation, Fluoroacetates chemistry, Gas Chromatography-Mass Spectrometry, Indicators and Reagents, Methylation, Solvents, Methanol chemistry, Thyroxine chemistry, Trimethylsilyl Compounds chemistry
- Published
- 1998
- Full Text
- View/download PDF
47. Narrow-bore HPLC in combination with fluorescence and electrospray mass spectrometric detection for the analysis of cocaine and metabolites in human hair.
- Author
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Clauwaert KM, Van Bocxlaer JF, Lambert WE, Van den Eeckhout EG, Lemière F, Esmans EL, and De Leenheer AP
- Subjects
- Cocaine analogs & derivatives, Cocaine metabolism, Hair metabolism, Humans, Mass Spectrometry, Reproducibility of Results, Spectrometry, Fluorescence, Substance-Related Disorders diagnosis, Chromatography, High Pressure Liquid methods, Cocaine analysis, Hair chemistry
- Abstract
A simple, but sensitive and specific, high-performance liquid chromatographic assay for cocaine, cocaethylene, and benzoylecgonine is described. Using direct fluorometric detection, the procedure is particularly interesting for the routine analysis of human hair samples. In the sample preparation part, the hair samples are cut and washed and two internal standards with close structural resemblance to benzoylecgonine and cocaine as well as to cocaethylene are added. Subsequently, the hair samples are homogenized, hydrolyzed overnight in a 0.1 M HCl solution at 56 degrees C, and extracted on IST Confirm HCX solid-phase extraction columns. Chromatographic separation is achieved on a narrow-bore Hypersil BDS C18 column (125 x 2.1 mm, 3 microns) by gradient elution with an ammonium acetate buffer-methanol/acetonitrile mixture. For the fluorometric detection, excitation and emission wavelengths of 242 and 315 nm, respectively, are used. This analysis protocol affords a method of high sensitivity and specificity which has been fully evaluated and validated. The data presented show good accuracy and linearity with excellent reproducibility and recovery. Because unequivocal identity confirmation is mandatory in forensic applications, an extension of the analysis protocol was accomplished toward mass spectrometric detection. We succeeded in a simple methodological transfer from LC/FL to LC/ESI-MS/MS, thus providing two complementary approaches after a single, common sample-processing step. Hair samples from 29 fatalities, all known drug users and suspected victims from a drug overdose, were analyzed in this way. Of the investigated samples, 12 were positive and the concentrations found range from 0.98 to 938 ng/mg of hair for cocaine and from 1.45 to 388 ng/mg of hair for benzoylecgonine. Traces of cocaethylene were also found in two of the hair samples. The results obtained with LC/ESI-MS/MS were in close agreement with those obtained with LC/FL, positively confirming the isolates' identity and structure by means of the resulting MS/MS spectra.
- Published
- 1998
- Full Text
- View/download PDF
48. Efforts by industry toward standardization of serum estradiol-17 beta measurements.
- Author
-
Thienpont LM and De Leenheer AP
- Subjects
- Blood Specimen Collection methods, Female, Gas Chromatography-Mass Spectrometry instrumentation, Gas Chromatography-Mass Spectrometry methods, Humans, Male, Menstrual Cycle blood, Ovulation Induction, Postmenopause blood, Reference Standards, Regression Analysis, Reproducibility of Results, Estradiol blood
- Published
- 1998
49. Isotope dilution-liquid chromatography/electrospray ionization-tandem mass spectrometry for the determination of serum thyroxine as a potential reference method.
- Author
-
De Brabandere VI, Hou P, Stöckl D, Thienpont LM, and De Leenheer AP
- Subjects
- Calibration, Chromatography, High Pressure Liquid, Gas Chromatography-Mass Spectrometry, Humans, Mass Spectrometry, Reference Values, Reproducibility of Results, Solutions, Thyroxine blood
- Abstract
A new candidate reference method is presented for the determination of thyroxine in serum. The method is based on isotope dilution-liquid chromatography/tandem mass spectrometry using electrospray for ionization. The internal standard used was 13C6-thyroxine, sample pretreatment consisted of protein precipitation and a two-step liquid/liquid extraction procedure, HPLC was performed on a C-18 column with an eluent containing methanol/water/formic acid (60:40:0.1, by volume), and finally thyroxine and its isotopically labeled analogue were measured in the selected reaction monitoring mode for the transitions m/z 777.7--> 731.7 and m/z 783.7--> 737.7, respectively. The detection limit for thyroxine was 6 pg, the within-run coefficient of variation was 1.1%. The samples were measured in six-fold: in duplicate on three independent days. The mean overall coefficient of variation of the method was 1.6%. The new method was evaluated by measuring nine control sera previously determined by an existing ID-GC/MS method. The differences between the results of the two methods ranged from-1.6% to +3.3%, with a mean of +0.2%.
- Published
- 1998
- Full Text
- View/download PDF
50. Quantitative gas chromatographic analysis of [1-(4-piperidinyl)-1,3-dihydro-2H-benzimidazole-2-one], the basic metabolite of bezitramide (Burgodin), in human urine.
- Author
-
De Baere SM, Lambert WE, and De Leenheer AP
- Subjects
- 2-Propanol chemistry, Adult, Benzimidazoles isolation & purification, Benzoates chemistry, Calibration, Chloroform chemistry, Female, Gas Chromatography-Mass Spectrometry, Humans, Magnetic Resonance Spectroscopy, Male, Reference Standards, Reproducibility of Results, Spectrophotometry, Ultraviolet, Spectroscopy, Fourier Transform Infrared, Substance-Related Disorders diagnosis, Analgesics urine, Benzimidazoles urine
- Abstract
A gas chromatographic procedure with nitrogen-phosphorus detection was developed for the quantitative determination of 1-(4-piperidinyl)-1,3-dihydro-2H-benzimidazole-2-one, the basic metabolite of the narcotic analgesic bezitramide (Burgodin), in urine. Gas chromatography with mass spectrometric detection was used for confirmation. An internal standard with great structural resemblance to the basic metabolite was synthesized in our laboratory. For the isolation of the compound from urine, a liquid-liquid extraction with chloroform/isopropanol was performed. The extract was derivatized with pentafluorobenzoylchloride immediately before chromatographic analysis. The calibration curve was linear over a broad concentration range (10 to 1000 ng/mL). The quantitation limit was 10 ng/mL, and at a 250-ng/mL concentration, coefficients of variation of 2.8 and 3.4% were obtained for within-day and between-day precision, respectively. The selectivity and accuracy of the method were satisfactory. Out of 150 urine samples, mainly from persons suspected of using bezitramide or from known drug abusers, 22 samples revealed basic metabolite concentrations that ranged from 17.0 to 1695.5 ng/mL. The described method allows the quantitation of the basic metabolite of bezitramide with high sensitivity, selectivity, and precision. It can also be used to determine bezitramide abuse and to establish bezitramide overdoses.
- Published
- 1998
- Full Text
- View/download PDF
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