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High-resolution mass spectrometry (HRMS) data has revolutionized the identification of environmental contaminants through non-targeted analysis (NTA). However, chemical identification remains challenging due to the vast number of unknown molecular features typically observed in environmental samples. Advanced data processing techniques are required to improve chemical identification workflows. The ideal workflow brings together a variety of data and tools to increase the certainty of identification. One such tool is chromatographic retention time (RT) prediction, which can be used to reduce the number of possible suspect chemicals within an observed RT window. This paper compares the relative predictive ability and applicability to NTA workflows of three RT prediction models: (1) a logP (octanol-water partition coefficient)-based model using EPI Suite™ logP predictions; (2) a commercially available ACD/ChromGenius model; and, (3) a newly developed Quantitative Structure Retention Relationship model called OPERA-RT. Models were developed using the same training set of 78 compounds with experimental RT data and evaluated for external predictivity on an identical test set of 19 compounds. Both the ACD/ChromGenius and OPERA-RT models outperformed the EPI Suite™ logP-based RT model ( R 2 = 0.81–0.92, 0.86-0.83, 0.66–0.69 for training-test sets, respectively). Further, both OPERA-RT and ACD/ChromGenius predicted 95% of RTs within a ± 15% chromatographic time window of experimental RTs. Based on these results, we simulated an NTA workflow with a ten-fold larger list of candidate structures generated for formulae of the known test set chemicals using the U.S. EPA's CompTox Chemistry Dashboard ( https://comptox.epa.gov/dashboard ), RTs for all candidates were predicted using both ACD/ChromGenius and OPERA-RT, and RT screening windows were assessed for their ability to filter out unlikely candidate chemicals and enhance potential identification. Compared to ACD/ChromGenius, OPERA-RT screened out a greater percentage of candidate structures within a 3-min RT window (60% vs. 40%) but retained fewer of the known chemicals (42% vs. 83%). By several metrics, the OPERA-RT model, generated as a proof-of-concept using a limited set of open source data, performed as well as the commercial tool ACD/ChromGenius when constrained to the same small training and test sets. As the availability of RT data increases, we expect the OPERA-RT model's predictive ability will increase. [ABSTRACT FROM AUTHOR]

A sensitive and background-free pre-column derivatization method for the determination of thiol compounds using metal-organic framework material (MOF-5) as dispersive solid-phase extraction (DSPE) adsorbent followed by high-performance liquid chromatography fluorescence detection (HPLC-FLD) has been developed. In this paper, a novel labeling reagent, carbazole-9-ethyl-2-maleimide(CAEM), was synthesized and reacted with thiols at 40 °C for 10 min in the presence of PBS buffer (0.02 mol/L, pH 7.5). Interestingly, CAEM itself had no fluorescence, while its derivatives exhibited intense fluorescence with an excitation maximum at λ ex 274 nm and an emission maximum at λ em 363 nm, which greatly reduced the background interference and improved the sensitivity of the method. Furthermore, the MOF-5 was prepared and used as DSPE adsorbent for the selective adsorption of thiols from wastewater sample. Under the optimized experimental conditions, an excellent linearity for all analytes over their concentration ranges of 0.01–1.0 μmol/L (R 2 >0.9986)were obtained with the limit of detection (LOD) ranging from 8 to 17.1 pmol/L for nine tested thiols. The feasibility of this method for the determination of thiols in wastewater samples had been evaluated and satisfactory average recoveries ( n =3) were achieved with the range of 86.6–98.5%. [ABSTRACT FROM AUTHOR]

A stable zirconium (Ⅳ)-based metal organic frameworks (UIO-67) material possessing good chemical, thermal and water stability was synthesized and applied as a sorbent for the dispersive solid phase extraction (DSPE) of 8 plant growth regulators (PGRs) in fruit samples. Fluorescence labeling combined with high performance liquid chromatography fluorescence detection (HPLC-FLD), was used to quantify the target analytes. Characterization of the UIO-67 material was performed by X-ray diffraction(XRD) and scanning electron microscopy (SEM). The experimental parameters, such as amount of UIO-67, type and volume of eluting solvent, adsorption and desorption time, were optimized. Under the optimized conditions, good linearity was observed in the range of 10–1000 pmol/mL with R 2 >0.9989. The limits of detection and limits of quantification were in the range of 0.21–0.57 ng/mL and 0.81–1.91 ng/mL, respectively. The intra-day and inter-day precisions (based on the relative standard deviation, n =3) of the PGR derivatives were under 3.1% and 5.3% respectively and the accuracies of the method for the PGRs were in the range from 89.3% to 102.3%. The developed method was successfully applied to analyze PGRs residues in fruit samples. The proposed method is proved to be simple, environment-friendly and inexpensive and it is feasible to directly use UIO-67 as sorbent to extract targets by varying conditions. [ABSTRACT FROM AUTHOR]

Abstract: Determination of total thyroxine in human serum using hollow fiber liquid-phase microextraction (HF-LPME) has been accomplished for the first time. HF-LPME serves as an inexpensive sample pretreatment and the cleanup method that is nearly solvent-free. Thyroxine was extracted through a water immiscible organic solvent immobilized in the wall pores of a polypropylene hollow fiber into 20μl of an aqueous acceptor phase inside the lumen of the hollow fiber. This technique produced extracts that had comparable cleanness with those obtained using solid-phase extraction (SPE). Serum samples with endogenous thyroxine were spiked with isotopically-labeled thyroxine and analyzed by liquid chromatography–tandem mass spectrometry after HF-LPME extraction. Extraction parameters including the organic phase, acid/base concentration of acceptor phase, stirring speed and extraction time were optimized. The calibration range was found to be linear over 1–1000ng/g with the limit of detection (LOD) of 0.3 ng/g. For quantification of total thyroxine in human serum, 6 subsamples were prepared and the results indicated very good precision with a relative standard deviation of <1.3%. The difference from the SPE method was less than 1.2%, with independent t-test showing insignificant bias. Two reference materials of human serum were analyzed, and our obtained values were compared with the reference values. The results showed very good precision with RSD around 0.2% and the deviation from the reference values were −3.1% and −2.1%. The newly developed method is precise, accurate, inexpensive, and environmentally friendly. [Copyright &y& Elsevier]

Abstract: Alzheimer's disease (AD) is still being recognized today as an unmet medical need. Currently, there is no cure and early preclinical diagnostic assay available for AD. Therefore much attention is now being directed at the development of novel methods for quantitative determination of AD biomarkers in the cerebrospinal fluid (CSF). Here, we describe the liquid chromatography–tandem mass spectrometry method for determination of 5-hydroxytryptamine (SER), 5-hydroxyindoleacetic acid (5-HIAA), homovanilic acid (HVA), noradrenaline (NADR), adrenaline (ADR), dopamine (DA), glutamic acid (Glu), γ-aminobutyric acid (GABA), 3,4-dihydroxyphenylacetic acid (DOPAC) and histamine (HIS) in cerebrospinal fluid (CSF) from the rat model for human tauopathy. The benzoyl chloride was used as pre-column derivatization reagents. Neurotransmitters and metabolites were analysed on ultra performance liquid chromatography (UPLC) on C18 column in combination with tandem mass spectrometry. The method is simple, highly sensitive and showed excellent linearity with regression coefficients higher than 0.99. The accuracy was in a range of 93–113% for all analytes. The inter-day precision (n=5 days), expressed as %RSD, was in a range 2–10% for all analytes. Using this method we detected significant changes of CSF levels of two important neurotransmitters/metabolites, ADR and 5-HIAA, which correlates with progression of neurodegeneration in our animal model. [Copyright &y& Elsevier]

Abstract: This paper describes development and validation of a simple and efficient bioanalytical procedure for simultaneous determination of phenobarbital and carbamazepine in human serum samples using high performance liquid chromatography with photodiode-array detection (HPLC–DAD) regarding a fast elution methodology in less than 5min. Briefly, this method consisted of a simple deproteinization step of serum samples followed by HPLC analysis on a Bonus-RP column using an isocratic mode of elution with acetonitrile/K2HPO4 (pH=7.5) buffer solution (45:55). Due to the presence of serum endogenous components as non-calibrated components in the sample, second-order calibration based on multivariate curve resolution–alternating least squares (MCR–ALS), has been applied on a set of absorbance matrices collected as a function of retention time and wavelengths. Acceptable resolution and quantification results were achieved in the presence of matrix interferences and the second-order advantage was fully exploited. The average recoveries for carbamazepine and phenobarbital were 89.7% and 86.1% and relative standard deviation values were lower than 9%. Additionally, computed elliptical joint confidence region (EJCR) confirmed the accuracy of the proposed method and indicated the absence of both constant and proportional errors in the predicted concentrations. The developed method enabled the determination of the analytes in different serum samples in the presence of overlapped profiles, while keeping experimental time and extraction steps at minimum. Finally, the serum concentration levels of carbamazepine in three time intervals were reported for morphine-dependents who had received carbamazepine for treating their neuropathic pain. [Copyright &y& Elsevier]

A mixed matrix membrane (MMM), based on carbon nanotubes (CNTs) and hollow fiber (HF), was prepared and combined with solid phase microextraction (SPME) mode to determine strychnine and brucine in urine. This MMM was prepared by dispersing CNTs in water via surfactant assistance, and then immobilizing CNTs into the pores of HF by capillary forces and sonification. The prepared carbon nanotubes reinforced hollow fiber (CNTs–HF) was subsequently wetted by a few microliters of organic solvent (1-octanol), and then applied to extract the target analytes in direct immersion sampling mode. After extraction, analytes were desorbed via ultrasonic-assisted effect, and then detected via high-performance liquid chromatography (HPLC). To achieve the highest extraction efficiency, main extraction parameters such as the type and amount of surfactant, the diameter and doping level of CNTs, extraction time, desorption condition, pH value, stirring rate and volume of the donor phase were optimized. Under the optimum extraction conditions, the method showed good linearity ranges with correlation coefficients higher than 0.9990, good repeatability and batch-to-batch reproducibility with relative standard deviations (RSDs) less than 6% and 5% for strychnine and brucine, respectively, and low limits of detection (0.7 and 0.9µgL−1 for strychnine and brucine, respectively). The recoveries were in the range of 83.81–116.14% at three spiked levels. The developed method was successfully applied to real urine sample with mean relative recoveries of 94.28% and 91.30% for strychnine and brucine, respectively. The developed method shows comparable results against reference methods and is a simple, green, and cost-effective microextraction technique. [ABSTRACT FROM AUTHOR]

A novel amide-bonded silica stationary phase was prepared starting from N-Boc-phenylalanine, cyclohexylamine and spherical silica gel (4µm, 60Å). The amide ligand was synthesised with high yield. The resulting amide bonded stationary phase was characterised by SEM, IR and elemental analysis. The resulting selector bearing a polar amide group is used for the reversed-phase chromatography separation of different classes of thirteen phytohormones (plant hormones). The chromatographic behaviours of these analytes on the amide-silica stationary phase were compared with those of RP-C18 column under same conditions. The effects of different separation conditions, such as mobile phase, pH value, flow rate and temperature, on the separation and retention behaviours of the 13 phytohormones in this system were studied. The optimum separation was achieved using reversed-phase HPLC gradient elution with an aqueous mobile phase containing pH=6.85 potassium phosphate buffer (20mM) and acetonitrile with a 22°C column temperature. Under these experimental conditions, the 12 phytohormones could be separated and detected at 230 or 270nm within 26min. [ABSTRACT FROM AUTHOR]

Abstract: Arsenic is an element widely present in nature. Additionally, it may be found as different species in several matrices and therefore it is one of the target elements in chemical speciation. Although the number of studies in terrestrial plants is low, compared to matrices such as fish or urine, this number is raising due to the fact that this type of matrix are closely related to the human food chain. In speciation analysis, sample preparation is a critical step and several extraction procedures present drawbacks. In this review, papers dealing with extraction procedures, analytical methods, and studies of species conservation in plants cultivated in terrestrial environment are critically discussed. Analytical procedures based on extractions using water or diluted acid solutions associated with HPLC–ICP–MS are good alternatives, owing to their versatility and sensitivity, even though less expensive strategies are shown as feasible choices. [Copyright &y& Elsevier]

Abstract: Cloud-point extraction (CPE), an easy, safe, environmentally friendly, rapid and inexpensive methodology for preconcentration and separation of trace metals from aqueous solutions has recently become an attractive area of research and an alternative to liquid–liquid extraction. Moreover, it provides results comparable to those obtained with other separation techniques and has a greater potential to be explored in improving detection limits and other analytical characteristics over other methods. A few reviews have been published covering different aspects of the CPE procedure and its relevant applications, such as the phenomenon of clouding, the application in the extraction of trace inorganic and organic materials, as well as pesticides and protein substrates from different sources, or incorporation of CPE into an FIA system. This review focuses on general properties of the most frequently used organic ligands in cloud-point extraction and on literature data (from 2000 to 2012) concerning the use of modern techniques in determination of metal ions' content in various materials. The article is divided according to the class of organic ligands to be used in CPE. [Copyright &y& Elsevier]

Abstract: Therapeutic drug monitoring (TDM) may be very useful in the clinical management of antiepileptic drug therapy for multiple reasons, such as individual variability, metabolism, genetic factors or drug–drug or drug–food interactions. In addition, TDM is helpful to study the variation in pharmacokinetics that occurs between individuals. Here, we describe a rapid assay using ultra-performance liquid chromatography–electrospray ionization tandem mass spectrometry to measure the antiepileptic drugs lacosamide, lamotrigine, levetiracetam, primidone, topiramate, and zonisamide. After the addition of internal standards (ISs) and protein precipitation of serum or plasma, 1μl of sample was separated on a 2.1×50mm reverse phase column (Waters, Acquity UPLC BEH Phenyl, 1.7μm). Analytes were then ionized and detected by electrospray ionization mass spectrometry with multiple reaction monitoring. Runtime was 2.5min per injection. Matrix effects were investigated by systematical ion suppression and in-source fragmentation experiments. The calibration curves of the 6 antiepileptic drugs were linear over the working range between 0.05 and 50mg/L (r>0.99). The limit of detection (LOD) was <0.05mg/L, whereas the limit of quantification (LLOQ) was 0.10mg/L of all drugs measured in the assay. The intraassay and interassay coefficients of variation for all compounds were <15% for very low concentration (0.1mg/L) and <8% in the clinically relevant concentration range (>1.0mg/L). Mean recoveries were between 87.8 and 98.6% for all drugs. There were no significant ion suppressions detected at the elution times of the analytes. The mean differences between serum and heparinized plasma values were less than 6% for the 6 antiepileptic drugs. All drugs were stable in serum at −20°C, 4°C, and even at RT for at least 1 month. In summary, a specific and sensitive stable isotope dilution UPLC-MS/MS method was developed and validated for routine clinical monitoring of lacosamide, lamotrigine, levetiracetam, primidone, topiramate, and zonisamide. [Copyright &y& Elsevier]

Abstract: Corn steep liquor (CSL), an important raw material with high nutritional value, serves as a nitrogen source in the fermentation industry. The CSL quality directly affects the yield and quality of fermentation products. In this work, a fingerprinting technique was used to identify the potential markers of CSL. Forty-two CSL samples from different manufacturers were profiled by ultra-performance liquid chromatography with tandem quadrupole time-of-flight mass spectrometry. Sixteen compounds, almost all of which were amino acids and their derivatives, were considered as the potential markers. Then, o-phthalaldehyde-9-fluorenylmethyl chloroformate precolumn derivatization by high-performance liquid chromatography was performed to identify the free amino acids in CSL. Principal component analysis (PCA) was used to distinguish among the samples from different manufacturers. The results demonstrated that the fingerprinting technique combined with PCA analysis was a powerful tool for determining the CSL quality. [Copyright &y& Elsevier]

Abstract: A simplified, rapid, and selective liquid chromatography–tandem mass spectrometry method for the determination of the activities of cytochrome P450 (CYP) enzymes and UDP-glucuronosyltransferases (UGTs) in two separate settings was developed and successfully applied to 8 CYP isoenzymes and UGT2B7 enzyme activities in rat liver microsomes. The triple-quadrupole mass spectrometric detection was operated in positive mode for the probe metabolites: CYP1A2 (resorufin), CYP2B6 (hydroxybupropion), CYP2C19 (5-hydroxyomeprazole), CYP2D6 (dextrophan), CYP3A4 (6β-hydroxytestosterone), and UGT2B7 (morphine-3-glucuronide); also in negative mode for CYP2C9 (4-hydroxytolbutamide), CYP2E1 (6-hydroxychloroxazone), and CYP4A (hydroxylauric acid). The metabolic reactions were terminated with acetonitrile, containing metoprolol and acetaminophen as the internal standard for positive and negative ion electrospray ionization, respectively. The method was validated over the concentration range of 25–2500ng/mL for 5-hydroxyomeprazole, dextrophan, hydroxylauric acid, and morphine-3-glucuronide; 5–500ng/mL for resorufin; 3–300ng/mL for hydroxybupropion; 10–1000ng/mL for 4-hydroxytolbutamide; 40–4000ng/mL for 6-hydroxychloroxazone; and 63–6300ng/mL for 6β-hydroxytestosterone. All of the extraction recoveries of these analytes were greater than 85%, except for hydroxylauric acid at mid-concentration with a recovery of 83.2%±3.2%. The matrix effects were between 85.8% and 119.9%; the respective within- and between-run precisions were 0.9–12.0% and 2.0–13.9%; and the within- and between-run accuracy levels were 0.6–17.2% and 0.1–15.1%, respectively, for all these analytes. All of the analytes were stable during the assay and storage in the liver microsomes of Sprague-Dawley rats. The measurement activity of multiple enzymes was feasible using a cocktail approach. This method proved to be a robust, fast, accurate, specific and sensitive assay, and was successfully used to investigate in vivo enzyme activities of 8 major CYP isoenzymes and UGT2B7 in Sprague-Dawley rats with fatty livers. By the end of the eighth week, the CD-fed induced fatty liver rats showed a significant decrease in the activities of CYP1A2 and UGT2B7 as compared to the standard diet group. [Copyright &y& Elsevier]

Abstract: A novel method for the simultaneous separation and determination of four benzimidazole fungicides (i.e., carbendazim, fuberidazole, thiophanate-methyl and thiophanate) in high salinity samples was developed by using salting-out assisted liquid–liquid extraction (SALLE) via water-miscible acetonitrile as the extractant coupled with high-performance liquid chromatography. Box–Behnken design and response surface were employed to assist the optimization of SALLE conditions, including volume of salting-out solvent, the pH of sample solution and salting-out solvent as variable factors. The optimal salting-out parameters were obtained as follows: 2mL of acetonitrile was added to 2mL of sample solution with pH=4 and then 2mL salting-out solvent containing 5molL−1 sodium chloride at a pH of 7 was added to the solution for extraction. This procedure afforded a convenient and cost-saving operation with good cleanup ability for the benzimidazole fungicides, such as good linear relationships (R>0.996) between peak area and concentration from 2.5ngmL−1 to 500ngmL−1, low limits of detection between 0.14ngmL−1 and 0.38ngmL−1 and the intra-day precisions of retention time below 1.0%. The method recoveries obtained at fortified three concentrations for three seawater samples ranged from 60.4% to 99.1%. The simple, rapid and eco-benign SALLE based method proved potentially applicable for trace benzimidazole fungicides analysis in high salinity samples. [Copyright &y& Elsevier]

Abstract: This work presents the development of a liquid chromatographic method based on modeling entire fast scan fluorimetric detection second-order data with the multivariate curve resolution alternating least squares algorithm, for the simultaneous determination of five marker pteridines in urine samples. The modeling strategy involves the building of a single MCR-ALS model composed of matrices augmented in the spectral mode, i.e. time profiles remain invariant while spectra may change from sample to sample. This approach allowed us to separate and determine the whole analytes at once. The developed approach enabled us to determine five of the most important metabolic disorder marker pteridines: biopterin, neopterin, isoxanthopterin, pterin and xanthopterin, three of them presenting emission spectra with the same emission wavelength maxima. In addition, some of these analytes present overlapped time profiles. As a consequence of using the entire data sets, a considerable reduction of the data processing experimental time can be achieved. Results are compared with a previous strategy in which data were split in five different regions, and information about the figures of merit of the new strategy compared with the previously reported strategy is reported. [Copyright &y& Elsevier]

Abstract: A novel method combining high performance liquid chromatography (HPLC) fingerprint and simultanous quantitative analysis of multiple acitve components was developed and validated for quality evaluation of one type of traditional Chinese medicine preparations: Shuang-huang-lian (SHL) oral liquid formulation. For fingerprint analysis, 45 peaks were selected as the common peaks to evaluate the similarities among several different SHL oral liquid preparations collected from manufacturers. Additionally, simultanous quantification of eleven markers, including chlorogenic acid, caffeic acid, rutin, forsythiaside, scutellarin, baicalin, forsythin, luteoloside, apigenin, baicalein and wogonin, was performed. Statistical analysis of the obtained data demonstrated that our method has achieved desired linearity, precision and accuracy. Finally, concentrations of these eleven markers in SHL oral liquid prepared by different manufacturers in China were determined. These results demonstrated that the combination of HPLC chromatographic fingerprint and simultaneous quantification of multi-ingredients offers an efficient and reliable approach for quality evaluation of SHL oral liquid preparations. [Copyright &y& Elsevier]

Abstract: An analytical protocol for the isolation and quantification of indole-3-acetic acid (IAA) and its amino acid conjugates was developed. IAA is an important phytohormone and formation of its conjugates plays a crucial role in regulating IAA levels in plants. The developed protocol combines a highly specific immunoaffinity extraction with a sensitive and selective LC–MS/MS analysis. By using internal standards for each of the studied compounds, IAA and seven amino acid conjugates were analyzed in quantities of fresh plant material as low as 30mg. In seeds of Helleborus niger, physiological levels of these compounds were found to range from 7.5nmolg−1 fresh weight (IAA) to 0.44pmolg−1 fresh weight (conjugate with Ala). To our knowledge, the identification of IAA conjugates with Gly, Phe and Val from higher plants is reported here for the first time. [Copyright &y& Elsevier]

Abstract: A new and fast hollow fiber based liquid phase microextraction (HF-LPME) method using volatile organic solvents coupled with high-performance liquid chromatography (HPLC) was developed for determination of aromatic amines in the environmental water samples. Analytes including 3-nitroaniline, 3-chloroaniline and 4-bromoaniline were extracted from 6mL basic aqueous sample solution (donor phase, NaOH 1molL−1) into the thin film of organic solvent that surrounded and impregnated the pores of the polypropylene hollow fiber wall (toluene, 20μL), then back-extracted into the 6μL acidified aqueous solution (acceptor phase, HCl 0.5molL−1) in the lumen of the two-end sealed hollow fiber. After the extraction, 5μL of the acceptor phase was withdrawn into the syringe and injected directly into the HPLC system for the analysis. The parameters influencing the extraction efficiency including the kind of organic solvent and its volume, composition of donor and acceptor phases and the volume ratio between them, extraction time, stirring rate, salt addition and the effect of the analyte complexation with 18-crown-6 ether were investigated and optimized. Under the optimal conditions (donor phase: 6mL of 1molL−1 NaOH with 10% NaCl; organic phase: 20μL of toluene; acceptor phase: 6μL of 0.5molL−1 HCl and 600mmolL−1 18-crown-6 ether; pre-extraction and back-extraction times: 75s and 10min, respectively; stirring rate: 800rpm), the obtained EFs were between 259 and 674, dynamic linear ranges were 0.1–1000μgL−1 (R >0.9991), and also the limits of detection were in the range of 0.01–0.1μgL−1. The proposed procedure worked very well for real environmental water samples with microgram per liter level of the analytes, and good relative recoveries (91–102%) were obtained for the spiked sample solutions. [Copyright &y& Elsevier]

Abstract: A high-performance liquid chromatographic method was proposed for the separation of relative impurities in industrial 3-methylflavone-8-carboxylic acid (MFCA) and its intermediate methyl 3-propionylsalicylate (MPS). Benzoic acid (BA), MPS, 6-chloro-3-methylflavone-8-carboxylic acid (MFCA-Cl) and methyl 5-chloro-3-propionylsalicylate (MPS-Cl) in MFCA, and MPS-Cl in MPS were respectively quantified by an external standard method. As results showed, the linearity of standard curves was excellent with the relative coefficients of over 0.999 for all the detected components, and the intra- and inter-day precisions of impurities determination were satisfactory with the relative standard deviation of not more than 8.0%. Under the selected experimental condition, the chromatographic fingerprints of MFCA and MPS were drawn synthetically, and the transfer of impurities in the stepwise reactions of MFCA manufacture was elucidated. The fingerprints have great potential in instructing the production of MFCA for industrial use and in conducting the conversion of relative impurities. [Copyright &y& Elsevier]

Abstract: A novel fluorescent-activated ester, 8-phenyl-(4-oxy-acetic acid N-hydroxysuccinimidyl ester)-4,4-difluoro-1,3,5,7-tetramethyl-4-bora-3a,4a-diaza-s-indacene (TMPAB-OSu) has been designed and synthesized for amine labeling in HPLC. Being used 11 aliphatic amines as the models, the derivatization conditions were optimized. In 0.2mol/l borate buffer (pH 8.8), amines reacted with TMPAB-OSu at 30°C to form the derivatives in 10min. The fluorescent quantum yield of TMPAB-OSu and its amine derivatives are high even compared with fluorescein. The separation of these amine derivatives was achieved with a C8 column and gradient elution by using 0.1mol/l sodium acetate buffer (pH 5.0) and methanol. With fluorescence detection at an emission wavelength of 509nm and an excitation wavelength of 497nm, the detection limits of aliphatic amines were 2–18fmol, at a signal-to-noise ratio of 3:1. The proposed TMPAB-OSu-based HPLC method has been applied to the analysis of urine samples of health, hepatic and renal patients and lake water. Recoveries from different matrices are from 96 to 104%, depending on the sample investigated. [Copyright &y& Elsevier]

Abstract: A solid–liquid extraction procedure followed by reversed-phase high-performance liquid chromatography (RP-HPLC) coupled with a photodiode array detector (DAD) for the determination of polyphenols in freeze-dried apple peel and pulp is reported. The extraction step consists in sonicating 0.5g of freeze-dried apple tissue with 30mL of methanol–water–acetic acid (30:69:1, v/v/v) containing 2g of ascorbic acid/L, for 10min in an ultrasonic bath. The whole method was validated, concluding that it is a robust method that presents high extraction efficiencies (peel: >91%, pulp: >95%) and appropriate precisions (within day: R.S.D. (n = 5) <5%, and between days: R.S.D. (n = 5) <7%) at the different concentration levels of polyphenols that can be found in apple samples. The method was compared with one previously published, consisting in a pressurized liquid extraction (PLE) followed by RP-HPLC-DAD determination. The advantages and disadvantages of both methods are discussed. [Copyright &y& Elsevier]

Currently, no standard method exists for analyzing insensitive munition (IM) compounds in environmental matrices, with or without concurrent legacy munition compounds, resulting in potentially inaccurate determinations. The primary objective of this work was to develop new methods of extraction, pre-concentration, and analytical separation/quantitation of 17 legacy munition compounds along with several additional IM compounds, IM breakdown products, and other munition compounds that are not currently included in U. S. Environmental Protection Agency (EPA) Method 8330B. The eight additional compounds included were nitroguanidine, 3-nitro-1,2,4-triazol-5-one, picric acid, 2,4-dinitroanisole, 2,4-dinitrophenol, 2-nitrophenol, 4-nitrophenol, and new surrogate ortho -nitrobenzoic acid (o -NBA). Analytical methods were developed to enable sensitive, simultaneous detection and quantitation of the 24 IM and legacy compounds, including two orthogonal high-performance liquid chromatography (HPLC) column separations with either ultraviolet (UV) or mass spectrometric (MS) detection. Procedures were developed for simultaneous extraction of all 24 analytes and two surrogates (1,2-dinitrobenzene, 1,2-DNB; o -NBA) from high- and low-level aqueous matrices and solid matrices, using acidification, solid phase extraction (SPE), or solvent extraction (SE), respectively. For low-level aqueous samples extracted by SPE, all compounds were recovered within current Department of Defense Quality Systems Manual (DoD QSM) Ver5.3 accepted limits for aqueous samples analyzed by EPA Method 8330B (57–135%), except NQ, which was consistently recovered at approximately 50%. Likewise, all compounds were recovered from six geographically/geochemically unique soil types within current QSM accepted limits for solid samples analyzed by EPA Method 8330B (64–135%). Further, the majority of compounds were recovered from four tissue types within current limits for solids, with generally low recovery only for Tetryl (from 4 to 62%). A preparatory chromatographic interference removal procedure was adapted for tissue extracts, as various analytical interferences were observed for all studied tissue types. Image 1 • Co-extraction of legacy and insensitive munitions (IM) from waters, soils, and tissues. • EPA Method 8330B adapted to add NQ, NTO, DNAN, DNP, NP's, picric acid, and a new surrogate. • High-level direct injection and low-level solid phase extraction methods for waters. • Distinict solvent extraction methods for soils/sediments and tissues, with associated interference reduction method for tissues. • Two orthogonal HPLC-based separations, with UV or MS detection. [ABSTRACT FROM AUTHOR]