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Peak broadening in ion mobility (IM) is a relatively predictable process and abnormally broad peaks can be indicative of the presence of unresolved species. Here, we introduce a new ion mobility peak fitting (IM_FIT) software package for automated and systematic determination of traveling wave ion mobility (TWIM) unresolved species. To identify IM unresolved species, the IM_FIT software generates a trend line by plotting ions' mobility peak widths as a function of their arrival times. Utilizing user-defined thresholds, IM_FIT allows for automated and rapid detection of ions that deviate from the peak width trend line. To demonstrate the advantages of IM_FIT for automated detection of IM unresolved species, IM-mass spectrometry (IM-MS) data from a sample mixture containing polypropylene glycol and multiple peptides were analyzed. A total of 14 out of the 34 observed singly-charged IM peaks above 5% relative abundance ( i.e., signal-to-noise ratios above ∼200) were tagged as potentially co-eluting ions by IM_FIT. Subsequently, the 14 IM peaks tagged as potentially unresolved (presumably, peaks corresponding to co-eluting compounds), were further analyzed by automated IM deconvolution (AIMD), liquid chromatography-IM-MS (LC-IM-MS), and/or ultra-high resolution mass spectrometry. Using the aforementioned techniques, more than 85% of the tagged IM peaks (12 out of 14) were confirmed to contain co-eluting ions. As an additional new finding, IM_FIT facilitated the discovery of an unexpected sequence-scrambled y-type fragment ion. [ABSTRACT FROM AUTHOR]

Abstract: In this work, it has been extended to methanol:water mobile phases, the use of a background correction method for on-line LC–FTIR measurements named Univariate background correction based on the use of a reference spectra matrix (UBC-RSM) and absorbance ratios. It permits to overcome the problem related to spectral changes occurring during the gradient elution, which in the past limited the on-line coupling of LC and FTIR to isocratic elutions. The combined use of the aforementioned background correction technique in on-line isocratic and gradient LC–FTIR, and partial least squares (PLS) has been applied for the search of the critical conditions for polymers. Polyethylenglycol (PEG) has been used as a model example and results found fitted well with previously published ones. [Copyright &y& Elsevier]

Abstract: A selective and sensitive liquid chromatography coupled with triple stage quadruple tandem mass spectrometry (HPLC/TSQ-MS/MS) was developed and validated for simultaneous quantification of calycosin-7-O-β-d-glycoside (CCSG), formononetin-7-O-β-d-glycoside (Ononin) and (6R,10R)-9,10-dimethoxypterocarpan-3-O-β-d-glycoside (DPG) in rabbit plasma. Plasma samples were extracted with solid-phase extraction (SPE), separated on an Inertsil ODS-3 column and detected by tandem mass spectrometry with electrospray ionization (ESI) interface in positive selective reaction monitoring (SRM) mode. 3,7,8-Trimethoxy-xanthone-1-O-primaverose was used as internal standard (IS) for quantitative measurement. For each analyte, one major product ion was chosen and used for screening of it. Calibration curves were generated over the range of 2–1000ngmL−1 with the correlation coefficients greater than 0.99 by using a weighted (1/χ) least squares linear regression. The method had the lower limit quantification of 0.15, 0.21 and 0.19 for CCSG, Ononin and DPG, respectively, with precision less than 20%. The intra- and inter-day precisions ranged from 2.48 to 6.38% and 4.81 to 11.78% (R.S.D.%), respectively. This assay is suitable for determining the above three trace glycosides in rabbit plasma simultaneously and thus investigating the pharmacokinetics of glycosides from Astragalus mongholicus extract in rabbits. [Copyright &y& Elsevier]

Abstract: An improved analytical method for determination of human pharmaceuticals in natural and wastewaters with ngL−1 sensitivity is presented. The method is applicable to pharmaceuticals from a wide range of therapeutic classes including antibiotics, analgesics, anti-inflammatories and anti-cancer compounds. Pharmaceuticals were extracted from waters using solid-phase extraction, and after concentration, analysed by high performance liquid chromatography with tandem mass spectrometric detection (HPLC–MS/MS). Identification of each compound was secured using retention time and by the selected reaction monitoring of two transitions, one of which was additionally used for quantification. Limits of detection ranged from 0.03 to 0.96ngL−1 and were up to two orders of magnitude lower than those of previously published methods. The method was validated using spiked samples prepared from tap, river and sea water as well as wastewater effluents, collected from the North of Scotland. Analysis of wastewater effluents revealed the presence of mefenamic acid, ibuprofen, erythromycin, diclofenac and trimethoprim. None of the selected pharmaceuticals were detected in river, tap or sea water samples. [Copyright &y& Elsevier]

Abstract: The use of gestagens in animal fattening is prohibited within the European Union. Recently, the use of spectrometric methods for the detection and confirmation of banned substances was made obligatory. Therefore, conventional high-performance liquid chromatographic (HPLC) methods have been superseded. It has been possible to couple a previously described HPLC method for the determination of acetyl-gestagens in kidney fat to tandem mass spectrometry (LC-MS/MS). The decision limits CCα and the detection capability CCβ are found to be below the minimum required performance limit (MRPL) established for medroxyprogesterone acetate (MPA) at 1μgkg−1. The calculated values for CCα are as follows: megestrol acetate (MGA)—0.15μgkg−1, melengesterol acetate (MLA)—0.15μgkg−1, chlormadinone acetate (CMA)—0.37μgkg−1 and for medroxyprogesterone acetate (MPA)—0.24μgkg−1. The CCβ values for these compounds have been determined as 0.19, 0.19, 0.47 and 0.32μgkg−1, respectively. [Copyright &y& Elsevier]

Abstract: Cylindrospermopsin (CYN) was determined by liquid chromatography/electrospray ionization-mass spectrometry (LC/ESI-MS) using 2-[4-(2-hydroxyethyl)-1-piperazinyl]ethanesulfonic acid (HEPES) as the internal standard. In the selected ion monitoring of LC/ESI-MS, m/z 414 for CYN and 237 for HEPES were monitored using the negative mode; the retention times of CYN and HEPES were 12.41 and 14.21min, respectively. CYN was determined from peak area ratios of m/z 414/237. By the treatment of an anion exchange cartridge using a buffer at pH 10.5, CYN was isolated and condensed. No interfering peak was observed. Linearity of this method was observed at the range of 0.10–31.12ng. Total coefficients of variation were 5.1 and 2.9% at 104 and 1038μgCYNL−1. The quantitative limit at a signal-to-noise (S/N) ratio of 10 was 0.16ng. CYN concentration in natural waters is low. CYN in waters should be condensed for determination. This method including the treatment for isolation and condensation of CYN is useful for determination of CYN in environmental and/or drinking waters. [Copyright &y& Elsevier]

Abstract: The present article aims to develop a new extraction procedure to improve the determination of quinolones in chicken muscle. This new determination method was validated using liquid chromatography–ultraviolet detection (LC–UV) and liquid chromatography–mass spectrometry detection (LC–MS), which has special bearing on stability studies. The results obtained by using the method were compared with the results obtained with a previous methodology. The new extraction procedure presents a sensitivity low enough to determine concentration of these drugs below the permissible maximum residue limits (MRL) in chicken muscle and is less time consuming than the previous methodology. [Copyright &y& Elsevier]

Abstract: Urine, a blood filtrate produced by the urinary system, is an ideal bio-sample and a rich source of biomarkers for diagnostic information. Many components in urine are useful in clinical diagnosis, and urinary proteins can be strong indication for many diseases such as proteinuria, kidney, bladder and urinary tract diseases. To enhance our understanding of urinary proteome, the urine proteins were prepared by different sample cleanup preparation methods and identified by nano-high performance liquid chromatography electrospray ionization tandem mass spectrometry followed by peptide fragmentation pattern. The experimental results demonstrated that a total of 2283 peptides, corresponding to 311 unique proteins, were identified from human urine samples, in which 104 proteins with higher confidence levels. The present study was designed to establish optimal techniques to create a proteomic map of normal urinary proteins. Also, a discussion of novel approaches to urine protein cleanup and constituents is given. [Copyright &y& Elsevier]

Abstract: High-performance liquid chromatography coupled with electrospray tandem mass spectrometry (HPLC/ESI–MS/MS) was used to identify C-21 steroidal glycosides with immunological activities in roots of Cynanchum chekiangense. In the MS/MS spectra, fragmentation reactions of the [M+Na]+ were recorded to provide structural information about the glycosyl and aglycone moieties. To further confirm the fragments structures, off-line Fourier transform ion cyclotron resonance tandem mass spectrometry (FT-ICR–MS/MS) was also performed. In the study, four known steroidal glycosides cynascyroside C, chekiangensosides A and B, glaucoside H, and four novel steroidal glycosides chekiangensosides C, D, E and chekiangensoside A isomer were identified based on mass spectral data, NMR spectral data and standards. This is the first report on identifying steroidal glycosides in roots of C. chekiangense by HPLC/ESI–MS/MS directly, which could save time and material consuming efforts in traditional phytochemistry analysis. [Copyright &y& Elsevier]

Abstract: In this work the development of a method to determine semicarbazide (SEM) in fresh whole egg and in whole egg and egg white powders as those used in the food industry, by using LC–MS/MS is described. The method is based on a recently validated one for the determination of SEM in baby food. SEM is extracted from egg with 0.2molL−1 hydrochloric acid and derivatised with 2-nitrobenzaldehyde. The extract is neutralised and purified by passing through a solid phase extraction (SPE) cartridge. The 2-nitrobenzaldehyde derivative is eluted with ethyl acetate. The eluate is evaporated to dryness and the residue re-dissolved in methanol:water mobile phase. SEM is determined by reversed-phase LC–MS/MS. The “in-house” validation of this method has been performed taking into account the “Harmonized guidelines for single-laboratory validation of methods of analysis” (IUPAC Technical report) and the Commission Decision (2002/657/EC). The performance characteristics of the method were established by in-house validation procedures employing assays with standard solutions, sample blanks and spiked samples. Linearity, matrix effect, trueness, precision, selectivity, limits of detection and of quantification were determined. The fitness for purpose of this method was assessed based on its performance characteristics. LOD''s of 0.15 and 0.4μgkg−1 for whole fresh egg and industrial egg powders, respectively, were obtained. The LOQ for fresh whole egg was 0.2μgkg−1 and for industrial egg powders 0.8μgkg−1. Linear calibration curves were obtained in the ranges 1–100 and 0.8–400μgkg−1 for fresh whole egg and the egg powders, respectively. [Copyright &y& Elsevier]

Abstract: A simple and rapid pressurized liquid extraction (PLE) and high performance liquid chromatography–electrospray ionization tandem mass spectrometry (HPLC–ESI–MS/MS) method was developed for qualitative and quantitative determination of nucleosides, bases and their analogues in natural and cultured Cordyceps. The samples were extracted using PLE. The separation was achieved on a ZORBAX Eclipse XDB-C18 column with gradient elution of methanol and 5mM aqueous ammonium acetate as mobile phase. Target compounds were identified by characterizing their product ions, precursor ions and retention times. Quantitative analysis of investigated compounds were performed using time programmed selective ion monitoring (SIM) or selective reaction monitoring (SRM) with 10 segments in positive (negative for uridine) ion mode. The results showed that 43 bases, nucleosides and their analogues were detected in Cordyceps, of these 16 compounds were identified. The simultaneous determination of seven nucleosides and six bases in Cordyceps was achieved using PLE and HPLC–ESI–MS/MS method described above, which afforded good linearity, selectivity, precision, recovery, short analysis time as well as LOD and LOQ in the ng/ml range. [Copyright &y& Elsevier]

Abstract: Liquid chromatography with time-of-flight mass spectrometry (LC–TOF-MS) method has been developed for simultaneous confirmation by accurate mass measurement and quantitative determination of antibiotics (enrofloxacin, oxolinic acid, flumequine, erythromycin), fungicides (malachite green MG, leucomalachite green LMG) and parasiticide (emamectin benzoate) residues in edible portion of salmon. Confirmation of chemotherapeutant residues has been based on the system of identification points (IPs) established in the Commission Decision 2002/657/EC concerning the use of mass spectrometry (MS) techniques. A validation study on matrix is presented evaluating accuracy in terms of precision (λ ppm 0.83–1.15) and trueness (0.22–0.70Da). Limits of detection (LODs) and limits of quantification (LOQs) were in ranges of 1–3 and 3–9μg/kg, below the maximum residue limits (MRLs) established in current EU legislation (100–200μg/kg) for these chemotherapeutants. Considering the EU guidelines, decision limits (CCα) and detection capabilities (CCβ) were determined (ranges of 103–218 and 107–234μg/kg, respectively) for authorised substances. For no authorised compounds (MG and LMG), LODs were 2 and 1μg/kg, respectively, but exceed the MRPL (minimum required performance limit) established in the legislation which corresponds to the sum of MG and LMG (2μg/kg). Acceptable intra-day and inter-day variability, in terms of relative standard deviation (R.S.D.) of the analytical method, were obtained (2–15%). Linearity was demonstrated from the LOQs of the analytes to 600μg/kg (r >0.9991). The method has involved an extraction procedure based on solid–liquid extraction (SLE) with recoveries higher than 80% for most target chemotherapeutants, with exception of enrofloxacin (40%). [Copyright &y& Elsevier]

Abstract: We developed a sensitive and useful method for the determination of five fluoroquinolones (FQs), enoxacin, ofloxacin, ciprofloxacin, norfloxacin, and lomefloxacin in environmental waters, using a fully automated method consisting of in-tube solid-phase microextraction (SPME) coupled with liquid chromatography–tandem mass spectrometry (LC/MS/MS). These compounds were analysed within 7min by high-performance liquid chromatography (HPLC) using a CAPCELL PAK C8 column and aqueous ammonium formate (pH 3.0, 5mM)/acetonitrile (85/15, v/v) at a flow rate of 0.2mL/min. Electrospray ionization conditions in the positive ion mode were optimized for MS/MS detection. In order to optimize the extraction of FQs, several in-tube SPME parameters were examined. The optimum in-tube SPME conditions were 20draw/eject cycles of 40μL of sample at a flow-rate of 150μL/min, using a Carboxen 1010 PLOT capillary column as an extraction device. The extracted compounds were easily desorbed from the capillary by passage of the mobile phase. Using the in-tube SPME LC/MS/MS method, good linearity of the calibration curve (r ≥0.997) was obtained in the concentration range from 0.1 to 10ng/mL for all compounds examined. The limits of detection (S/N=3) of the five FQs ranged from 7 to 29pg/mL. The in-tube SPME method showed 60–94-fold higher sensitivity than the direct injection method (5μL injection). This method was applied successfully to the analysis of environmental water samples without any other pretreatment and interference peaks. Several surface waters and wastewaters were collected from the area around Asahi River, and ofloxacin was detected in wastewater samples of a sewage treatment plant and other two hospitals at 17.5–186.2pg/mL. The recoveries of FQs spiked into river water were above 81% for a 0.1 or 0.2ng/mL spiking concentration, and the relative standard deviations were below 1.9–8.6%. [Copyright &y& Elsevier]

Abstract: A previously described liquid-only cavity flow cell is used to assess the feasibility of improving absorbance detection limits in liquid chromatography (LC) using cavity ring-down spectroscopy (CRDS). In this miniaturized cavity there is an optical path length of only 2mm between the mirrors, which at the same time form the walls of the flow cell. Typical ring-down times are 65–75ns for the eluent blank. The performance of the presented flow cell compares favorably to conventional absorbance detection: the baseline noise is determined to be 2.7×10−6 A.U. using averaging over 1s. The concentration detection limits are between 15 and 20nM (injected concentrations) for compounds with a molar extinction coefficient of 1.0–1.4×104 M−1 cm−1 at the laser wavelength of 532nm. The baseline noise as well as the absolute concentration detection limit is lowered by a factor of 30 as compared to measurements with a typical conventional absorbance detector. With an extra band broadening of only 15%, the flow cell is suitable for LC analysis. [Copyright &y& Elsevier]

Abstract: A reversed-phase liquid chromatographic method with photo-diode array detection is presented for use in the determination of chloramphenicol. A new amide-based stationary phase prevents the interaction of the analyte with the residual silanol groups, thus avoiding the appearance of tailed peaks. Specificity was demonstrated by the retention characteristics, UV spectra and peak purity index. Linearity, precision, recovery and sensitivity were satisfactory. The procedure was applied to the analysis of residual chloramphenicol in different types of animal feed. Samples were extracted by using liquid–liquid extraction steps with organic solvents and, for the clean-up, solid-phase extraction using cartridges was applied. Detection limit in the samples using the proposed procedure was 0.7μgkg−1. [Copyright &y& Elsevier]

Abstract: A sensitive and novel HPLC–tandem mass spectrometric method has been developed for the estimation of tegaserod in human plasma using atorvastatin as internal standard. The methodology involved solid phase extraction (SPE) of the analyte from human plasma, using the Water''s Oasis® HLB 1cm3 (30mg) cartridges. The chromatographic separation was achieved within 5min on XTerra MS C18, 100mm×2.1mm i.d., 3.5μm analytical column with an isocratic mobile phase containing a mixture of acetonitrile and 0.2% formic acid in water (50:50, v/v) flowing through it at the rate of 0.3ml/min. Multiple reaction monitoring (MRM) transitions; m/z 302.2, 173.2 and 559.0, 439.7 were measured in positive mode for tegaserod and internal standard, respectively. A detailed validation of the method was performed as per USFDA guidelines. The standard curves were linear in the range 0.2–20.0ng/ml with the mean correlation coefficient more than 0.99. The absolute recovery for tegaserod was more than 70%. The method was simple, sensitive, precise, accurate and suitable for routine bioequivalence and pharmaco-kinetic studies. The method was successfully applied to the bioequivalence study of tegaserod tablets in healthy, male human subjects. [Copyright &y& Elsevier]

Abstract: A chemical confirmation method for the identification and quantification of five banned antibacterial growth promoters (AGPs) in animal feed was developed and in-house validated as part of the European Feedstuffs-RADIUS project . To complete the validation process a collaborative trial was performed by eleven laboratories within the European Union (EU) using the developed method. Laboratories were supplied with six animal feed samples. None of the participants reported any false non-compliant results on these samples. Neither where there any false compliant results for four out of five compounds. These data proved the procedure to be robust and an excellent means of controlling misuse of the banned antibacterial growth promoters. During a small feed survey, a selection (n =614) of animal feed samples were screened with a multi-antibiotic ELISA method that was developed in the same EU project and non-compliant samples were submitted to liquid chromatography-tandem mass spectrometry (LC–MS/MS) confirmation. The results from this confirmatory analysis indicated that the LC–MS/MS method will be a valuable tool in helping to determine the origin of the detected antibacterial compounds and that animals are still receiving tylosin in concentrations that are in the same range as the now banned AGP concentrations. [Copyright &y& Elsevier]

Abstract: A robust and fitted routine method resulting from an analytical optimisation has been applied for the determination of acrylamide in several foods including mainly potato and cereal products. For the sample treatment, different materials were evaluated for filtration and purification of the extract. To increase the performances in terms of sensitivity, a preconcentration to small volume was introduced before liquid chromatography coupled to tandem mass spectrometry analysis on a μ-Bondapak C18 column using d3-acrylamide as internal standard. For identification, relative retention time and two diagnostic ions were monitored. A limit of detection of 10μgkg−1, a limit of quantitation of 20μgkg−1, mean recoveries ranging from 100 to 115%, coefficients of variation from 1.36 to 8.06% for repeatability and from 3.3 to 18.2% for reproducibility within the laboratory and a measurement uncertainty of 42% were obtained during an in-house validation procedure. Results of tests, validation data and Z-score obtained during participation to proficiency studies are presented. [Copyright &y& Elsevier]

Abstract: We developed a new analysis method for the nine N-methyl carbamate pesticides in fruits and vegetables using ESI LC/MS/MS with direct sample injection into a short column. After extraction of the pesticides with ethyl acetate from sample, the extract is evaporated to dryness and redissolved in ultra pure water before injection into LC/MS/MS. The method needs no cleanup steps. The average recoveries from fruits and vegetables fortified at the level of 0.01μg/g ranged from 56.0 to 119.1% with the coefficients of variation ranging from 0.2 to 7.6% for intra-day (n =5×3 days) and from 0.8 to 18.4% for inter-day (n =15). At the fortified level of 0.5μg/g, the recoveries ranged from 67.7 to 119.3% with the coefficients of variation ranging from 0.5 to 7.8% for intra-day (n =5×3 days) and from 0.9 to 14.8% for inter-day (n =15). The method is considered to be satisfactory for the monitoring of the carbamate pesticide residues in fruits and vegetables, suggesting that the present method is applicable to other pesticide residues in foods. [Copyright &y& Elsevier]

Abstract: The metabolism of selenium (Se) in the human body has yet not completely been unravelled and hence, an efficient method for characterization and on-line monitoring of the main Se-compound in human urine after consumption of Se-rich food was developed. Total Se-concentration in human urine after consumption of several Se-rich products was measured with inductively coupled plasma mass spectrometry (ICP-MS). The highest Se concentration in urine was observed after 4–10h. The urine samples were brought onto a reversed phase column and the Se was detected by ICP-MS. Parameters for liquid chromatography–electrospray ionization tandem mass spectrometry (LC-ESI-MS-MS) measurements were optimized by using commercially available sugars, because it is known that some of the urinary metabolites contain a sugar moiety. In order to characterize the predominant Se-metabolite, it was necessary to extensively clean-up the sample and preconcentrate the species. The main metabolite was measured on its precursor ion on three different m/z according to three isotopes of Se. Relative peak surfaces matched the relative abundances of the isotopes. The product ions could be measured in a human urine sample in accordance to the product ions of the commercially available sugars. Moreover, the evidence of a selenosugar was demonstrated by the use of the Se-isotopes when measuring the product ions. LC-ESI-MS-MS was proven to be very efficient for the characterization of the main urinary Se-metabolite and can be used for on-line monitoring of the compound in urine samples. The method can be extended for clinical screening after consumption of Se-(en)rich(ed) food by use of the Se-isotopic profile and/or of the typical product ions of (methyl)-N-acetyl-hexosamines. [Copyright &y& Elsevier]

Abstract: The application of liquid chromatography–mass spectrometry (LC–MS) was investigated for the analysis of l-5-hydroxytryptophan (5-HTP) in rat serum. The chromatographic elution was carried out using C18 column (YMC, 250mm×2mm, 5μm) with a mobile phase water: acetonitrile (93:7, v/v). Quantitative analysis was performed by negative ion mode using selective ion monitoring (SIM) method with electrospray ionization interface. The serum samples were de-proteinized with acetonitrile. The limit of detection (LOD) and limit of quantification (LOQ) in the serum was found to be 2 and 6ng and calibration curve ranging from 5 to 17ngμl−1 showed to be linear with correlation coefficient 0.994±0.0006. Within-day and day-to-day reproducibility were 0.39–0.44% and 0.66–1.67%, respectively and the recoveries of 5-HTP in the serum were 94.65–95.46%. The method developed was also found to be applicable for the analysis of Griffonia simplicifolia seed extracts and dosage forms with LOD and LOQ, 0.02 and 0.05ng, respectively and linearity range 3–20ngμl−1 with a correlation coefficient of 0.9992±0.0004. The recoveries in the extracts were 97.00–100.20% and %R.S.D. of the intra- and inter-day precision was found to be 0.27–1.29% and 0.35–1.12%. [Copyright &y& Elsevier]

Abstract: The distribution of aluminium (Al) species was investigated in the roots of Al-tolerant Chinese cabbage (Brassica rapa L. ssp. pekinensis) by employing fast protein liquid chromatography (FPLC) with inductively coupled plasma optical emission spectrometry (ICP-OES) and electrospray tandem mass spectrometry (ES–MS–MS) detection. The cabbage was exposed to a nutrient solution that contained 10μgcm−3 of Al3+. The results demonstrated that after 24h of exposure, Al was quantitatively taken up by the cabbage and was distributed in different parts of the plant. 36±6% of total Al was located in the roots, while the remaining 64±10% was transferred to the leaves. It was found that in the roots Al was partially present in the root sap (15.5%), while the majority (84.5%) was accumulated in its apoplasmic compartments. It was further demonstrated that the proportion of Al that entered the symplasm formed a complex with organic acid. Speciation analysis by FPLC with ICP-OES detection and ES–MS–MS identification of the binding ligand indicated that Al-citrate complex was the prevailing species in the root sap. The results of the present study showed that both immobilization of Al in the apoplasmic compartments of the roots and transformation of Al3+ to Al-citrate are most likely responsible for the tolerance of Chinese cabbage (B. rapa L. ssp. pekinensis) to the toxic effects of Al3+. [Copyright &y& Elsevier]

Abstract: A novel restricted-access material with cation-exchange properties was evaluated for the extraction of the peptides angiotensin 1 (Ang1) and angiotensin 2 (Ang2) from whole blood. The ion exchange diol silica (XDS) material revealed enhanced efficiency for extraction of peptides when compared with the conventional alkyl diol silica (ADS) with reversed phase extraction centers. The outer surface of XDS particles contains diol groups while the internal surface has sulphonic acid moieties with strong cation-exchange properties toward compounds with low molecular weight. This new coating for solid-phase microextraction (SPME) offers the possibility to combine all initial sample preparation steps into a single one, even for complex biological samples such as whole blood or plasma. The XDS material was immobilized on a stainless steel wire with a binding agent; the reproducibility of the procedure was determined to be 5.56%. Compounds extracted from whole blood were separated by narrow-bore liquid chromatography (LC) and Ang1 was quantified by electrospray mass spectrometry, with good linearity over the range of 25–500pM. Total analysis time was less than 90min. The detection limit for Ang1 from whole blood was determined to be 8.5pM. A single fiber could be used more than 150 times before a noticeable decrease in extraction capacity was observed. Although the limit of quantification is not as low as that of radioimmunoassay techniques, this method is much faster, less expensive and still provides enough sensitivity at physiological levels of Ang1. [Copyright &y& Elsevier]

Abstract: Electrochemically modulated liquid chromatography (EMLC) is used on-line to remove metal ions from the blank solution and improve detection limits in inductively coupled plasma-mass spectrometry (ICP-MS). The EMLC column contains glassy carbon particles held at an appropriate negative applied potential (Eapp). The supporting electrolyte and reference electrode are outside the porous stainless steel column to minimize contamination of the blank flow stream. Various metal ions, such as Tl+ and Pb2+, are retained at cathodic values of Eapp with an efficiency of 99% or better at liquid flow rates of 50–80μlmin-1. Other metals are retained at an Eapp that is moderately positive with respect to their standard reduction potentials. This latter observation suggests that surface functional groups on the carbon stationary phase are also important. The column can be cleaned easily by stripping the deposited metal at high anodic values of Eapp. [Copyright &y& Elsevier]

Abstract: The 4-(1′-cyanoisoindolyl)phenylisothiocyanate (CIPIC) could be used as a chemiluminescence (CL) Edman-type reagent. Firstly, CL reaction conditions such as pH, buffer types, H2O2 concentration and organic solvents were optimized in detail. Secondly, the CL sensitivity of the derivative of Ala was compared with fluorescence and absorbance detections. Thirdly, the structures of the CL intermediate and emitter were elucidated by liquid chromatography–mass spectrometry (LC–MS) and NMR of CIPIC and its analogues after their CL reactions. Consequently, the thiohydantoin derivatives for 16 kinds of amino acids were separated and sensitively detected by CL with lower detection limits of 0.3–0.8pmol at a signal-to-noise ratio of 3, after the coupling reaction of amino acids with CIPIC and their cyclisation reaction. [Copyright &y& Elsevier]

Abstract: We describe a method using liquid chromatography combined with positive electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) to identify the components of 16-membered macrolide antibiotics. Choosing three characteristic compounds (midecamycin A1, midecamycin acetate, 4″-isovalerylspiramycin III), the mass fragment pathway of this group of antibiotics was determined. The characteristics of these kinds of compounds on chromatographic behavior and UV spectrum were revealed and confirmed by the components in six examples (kitasamycin, midecamycin, meleumycin, josamycin, acetylspiramycin, 4″-acylspiramycin), whose structure were already known. Utilizing this method, some components that had never been reported in these samples were characterized by LC/MS. In comparison to the classical method, the LC/MS method is simple, rapid, sensitive, specific and suitable to application in the fields of multi-components antibiotics analysis. [Copyright &y& Elsevier]

Abstract: A method has been developed for the sensitive and selective determination of cyromazine and its metabolite melamine in chard samples. Both compounds are small polar basic molecules, making their determination at residue levels complicated. The method involves an extraction procedure with phosphate buffer and methanol using high-speed blender, the addition of tridecafluoroheptanoic acid (TFHA) as ion-pair reagent and the injection of the five-fold diluted extract on liquid chromatography coupled to electrospray tandem mass spectrometry (LC–ESI–MS/MS). The method has been validated for chard samples, spiked at 0.05 and 0.5mgkg-1. Quantification was carried out by using matrix-matched standards calibration and recoveries were satisfactory, with mean values for cyromazine of 103% and 93%, and relative standard deviations lower than 7%. In the case of melamine, recoveries were 89% and 86%, with relative standard deviations lower than 13%. A limit of quantification of 0.05mgkg-1 was obtained for both compounds, with the limit of detection below 0.01mgkg-1. The method, with very little sample handling and good sensitivity, was applied to the rapid determination of low residue levels of these compounds in chards from field residue trials. All the quality controls included during the analysis were satisfactory with average recoveries of 92% and 78% for cyromazine and melamine, respectively. [Copyright &y& Elsevier]

In column liquid chromatography (LC) coupled to conventional Raman spectroscopy (RS) removal of the spectral background of the eluent is often demanding, because of the strong signals of the organic modifier. A new chemometrical method is proposed, called the eluent background subtraction (EBS) method, which can correct for small shape and intensity differences of the eluent spectra. The variations in the eluent spectra are modelled using principal component analysis (PCA). The PCA loading vectors are subsequently used for eluent background correction of the elution spectra of the analyte. The loading vectors are fitted under these spectra by an asymmetric least-squares method. This method was successfully applied under various experimental conditions and performed much better than conventional background correction methods. Analyte detectability was improved by (weighted) averaging of all elution spectra and smoothing via a p-spline function. [Copyright &y& Elsevier]

Recent reports from the Brazilian Agricultural Ministry program of residue control describe some cases of the presence of semicarbazide, the target metabolite of nitrofurazone {2-[(5-nitro-2-furanyl)methylene]-hydrazinecarboxamide}, in samples of salted chicken meat. Since that contamination can be originated from other reasons in addition to nitrofurazone abuse, our laboratory has developed a sensitive and simple method for detection of four nitrofuran metabolites in salt samples. This method include a previous hexane extraction of the metabolites followed by a derivatization reaction with 2-nitrobenzaldehyde. The nitrophenyl derivatives were analyzed by liquid chromatography–tandem mass spectrometry without any additional clean-up procedures. The limit of quantification for routine analysis was 0.5 μg kg-1 for each metabolite. [Copyright &y& Elsevier]