Ultra-performance Liquid Chromatography-electrospray Tandem Mass Research Articles

Effect of Mobile Phase pH on the Electrospray Ionization Efficiency and Qualitative Analysis of Pharmaceuticals in ESI+LC-MS/MS.

The effect of mobile phase pH on positive ionization process and retention time of nine pharmaceuticals on ultra-performance liquid chromatography-electrospray-tandem mass spectrometry (LC-MS/MS) was discussed. The effective use of high and low mobile phase pH in LC-MS/MS qualitative analyses method was also evaluated by comparing the instrument detection limit, quantification limit, precision, linearity and signal to noise (S/N) under low and high mobile phase pH. In this work, six mobile phase pH that ranged between pH2 and pH10 were used to evaluate the effect of the mobile phase pH changes on the ionization process in electrospray ionization. Results revealed that high mobile phase pH ionized more pharmaceuticals molecules and gave a higher signal than low mobile phase pH in positive ionization mode. The results proved that ammonium ion was better as a proton donor in high pH mobile phase than the hydronium ion in acidic mobile phase. The results revealed that the qualitative LC-MS/MS analyses method by using high mobile phase pH has better performance for most analytes in terms of sensitivity, precision, linearity and S/N than the low mobile phase pH.

Highly sensitive analytical method for herbicide clopyralid residue in cattle manure compost with ultraperformance liquid chromatography tandem mass spectrometry.

A micro liquid-liquid extraction has been applied to sample preparation in the current authorized method for clopyralid in compost. The method rendered matrix effects practically negligible during determination with ultraperformance liquid chromatography-electrospray ionization tandem mass spectrometry with an improved limit of quantification of 0.7 µg/kg dry weight. Moreover, it had good accuracy and reproducibility. Therefore, the method is proposed as a highly effective routine analytical technique for investigating the actual status of clopyralid residue in compost.

Abstract P3-11-16: Immunosuppressive profiles in liquid biopsy predict response to neoadjuvant chemotherapy in triple negative breast cancer

Abstract BACKGROUND Despite the recent advances in triple negative breast cancer (TNBC) stratification, TNBC is still a highly heterogeneous subtype that clusters distinct molecular and genetic alterations with diverse responses to neoadjuvant chemotherapy (NAC). Molecular profiling after NAC has unraveled a group of actionable targets in residual TNBC that supports the implementation of targeted therapies in a personalized manner. However, unresponsive or poor NAC responders after first line treatment are committed to poorer outcome. Therefore, early identification of poor NAC responders is essential to select patients that may benefit from alternative therapies, including initial tumor resection before chemotherapy. MATERIAL AND METHODS We have conducted a study on 37 non-metastatic TNBC patients at La Fe Hospital that were homogeneously treated with anthracycline and cyclophosphamide followed by paclitaxel. Tissue and blood-derived biopsies were obtained at diagnosis. Metabolites and miRNA exosomes in plasma were analyzed by ultra-performance liquid chromatography-electrospray ionization tandem mass spectrometric and by miRNA 3.0 arrays (Affymetrix) respectively. Immunosuppressive subpopulations of cells were quantified by flow cytometry with specific markers. IDO1 in situ expression was assessed by immunohistochemistry on the tissue biopsies. RESULTS In order to identify blood-derived liquid biopsy NAC predictor biomarkers in TNBC we have studied blood circulating cells and molecules known for their immunomodulation capacity and found that eMDSC and a profile of tryptophan-derived metabolites predict NAC response. In addition, we identified a circulating exosome miRNA profile that identifies poor NAC responders. Interestingly, this profile of miRNAs target pathways involved in the immune response. IDO1 expression in the tumor inversely correlated with circulating tryptophan levels and directly associated with eMDSC. We also observed a trend correlating IDO1 expression levels with poorer response. CONCLUSIONS Our results strongly support the role of immunosuppression in TNBC poor responders and establish an easy and non-invasive tool for the early identification of poor NAC responders, opening the possibility to use alternative strategies. Acknowledgements: The authors would like to thank the Cytomics Unit, Instituto de Investigación Sanitaria La Fe (IIS La Fe), Valencia, Spain for its technical support. This work was partially financed with FEDER funds (CIBERONC (CB16/ 12/00284)) and AMACMA breast cancer association. Citation Format: Salvador-Coloma C, Font De Mora J, Cordón L, Palomar L, Santaballa A. Immunosuppressive profiles in liquid biopsy predict response to neoadjuvant chemotherapy in triple negative breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P3-11-16.

Development and validation of an LC–MS/MS method for the simultaneous determination of citrinin and ochratoxin a in a variety of feed and foodstuffs

An ultra-performance liquid chromatography-electrospray tandem mass spectrometry (UPLC-ESI+/−-MS/MS) method for the simultaneous analysis of citrinin (CIT) and ochratoxin A (OTA) in feed (chicken and pig) and food (cereal-based products, fruit, vegetable juices, nuts, seeds, herbs, spices, vegetarian and soy products, alcoholic beverages, baby food products and food supplements) was developed. The mycotoxins were extracted from these matrices using a QuEChERS-based extraction method without any further clean-up step. The samples were 5-fold concentrated. Final extracts were analyzed using a UPLC–MS/MS system and chromatographic separation was achieved by applying a gradient elution for a total run time of 10 min. Mycotoxins were quantified using an internal calibration via analyte/13C-labeled internal standard ratio. The developed method was validated according to the criteria described in Commission Regulation No. 401/2006/EC and Commission Decision No. 2002/657/EC. Specificity, linearity, apparent recovery, limit of detection and quantification, intraday and interday precision, measurement uncertainty, matrix effect, and extraction efficiency were the parameters studied. Finally, 90 Belgian chicken and pig feed samples were analyzed, revealing the simultaneous presence of CIT (<LOQ − 3.90 μg/kg) and OTA (<LOQ − 5.60 μg/kg) in more than 50% of these products.

Pharmacokinetics and Bioavailability Study of Monocrotaline in Mouse Blood by Ultra-Performance Liquid Chromatography-Tandem Mass Spectrometry.

Background and Aims The present study aimed to develop a simple and sensitive method for quantitative determination of monocrotaline (MCT) in mouse blood employing ultra-performance liquid chromatography-electrospray ionization tandem mass spectrometry (UPLC-ESI/MS/MS) using rhynchophylline as an internal standard. Methods Proteins present in the blood samples were precipitated using acetonitrile. MCT was separated using a 1.7-μm ethylene bridged hybrid (BEH) C18 column (2.1 mm × 50 mm) with a gradient elution program and a constant flow rate of 0.4 mL/min. The LC mobile phase consisted of 10 mmol/L ammonium acetate (containing 0.1% formic acid) and acetonitrile. The total elution time was 4.0 min. The analytes were detected on a UPLC-ESI mass spectrometer in multiple reaction monitoring (MRM) mode and quantified. Results The new method for the determination of MCT has a satisfactory linear detection range of 1-2000 ng/mL and excellent linearity (r = 0.9971). The lower limit of quantification (LLOQ) of MCT is 1.0 ng/mL. Intra- and interassay precisions of MCT were ≤13% with an accuracy from 96.2% to 106.6%. The average recovery of the new method was >75.0%, and matrix effects were between 89.0% and 94.3%. Based on the pharmacokinetics data, the bioavailability of MCT in mice was 88.3% after oral administration. Conclusions The results suggest that the newly standardized method for quantitative determination of MCT in whole blood is fast, reliable, specific, sensitive, and suitable for pharmacokinetic studies of MCT after intravenous or intragastric administration.

Sensitive analysis of steroid estrogens and bisphenol a in small volumes of water using isotope-dilution ultra-performance liquid chromatography-tandem mass spectrometry.

An isotope-dilution ultra-performance liquid chromatography-electrospray tandem mass spectrometry method combined with dansylation was established to sensitively quantify four steroid estrogens (estrone, 17α-estradiol, 17β-estradiol and 17α-ethynylestradiol) and bisphenol A in sewage influent and effluent. A simple hexane extraction was performed from a small volume (10 mL), followed by dansyl chloride derivatization and purification with a silica cartridge. The method effectively reduced the matrix effects in sample extract and permitted the selective and sensitive determination of target compounds from complicated matrices. The detection limits of the method for steroid estrogens were 0.20-0.90 ng L-1 in influent and 0.10-0.20 ng L-1 in effluent samples. For bisphenol A, the limits detection of the method were 20 and 0.80 for influent and effluent samples, respectively. Recoveries of 85%-96% were observed in all matrices. The method was applied to analyze residual estrogens and bisphenol A in sewage influent and effluent samples from Beijing, China. The concentrations of bisphenol A (636-1200 ng L-1) were up to 250 times higher than those of steroid estrogens. Estrone was the dominant estrogen in influent and effluent samples, while similar concentrations of 17α-estradiol and 17β-estradiol were detected in all samples.

Pharmacokinetic Study of Sirolimus-Eluting BioResorbable Vascular Scaffold System for Treatment of De Novo Native Coronary Lesions: A Sub-Study of MeRes-1 Trial.

BackgroundMeRes100™ (Meril Life Sciences Pvt. Ltd., Vapi, India) is a novel sirolimus-eluting bioresorbable vascular scaffold (BRS). The purpose of this sub-study of MeRes-1 trial is to evaluate the systemic release of sirolimus from MeRes100 BRS implanted for the treatment of de novo native coronary artery lesions.MethodsThe MeRes-1 is a prospective, multicenter, first-in-human trial of sirolimus-eluting MeRes100 BRS. The pharmacokinetic sub-study was conducted at two Indian sites in 10 patients who were implanted with the MeRes100 BRS loaded with sirolimus at a dose of 1.25 µg/mm2. Venous blood samples were collected at pre-dose and 12-time points after implantation of the scaffold. Sirolimus concentration was successively analyzed using ultra-performance liquid chromatography-electrospray ionization tandem mass spectrometry method.ResultsA total of 12 scaffolds were implanted in 10 patients. Non-compartmental analysis demonstrated time to reach peak concentration of sirolimus between 0.5 h to 3 h after scaffold implantation. The peak concentration (Cmax) was deduced to be 7.47 ± 2.61 ng/mL, AUC was 436.45 ± 171.24 h·ng/mL, and the t½ was observed at 98.59 ± 33.58 h. The clearance was 0.66 ± 0.16 L/h and lower limit of quantification was detectable at 14.1 days.ConclusionsThe MeRes-1 pharmacokinetic sub-study confirmed that MeRes100 BRS is safe and tolerable at limited systemic exposure of sirolimus.

Quantitative Analysis of Amoxicillin, Amoxicillin Major Metabolites, and Ampicillin in Chicken Tissues via Ultra-Performance Liquid Chromatography-Electrospray Ionization Tandem Mass Spectrometry

This manuscript describes a rapid, sensitive, and specific approach that utilizes ultra-performance liquid chromatography-electrospray ionization tandem triple quadrupole mass spectrometry (UPLC-ESI/MS/MS) for the selective determination of amoxicillin, amoxicillin metabolites, and ampicillin in chicken tissue samples (muscle, liver, and kidney). This optimized method was validated according to the requirements defined by the European Union and the Food and Drug Administration. The extract obtained after extraction and purification of chicken tissues was injected into a UPLC system coupled to a mass spectrometer operated in the positive electrospray MS/MS mode for analysis. The chicken tissues were spiked with the target compounds at levels of 25.0, 50.0, and 100.0 μg/kg, and the results showed that the extraction recoveries were all higher than 84% and the relative standard deviations did not exceed 20%. The limits of detection and limits of quantification were 0.01–1.36 and 0.05–5.44 μg/kg, respectively. The decision limits were 52.62–57.26 μg/kg, and the detection capabilities were 55.23–64.51 μg/kg. Finally, the new approach was verified through quantitative determination of the analytes in tissues from 30 commercial chickens obtained from local supermarkets.

Quantification of Piperazine in Chicken Muscle by Ultra-Performance Liquid Chromatography-Electrospray Ionization Tandem Mass Spectrometry

An ultra-performance liquid chromatography-electrospray ionization tandem triple quadrupole mass spectrometry (UPLC-ESI/MS/MS) method was developed for the detection of piperazine in chicken muscle. Following extraction and purification, the chicken muscle extract was injected into the UPLC system and analyzed. Piperazine detection was performed on a triple-quadrupole mass spectrometer with the ESI interface operating in positive mode. The most sensitive mass transition from the precursor ion to the product ion was 87.1 → 44.1 for piperazine. The coefficient (R2) of piperazine was 0.9995 in the range of 1–200 μg/kg. The recovery and relative standard deviation (RSD) ranged from 102.93 to 111.46% and from 4.57 to 5.28% at 50.0, 100.0 and 200.0 μg/kg adding levels, respectively. Limits of detection (LODs) and limits of quantification (LOQs) were 0.4 and 1.0 μg/kg, respectively. This method was fully validated based on its specificity, sensitivity, linearity, precision, accuracy, matrix effect, and stability results. Compared to other researches, this new method not only omitted the derivative process, which simplify the pre-processing, but also proved a better sensitivity based on its low LOD and LOQ values.

Bioaccessibility of individual phenolic compounds in extra virgin argan oil after simulated gastrointestinal process

The bioaccessibility of individual phenolic compounds in extra virgin argan oil was evaluated using an in vitro digestion method for first time. The analyses were carried out by ultra-performance liquid chromatography-electrospray ionisation tandem mass spectrometry in multiple reaction monitoring (UPLC-ESI-MS/MS). Hydroxyphenylacetic acid (4245 μg/kg), ferulic acid (2478 μg/kg), vanillin (2429 μg/kg) and 3,4-dihydroxybenzoic acid (2247 μg/kg) were the mayor compounds identified in argan oil extracts. After the digestion process, values of bioaccessibility of the different compounds varied from a minimum of 2% (hydroxyphenylacetic acid) to a maximum of 84% (p-coumaric acid), but some such as caffeic acid became detectable, as a result from digestive transformations. The results indicate that the phenolic compounds of the argan oil are strongly affected during the digestive process, and bioaccessibility should be taken into account when assessing polyphenol content of oils.

Profiling of phytohormones in rice under elevated cadmium concentration levels by magnetic solid-phase extraction coupled with liquid chromatography tandem mass spectrometry

Phytohormones, a collection of signal small molecules with various structures, regulate a series of physiological processes of plants. For instance, they regulate the growth and development, response to biotic and abiotic stresses. Quantification of trace endogenous phytohormones is essential to elucidate their molecular mechanisms in response to stresses. However, the structural and chemical diversity of phytohormones make it difficult to purify and enrich multiple phytohormones in one-step. In the current study, a method was developed to comprehensively profile phytohormones, including 8 cytokinins (CKs), indole-3-acetic acid (IAA), abscisic acid (ABA), jasmonic acid (JA) and 10 gibberellins (GAs) by Fe3O4@TiO2-based magnetic solid-phase extraction coupled with ultra-performance liquid chromatography-electrospray tandem mass spectrometry (Fe3O4@TiO2-based MSPE-UPLC-MS/MS). In the proposed method, the phytohormones in the acetonitrile extract of plant tissues were captured and purified by one-step MSPE using Fe3O4@TiO2 as a sorbent prior to UPLC-MS/MS analysis. The sensitivity, accuracy and reproducibility of the proposed analytical method were demonstrated to satisfy the profiling of multiple phytohormones in plant tissue. We then further used the Fe3O4@TiO2-based MSPE-UPLC-MS/MS method to explore the change of phytohormones in rice under Cd stress. The results showed that CKs, IAA, ABA, JA and biological active GAs all increased under Cd stress, suggesting that these phytohormones may take part in response to Cd stress. The study may promote the further understanding of the physiological functions of phytohormones in response to Cd stress.

Selective pressure of antibiotics on ARGs and bacterial communities in manure-polluted freshwater-sediment microcosms.

The aim of this study was to investigate selective pressure of antibiotics on antibiotic resistance genes (ARGs) and bacterial communities in manure-polluted aquatic environment. Three treatment groups were set up in freshwater-sediment microcosms: tetracyclines group, sulfonamides group and fluoroquinolones group. Sediment and water samples were collected on day 14 after treatment. Antibiotic concentrations, ARGs abundances and bacterial community composition were analyzed. Antibiotic concentrations were determined by ultra-performance liquid chromatography-electrospray tandem mass spectrometry. ARGs abundances were quantified by real time quantitative PCR. Bacterial community composition was analyzed based on amplicon sequencing. Of the three classes of antibiotics analyzed in the treatment groups, accumulation amounts were tetracyclines> fluoroquinolone> sulfonamides in the sediment samples, while they were sulfonamides> fluoroquinolone> tetracyclines in the water samples. In the treatment groups, the relative abundances of some tet resistance genes [tet(W) and tet(X)] and plasmid-mediated quinolone resistance (PMQR) genes [oqx(B) and aac(6′)-Ib] in sediment samples were significantly higher than those in the paired water samples. Tetracyclines significantly selected the bacterial classes including Gammaproteobacteria, Clostridia, and the genera including Salmonella, Escherichia/Shigella, Clostridium, Stenotrophomonas in sediment samples. The significant selection on bacterial communities posed by sulfonamides and fluoroquinolones was also observed. The results indicated that sediment may supply an ideal setting for maintenance and persistence of tet resistance genes [tet(W) and tet(X)] and PMQR genes [oqx(B) and aac(6′)-Ib] under antibiotic pollution. The results also highlighted that antibiotics significantly selected specific bacterial communities including the taxa associated with opportunistic pathogens.

Simultaneous analysis of N(ε) -(carboxymethyl)Lysine and N(ε) -(carboxyethyl)lysine in foods by ultra-performance liquid chromatography-mass spectrometry with derivatization by 9-fluorenylmethyl chloroformate.

Isotope dilution ultra-performance liquid chromatography-electrospray tandem mass spectrometry with derivatization by 9-fluorenylmethyl chloroformate was successfully applied to quantify N(ε) -(carboxymethyl)lysine (CML) and N(ε) -(carboxyethyl)lysine (CEL) in processed foods. We demonstrate that this analytical method is well validated for the determination of CML and CEL contents in processed foods. Relative standard deviations (RSD) indicate repeatability (RSD < 6% for CML and CEL) and reproducibility (RSD < 6% for CML and < 7% for CEL) in this method. Percent recovery is also good. We obtain recoveries of 102% to 112% for CML and 86% to 114% for CEL. CML levels detected in the samples vary from 2.29 to 480 mg/kg food, whereas CEL is detected in significantly lower concentrations ranging from 0.56 to 107 mg/kg food. These data could help consumers make better food choices by monitoring intake of advanced glycation end-products, which may pose a risk to human health.

Antibiotic resistance genes occurrence and bacterial community composition in the Liuxi River

Antibiotic resistance genes (ARGs) in the environment have paid great concern due to their health risk. We investigated antibiotics concentrations (tetracyclines, sulfonamides and fluoroquinolones), ARGs abundances (tetracycline, sulfonamide and plasmid-mediated quinolone resistance (PMQR) genes), and bacterial community composition in sediment and water samples in the Liuxi River, China. Antibiotics concentrations were determined by ultra-performance liquid chromatography-electrospray tandem mass spectrometry. ARGs abundances were quantified by a culture-independent method. Bacterial community composition was analyzed by metagenomic approach based on Ion Torrent Personal Genome Machine platform. Antibiotics concentrations were at the levels of 1.19 to 622 ug kg-1 in sediment samples and below the limit of detection to 127 ng L-1 in water samples. Relative abundances (ARGs copies/16S rRNA gene copies) of detected ARGs were at the range of 10-5 to 10-2. The dominant phyla were Proteobacteria, Bacteroidetes and Verrucomicrobia in sediment samples, and were Proteobacteria, Actinobacteria and Bacteroidetes in water samples. The results indicated that the river environment was contaminated by antibiotics and may be as a reservoir of ARGs. This study provided quantitative data on antibiotics, ARGs and bacterial community composition in the Liuxi River, a geographical location different from the reported studies.

A systematic evaluation of collagen cross-links in the human cervix

The mechanical strength of the cervix relies on the cross-linking of the tissue's collagen network. Clinically, the internal os is functionally distinct from the external os. We sought to detect specific collagen cross-links in human cervical tissue and determine whether cross-link profiles were similar at the internal and external os. Transverse slices of cervical tissue were obtained at the internal and external os from 13 nonpregnant, premenopausal women undergoing a benign hysterectomy. To understand how cross-links were distributed throughout the entire cervix and at the internal and external os, biopsies were obtained from 3 circumferential zones in 4 quadrants from each slice. Biopsies were pulverized, lyophilized, reduced with sodium borohydride, hydrolyzed with hydrochloric acid, and reconstituted in heptafluorobutyric acid buffer. Hydroxyproline was measured by ultraperformance liquid chromatography-electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS), converted to total collagen, and normalized by dry weight. Collagen cross-links pyridinoline (PYD), deoxypyridinoline (DPD), dihydroxylysinonorleucine (DHLNL), and the nonenzymatic advanced glycation end product pentosidine (PEN) were measured by UPLC-ESI-MS/MS and reported as cross-link density ratio (cross-link/total collagen). Generalized estimated equation analysis was used to compare results between the internal and external os and to compare quadrants and zones within slices from the internal and external os to determine if cross-link profiles were similar. A total of 592 samples from 13 patients were analyzed. Collagen cross-links are detectable in the human cervix by UPLC-ESI-MS/MS. When comparing all samples from the internal and external os, similar levels of collagen content, PYD, DHLNL, and DPD were found, but PEN density was higher at the external os (0.005 vs 0.004, P = .001). When comparing all internal os samples, significant heterogeneity was found in collagen content and cross-link densities across zones and quadrants. The external os exhibited heterogeneity only across zones. Collagen cross-links (PYD, DPD, DHLNL, and PEN) are detectable by UPLC-ESI-MS/MS in the human cervix. The internal os exhibits significant collagen cross-link heterogeneity compared with the external os. Further studies are needed to evaluate how collagen cross-link heterogeneity correlates to the mechanical strength and function of the human cervix.

TREE JOINTING AND BRANCH BENDING INFLUENCE ENDOGENOUS LEVELS OF HORMONES AND FLOWERING IN JAPANESE PLUM 'KIYO'

The joint tree training system was developed in Japan as a horticultural intervention to promote flower induction (FI) in fruit trees. In this system, the apical tip of one tree is artificially grafted into the bent main stem of another in a row of three or more trees. The system reportedly facilitates faster establishment of the tree framework leading to faster FI and high productivity of the orchard earlier than those utilizing traditional systems. Plant hormones are putative bio regulators of flower induction and development. However, changes in phytohormone levels as a result of this cultural intervention have not been reported. To investigate this, 5-year old trees of 'Kiyo' Japanese plum (Prunus salicina) in containers were either bent and jointed into a row of three trees (Bent-Joint group), or individually bent (Bent group). Upright individual trees served as control. Young leaves were analyzed for phytohormone content by ultra-performance liquid chromatography-electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS). Our results showed that both the Bent and Bent-Joint groups have significantly lower concentrations of the bioactive gibberellins (i.e., GA1, GA3 and GA4), but higher abscisic acid (ABA) content compared to the control. Consistent with the implicated role of GA as suppressor, and ABA as inducer of FI, both the Bent and Bent-Joint groups registered high flowering rates. Fruit-set was also observed in these groups, while the control had none. The number of new shoots did not significantly vary across treatment groups. Yet control trees, having relatively high bioactive GAs and low ABA contents, exhibited the most vigorous shoot elongation. These findings suggest that the joint tree training system appear to favor FI and fruit-set over vegetative growth that may have resulted from the observed low levels of bioactive GAs and high ABA content.

Comparison of solid phase- and liquid/liquid-extraction for the purification of hair extract prior to multi-class pesticides analysis

The present study focuses on the influence of a purification step - after extraction of pesticides from hair and before analysis of the extract - on the sensitivity of analytical methods including compounds from different chemical classes (both parent and metabolites). Sixty-seven pesticides and metabolites from different chemical classes were tested here: organochlorines, organophosphates, carbamates, pyrethroids, ureas, azoles, phenylpyrazoles and neonicotinoids. Two gas chromatography-negative chemical ionization-tandem mass spectrometry methods and one based on ultra-performance liquid chromatography-electrospray tandem mass spectrometry were used. Seven solid-phase extraction cartridges: C18, S-DVB, PS-DVB, GCB, GCB/PSA, SAX/PSA and Florisil/PSA were tested and compared to more classical liquid-liquid extraction procedures using ethyl acetate, hexane and dichloromethane. Although LLE allowed obtaining good results for some compounds, on the whole, SPE clearly provided better recovery for the majority of the pesticide residues tested in the present study. GCB/PSA was clearly the best suited to non-polar compounds such as organochlorines, pyrethroids and organophosphates, with recovery ranging from 45.9% (diflufenican) to 117.1% (parathion methyl). For hydrophilic metabolites (e.g. dialkyl phosphates and other organophosphate metabolites, pyrethroid metabolites, phenols and carbamate metabolites), the best results were obtained with PS-DVB, with recovery ranged from 10.3% (malathion monocarboxylic acid) to 93.1% (para-nitrophenol). For hydrophilic parent pesticides (e.g. neonicotinoids, carbamates, azoles) and metabolites without nucleophilic functions, the best recovery was obtained with SAX/PSA, with recovery ranging from 52.1% (3-hydroxycarbofuran) to 100.9% (3,4-dichloroaniline). Solid phase extraction was found to be more suitable than the liquid-liquid extraction for pesticides and their metabolites determination in terms of number of extracted compounds and their recovery. Moreover, the use of solid phase extraction cartridges has enabled the reduction of the analytical background noise, resulting in better chromatographic separations.

Simultaneous determination of eight additives in polymer food packaging materials by ultra-performance liquid chromatography-electrospray ionization tandem mass spectrometry

An ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was proposed for the simultaneous determination of eight additives (Irgafos 168 (tri(2.4-di-tert-butylphenyl)phosphite), Irganox 1076 (octadecyl-β-(4-hydroxy-3, 5-di-tert-butylphenyl)propionate), Irganox 1010 (pentaerythritol tetrakys 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate), BHA (butyl hydroxy anisole), TBHQ (tertiary butylhydroquinone), PG (propyl gallate), DG (dodecyl gallate), UV-326 (2-( 2'-hydroxyl-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole) in food packaging materials. After extracted by chloromethane through ultrasonic extraction, the samples were analyzed by UPLC-MS/MS. The chromatographic conditions were optimized, and the best separation was obtained on a Waters BEH-C18 column (50 mm x 2. 1 mm, 1.7 μm) with gradient elution of 0. 05% acetic acid solu- tion and methanol. The analysis was performed by UPLC-MS/MS with electrospray ionization (ESI) source in switching between the positive and negative ion modes in one run for multiple reaction monitoring. The eight additives showed good linear relationships in the ranges with all the correlation coefficients (R2) more than 0. 993. The limits of detection (LODs, S/N= 3) and limits of quantitation (LOQs, S/N= 10) of this method were 0. 13-5.50 μg/L and 0.45-17.50 μg/L, respectively. The recoveries were in the range of 63. 9% - 127. 0% with all the RSDs < 15. 8% (n= 6). This method is simple, accurate and effective for the analysis of the eight additives in food packaging materials.

Traffic-related air pollution. A pilot exposure assessment in Beirut, Lebanon

Traffic-related volatile organic compounds (VOCs) pollution has frequently been demonstrated to be a serious problem in the developing countries. Benzene and 1,3-butadiene (BD) have been classified as a human carcinogen based on evidence for an increased genotoxic and epigenotoxic effects in both occupational exposure assessment and in vivo/in vitro studies. We have undertaken a biomonitoring of 25 traffic policemen and 23 office policemen in Beirut, through personal air monitoring, assessed by diffusive samplers, as well as through the use of biomarkers of exposure to benzene and BD. Personal benzene, toluene, ethylbenzene, and xylene (BTEX) exposure were quantified by GC–MS/MS, urinary trans, trans-muconic acid (t,t-MA) by HPLC/UV, S-phenyl mercapturic acid (S-PMA), monohydroxy-butenyl mercapturic acid (MHBMA) and dihydroxybutyl mercapturic acid (DHBMA) by ultra-performance liquid chromatography-electrospray tandem mass spectrometry (UPLC/ESI(-)-MS/MS) in MRM (Multiple Reaction Monitoring) mode. We found that individual exposure to benzene in the traffic policemen was higher than that measured in traffic policemen in Prague, in Bologna, in Ioannina and in Bangkok. t,t-MA levels could distinguish between office and traffic policemen. However, median MHBMA levels in traffic policemen were slightly elevated, though not significantly higher than in office policemen. Alternatively, DHBMA concentrations could significantly distinguish between office and traffic policemen and showed a better correlation with personal total BTEX exposure. DHMBA, measured in the post-shift urine samples, correlated with both pre-shift MHMBA and pre-shift DHMBA. Moreover, there was not a marked effect of smoking habits on DHBMA. Taken together, these findings suggested that DHBMA is more suitable than MHBMA as biomarker of exposure to BD in humans. Traffic policemen, who are exposed to benzene and BD at the roadside in central Beirut, are potentially at a higher risk for development of diseases such as cancer than office policemen.

Comparative Pharmacokinetics Study after Oral Administration of Geniposide in Normal Rats and Adjuvant‐induced Arthritis Rats by UPLC‐MS/MS

A simple and rapid ultra-performance liquid chromatography-electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS) method for quantitative analysis of geniposide (GE) in rat plasma was developed, validated and applied to determine the level of GE in rat plasma after oral administration of GE in adjuvant-induced arthritis (AA) and normal rats. The investigation showed that there were significant differences in the groups between the normal rat and AA rat in pharmacokinetics parameters, such as the area under the time versus drug concentration curve (AUC(0-∞)) (3.77 ± 0.68 versus 2.27 ± 0.42, p < 0.05), the apparent volume of distribution (V) (140.41 ± 2.07 versus 136.51 ± 1.03, p < 0.05), the mean residence time (MRT) (3.98 ± 0.90 versus 3.80 ± 0.50, p < 0.05) and the clearance from the total body (CL) (16.10 ± 2.87 versus 26.44 ± 4.94, p < 0.05). The results indicated that AA could alter the pharmacokinetics of the drug and these experimental findings could be useful for the further study of the clinical applications of GE.