Gas Chromatography-tandem Mass Spectrometry Analysis Research Articles

Association of HLA-DPB1, NLRP10, OVOL1, and ABCC11 with the axillary microbiome in a Japanese population

BackgroundThe distinct diversity of the human skin microbiome depends not only on the body site but also the individual. Host-commensal interactions have been described for the gut microbiome, but little is known about the epidermal microbiome. ObjectiveThe present study investigated whether genetic variants associated with skin traits affect the axillary microbiome. MethodsEight skin trait-related single nucleotide polymorphisms and HLA-A, -B, -C, and –DPB1 were genotyped in 186 Japanese males. From axillary swabs, the intensity of a representative axillary odor, trans (E) isomer of 3-methyl-2-hexenoic acid (E3M2H), was quantified with gas chromatography-tandem mass spectrometry analysis, the diversity of the axillary microbiome was evaluated with a 16 s rRNA metagenomic approach, and the association of these characteristics was assessed statistically. ResultsA risk allele for atopic dermatitis of rs878860 in NLRP10 and the allele for wet earwax of rs17822931 in ABCC11 decreased the relative abundance of Corynebacterium. Conversely, these alleles increased the relative abundance of Staphylococcus. Metagenomic analysis revealed that β-diversity showed significant dissimilarity at the weighted Unifrac distance between minor allele carrier and non-carrier groups in HLA‐DPB1*05:01, rs17822931, and rs878860. HLA‐DPB1*04:01, HLA‐DPB1*05:01, and rs17822931 were associated with E3M2H. ConclusionsWe identified novel candidate loci associated with the axillary microbiome and malodor.

9,10-Anthraquinone contamination in tea processing using coal as heat source

9,10-Anthraquinone (AQ) is a contaminant with a potential carcinogenic risk and occurs in tea worldwide. The maximum residue limit (MRL) of AQ in tea set by the European Union (EU) is 0.02 mg/kg. The possible sources of AQ in tea processing and the main stages of its occurrence were investigated based on a modified AQ analytical method and gas chromatography-tandem mass spectrometry (GC-MS/MS) analysis. Compared with electricity as the heat source in green tea processing, AQ increased by 4.3 to 23.9 times in tea processing with coal as the heat source, far exceeding 0.02 mg/kg, while the AQ level in the environment tripled. The same trend was observed in oolong tea processing under coal heat. The steps with direct contact between tea leaves and fumes, such as fixation and drying, are considered as the main steps of AQ production in tea processing. The levels of AQ increased with the rising contact time, suggesting that high levels of AQ pollutant in tea may be derived from the fumes caused by coal and combustion. Fourty samples from different workshops with electricity or coal as heat sources were analyzed, ranged from 50.0%−85.0% and 5.0%−35.0% for detection and exceed rates of AQ. In addition, the maximum AQ content of 0.064 mg/kg was observed in the tea product with coal as the heat source, indicating that the high levels of AQ contamination in tea products are likely to be contributed by coal.

Bioprospection of novel synthetic monocurcuminoids: Antioxidant, antimicrobial, and in vitro cytotoxic activities

The irrational use of medications has increased the incidence of microbial infections, which are a major threat to public health. Moreover, conventional therapeutic strategies are starting to become ineffective to treat these infections. Hence, there is a need to develop and characterize novel antimicrobial compounds. Phytochemicals are emerging as a safe and accessible alternative to conventional therapeutics for treating infectious diseases. Curcumin is extracted from the dried rhizome of the spice turmeric (Curcuma longa (Zingiberaceae)). However, the bioavailability of curcumin is low owing to its lipophilic property and thus has a low therapeutic efficacy in the host. A previous study synthesized structural variants of curcumin, which are called monocurcuminoids (CNs). CNs are synthesized based on the chemical structure of curcumin with only one methyl bridge. The biological activities of four previously synthesized CNs (CN59, CN63, CN67, and CN77), curcumin, and turmeric powder were examined in this study. Gas chromatography-tandem mass spectrometry analysis of curcumin and turmeric powder revealed similar peaks, which indicated the presence of curcumin in turmeric powder. The antioxidant activity of the test compounds was evaluated using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) assays. The ABTS radical scavenging activities of the test compounds were similar to those of vitamin C. The minimum inhibitory concentration (MIC) values of the test compounds against seven microbial strains were in the range of 4.06–150 μg/mL. The MIC value was equal to minimum bactericidal concentration value for CN63 (150 μg/mL) and CN67 (120 μg/mL) against Staphylococcus aureus. The treatment combination of CN77 (8.75 or 4.37 μg/mL) and turmeric powder (9.37 or 4.68 μg/mL) exerted synergistic growth-inhibiting effects on Aeromonas hydrophila, Candida albicans, and Pseudomonas aeruginosa. Photodynamic therapy using 2X MIC of CN59 decreased the growth of Enterococcus faecalis by 4.18-fold compared to the control group and completely inhibited the growth of Escherichia coli. The results of the hemolytic assay revealed that the test compounds were not cytotoxic with half-maximal inhibitory concentration values ranging from 49.65–130.9 μM. The anticoagulant activity of most compounds was comparable to that of warfarin but higher than that of heparin. This indicated that these compounds target the intrinsic coagulation pathway. These results demonstrated that these CNs are a safe and promising alternative for curcumin.

Turning cork by-products into smart and green materials for solid-phase extraction - gas chromatography tandem mass spectrometry analysis of fungicides in water.

During stoppers production, large amounts of cork by-products (CBPs) are generated, being used as low-value material. This project aims to turn CBPs into smart, natural and sustainable materials (sorbent) for solid-phase extraction (SPE) of pesticides from water. The study describes the use of CBPs for the extraction of 17 fungicides (metalaxyl, cyprodinil, tolylfluanid, procymidone, folpet, fludioxonil, myclobutanil, kresoxim methyl, iprovalicarb, benalaxyl, trifloxystrobin, fenhexamid, tebuconazole, iprodione, pyraclostrobin, azoxystrobin and dimethomorph) followed by gas chromatography-tandem mass spectrometry (GC-MS/MS) analysis. The most critical parameters affecting SPE were optimized by experimental design methodology. Under the optimal conditions, the method was successfully validated in terms of linearity, repeatability, and intermediate precision. Fungicide recovery was assessed in different real water samples including river, fountain, rainwater and spring water at 3 concentration levels (0.1, 0.5 and 10 µg L-1). Recoveries ranged between 70-118% with RSD values lower than 20%, and matrix effects were not observed. Finally, the method was applied to samples from irrigation, rain, and river water, all collected in vineyards areas, revealing the presence of 10 of the 17 fungicides, at concentration up to hundreds of µg L-1. The use of CBPs seems to be a promising low-cost and ecofriendly alternative to be employed as sorbent in SPE techniques to extract fungicides from the aquatic environment.

Atmospheric pressure gas chromatography-tandem mass spectrometry analysis of fourteen emerging polycyclic aromatic sulfur heterocycles in PM2.5

Research on pollution characteristics and toxicities of emerging polycyclic aromatic sulfur heterocycles (PASHs) in PM2.5 has not been reported due to the lack of analytical method with the needed performance. In the present study, a novel method for the determination of 14 PASHs in PM2.5 was developed using atmospheric pressure gas chromatography-tandem mass spectrometry (APGC-MS/MS). Atmospheric pressure chemical ionization was operated with multiple reaction monitoring in positive ionization mode. High sensitivity (method detection limit < 1.673 pg/m3), acceptable recoveries (67.6%–120.8%) and precisions (RSD of 2.2%–15.4%) were obtained. The method was successfully applied for analyzing PASHs in 10 PM2.5 samples collected from Taiyuan, a typical industrial city in China, in 2016. The total concentrations were from 929 pg/m3 to 14,593 pg/m3. The determined levels indicated that further investigations on environmental fate and toxicities of PM2.5-bound PASHs may be needed.

Pesticide residues determination in common bean using an optimized QuEChERS approach followed by solvent exchange and GC-MS/MS analysis.

Common bean is a staple food in Latin America and Africa; however, studies about contamination of common bean with pesticides are rarely reported. So, the goals of this study were to validate a multiresidue method and apply it in monitoring of pesticides in common beans. Extraction was performed applying the QuEChERS (quick, easy, cheap, effective, rugged, and safe) approach to ground samples. Octadecylsilane and primary-secondary amine were used for clean-up, and a solvent exchange step was performed before injection for gas chromatography-tandem mass spectrometry analysis. Method validation was done analyzing blank samples spiked at 20, 30, 50, and 100 μg kg-1 (n = 5). Linearity and linear range were assessed by the analysis of standard solutions at concentrations of 5, 15, 25, 50, 75, 100, and 150 μg L-1 . The method was successfully validated for 91 (64.1%) of the 142 compounds studied (139 pesticides and three degradation products). Limits of quantification were equal to 20 μg kg-1 , 30 μg kg-1 , 50 μg kg-1 , and 100 μg kg-1 for 18 (12.7%), 17 (12.0%), 21 (14.8%) and 35 (24.6%) compounds respectively. Fifteen (10.6%) compounds were not detected at any level, and 36 (25.4%) did not fulfill the requirements for a quantitative method. Sixteen common bean samples of South of Brazil were analyzed. Two samples were positive: one for tebuconzole and a second for picoxystrobin, permethrin, and cyproconazole. Cyproconazole is not allowed for use in the common bean crop, its use being a violation. As demonstrated, the validated approach is suitable for pesticide residues determination in common bean. Results of the sample analysis show that the control of pesticide residues in common bean is necessary to ensure food safety. © 2020 Society of Chemical Industry.

Compensation of matrix effects in seed matrices followed by gas chromatography-tandem mass spectrometry analysis of pesticide residues

Despite analytical advances, matrix effects (MEs) in pesticide residue analysis by gas chromatography – tandem mass spectrometry continue to be a challenge, especially in difficult samples such as seeds. In this study, the influence of different clean-up sorbents (chitin, chitosan, Z-Sep+, EMR-Lipid) and different mixtures of primary secondary amine (PSA), C18, graphitized carbon black (GCB) and MgSO4 were investigated in terms of MEs and recoveries in four types of seeds: cress, fennel, flax, and hemp. Additionally, different volumes of water (5, 7.5 and 10 mL) were investigated for QuEChERS extraction. Under the selected conditions: the largest volume of water (10 mL) and PSA/C18/GCB/MgSO4 (50/150/50/50 mg, respectively) as clean-up sorbent yielded acceptable recoveries of 70–120% for most of the pesticides (211–225 out of 248 compounds) and the lowest MEs were between −20%>MEs>20% (27–50 compounds). The final method was validated for 248 pesticides with LOQs equal to 0.005 mg kg−1. Additionally, matrix-matched calibration was used as a practical method to compensate for MEs. Among the 21 pesticides found in 12 of the samples, chlorpyrifos (0.008–1.1 mg kg−1), tebuconazole (0.071–0.96 mg kg−1), and trifloxystrobin (0.007–0.15 mg kg−1) were most commonly determined.

Determination of newly synthesized dihydroxylated polybrominated diphenyl ethers in sea fish by gas chromatography-tandem mass spectrometry

Dihydroxylated polybrominated diphenyl ethers (diOH-PBDEs) can be natural products of marine organisms or the metabolites of PBDEs. The optimal determination method and concentration of diOH-PBDEs in seafood are unknown due to a lack of commercially available standards. In the present study, diOH-PBDEs were synthesized, and an efficient measurement method for OH-PBDEs and diOH-PBDEs in sea fish muscle samples, including extraction, clean-up and gas chromatography-tandem mass spectrometry (GC-MS/MS) analysis, was established. Pressurized liquid extraction (PLE) followed by partitioning with a KOH solution and florisil cartridge clean-up proved to be a reliable and robust method for detecting all OH-PBDEs/diOH-PBDEs. GC-MS/MS with an electron ionization (EI) source analysis was a sensitive analytical instrument for OH-PBDEs/diOH-PBDEs. The recovery using this method ranged from 19% to 101%, 28%–88% and 42%–90% for 10 ng, 20 ng and 40 ng spiking levels, respectively. The equipment detection limits (EDLs) were in the range of 0.31–2.78 pg/μL, and the limits of detection (LOD) for the method were in the range of 5.07–38.74 pg/g wet weight. Concentrations of diOH-PBDEs in the marine fish muscle samples were in the range of 32.43–1528.63 pg/g wet weight. Similar compositions of OH-PBDEs/diOH-PBDEs were found within the same family of marine fish.

Analytical methodology to screen UV-filters and synthetic musk compounds in market tomatoes

A Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) methodology followed by gas chromatography-tandem mass spectrometry (GC-MS/MS) analysis was developed to extract thirteen synthetic musk compounds (SMCs: cashmeran, celestolide, phantolide, traseolide, galaxolide, tonalide, musk ambrette, musk xylene, musk ketone, musk tibetene, musk moskene, ethylene brassylate and exaltolide) and six ultraviolet-filters (UVFs: 2-ethylhexyl 4-dimethylaminobenzoate, 3-(4′-methylbenzylidene) camphor, 2-ethylhexyl 4-methoxycinnamate, 2-ethylhexyl 2-cyano-3,3-diphenylacrylate, benzophenone and drometrizole trisiloxane) from tomatoes. The proposed methodology was optimized: 2 g of freeze-dried tomato was extracted with 4 mL of water and 10 mL of ethyl acetate, adding 6 g of MgSO4 and 1.5 g of NaCl, then a dispersive solid-phase extraction was performed using 3 g of MgSO4, 300 mg of primary-secondary amino adsorbent (PSA) and 300 mg of octadecyl-silica (C18). Validation delivered recoveries between 81 (celestolide) and 119% (musk tibetene), with relative standard deviations <10%. The instrumental limit of detection varied from 0.02 (2-ethylhexyl 4-methoxycinnamate) to 3.00 pg (exaltolide and musk xylene). Regarding the method quantification limits, it ranged between 0.4 (celestolide) and 47.9 ng g−1 dw (exaltolide). The method was applied to different varieties of tomatoes (Solanum lycopersicum), revealing UVFs and SMCs between 1 and 210 ng g−1 dw. Higher concentrations were found for benzophenone (29–210 ng g−1 dw) and galaxolide (9–53 ng g−1 dw). The risk associated to the ingestion of contaminated tomatoes has also been estimated, showing that a potential health risk is unlikely.

Optimization of multi-residue method for targeted screening and quantification of 216 harmful chemicals in plastic children’s toys by gas chromatography-tandem mass spectrometry analysis

Herein, we report a multi–residue method based on dissolution–precipitation extraction combined with gas chromatography-tandem mass spectrometry (GC–MS/MS) analysis for targeted screening and quantification of 216 harmful chemicals in plastic children’s toys. We established a spectrogram database containing the first-order mass spectra of all analytes and their second-order mass spectra at different collision energies. Good separation was attained in less than 60 min. As a simple and low–cost extraction method, dissolution–precipitation exhibited good recoveries for the analytes in the plastic samples. The matrix–matched standard curves were accurate for analyte quantification in specific plastics due to the solvent effects and matrix effects. The limits of quantification range were 0.1 mg/kg to 10 mg/kg. A wide linear range of 0.1–200 mg/kg was also observed, with r2≥0.9924. The average recoveries ranged from 63.9% to 137.6%, and the relative standard deviation (n = 6) varied from 0.6% to 13.2%. Finally, 31 ABS actual toys and 30 PVC actual toys were detected and 20 analytes with contents ranging from 0.4 mg/kg to 172 mg/kg and 30 analytes from 0.8 mg/kg to 141,030 mg/kg were discovered respectively.

Detection of 11-nor-9-carboxy-tetrahydrocannabinol in the hair of drug abusers by LC–MS/MS analysis

Cannabis is the second most commonly abused illicit drug after methamphetamine in South Korea. To prove cannabis consumption, 11-nor-9-carboxy-tetrahydrocannabinol (THC-COOH), the metabolite of tetrahydrocannabinol (THC), was screened for in a hair analysis. In this study, we developed a liquid chromatography–tandem mass spectrometry (LC–MS/MS) analysis method, which was used to analyze authentic hair samples in 2017. Possible contaminants on the surface of hair samples were eliminated by washing twice each with 2mL of methanol and distilled water. After adding an internal standard (THC-COOH-d3), the hair samples (about 20mg each) were digested with 1M NaOH, extracted twice with mixed organic solvents (n-hexane:ethyl acetate), and analyzed by an LC–MS/MS system. Identification and quantification of THC-COOH and THC-COOH-d3 were performed using a multiple reaction monitoring (MRM) mode at m/z 245 and 191 and m/z 248, respectively (quantifier ions are underlined). The following validation parameters were evaluated: selectivity, linearity, limit of detection (LOD), limit of quantification (LOQ), precision, accuracy, matrix effect, and recovery. The LOD and LOQ of the method was 0.1pg/mg. Good linearity was achieved for THC-COOH in the range from 0.1 to 20pg/mg. The method showed an acceptable precision and accuracy, both of which were less than 15% at the three concentrations of THC-COOH (0.2, 1, and 10pg/mg). THC-COOH showed ion suppression at these three concentrations. The concentrations of THC-COOH in the authentic hair samples ranged from 0.10 to 27.30pg/mg (total 586 cases), and its concentrations were classified as low, medium, or high ranges, i.e., 0.10–0.39pg/mg, 0.39–1.99pg/mg, or 1.99–27.30pg/mg, respectively, according to statistical evaluation. This method showed the possibility of replacing the existing gas chromatography-tandem mass spectrometry (GC–MS/MS) analysis. However, further development of our LC–MS/MS method is necessary in order to meet the recommended 0.05pg/mg cut-off.

Green determination of brominated flame retardants and organochloride pollutants in fish oils by vortex assisted liquid-liquid microextraction and gas chromatography-tandem mass spectrometry

A "green", simple, and low-cost sample extraction procedure involving the use of a deep eutectic solvent (DES) in a vortex assisted liquid-liquid microextraction (VALLME) technique followed by gas chromatography-tandem mass spectrometry (GC-MS/MS) analysis was developed for the simultaneous determination of different PBDEs congeners and OCPs residues in fish oils. After evaluation of different eutectic mixtures, the extraction parameters (volume of DES, amount of oil sample and extraction time) were optimized by means of experimental design in order to maximise extraction efficiency. The developed method was validated in terms of linearity, accuracy and precision, presenting limits of detection in the low ng g−1 level. Its application in the analysis of five fish oil samples, allowed the detection of all the target analytes at levels up 21.5 ng g−1. Fish oils used in animal feed showed to be more contaminated than fish oils for human consumption.

Determination of 4-Methylimidazole in Ammonia Caramel Using Gas Chromatography–Tandem Mass Spectrometry (GC-MS/MS)

One of Maillard reaction products formed in the production of ammonia caramel is 4(5)-methylimidazole (4-MeI) classified as carcinogen. A method of 4-MeI determination based on ion-pair extraction and derivatisation with isobutyl chloroformate with subsequent gas chromatography-tandem mass spectrometry analysis was proposed. Tandem mass spectrometry was applied to reduce the influence of matrix and increase the selectivity and sensitivity of the method. Triple quadrupole GC-MS system was used for this study. The collision energies were optimized for MRM mode. The detection (LOD) and quantification limits (LOQ) of the elaborated method were 17 and 37.8 μg kg−1, respectively, repeatability was &lt;15% RSD for analyzed caramel samples, and the recovery for 4-MeI was 101%. Comparison of MS/MS with SIM detection on the same instrument proved almost 30 times lower LODs achieved by tandem mass spectrometry compared to SIM. Described method can be routinely used for monitoring 4-MeI as a quality and safety marker in the production of ammonia caramel.

Apoptotic and antiproliferative properties of 3β-hydroxy-Δ5-steroidal congeners from a partially purified column fraction of Dendronephthya gigantea against HL-60 and MCF-7 cancer cells.

Organisms belonging to the genus Dendronephthya are among a group of marine invertebrates that produce a variety of terpenoids with biofunctional properties. Many of these terpenoids have been proven effective as anticancer drugs. Here, we report the antiproliferative effect of 3β-hydroxy-Δ5-steroidal congeners against the proliferation of HL-60 human leukemia cells and MCF-7 human breast cancer cells. The sterol-rich fraction (DGEHF2-1) inhibited the growth of HL-60 and MCF-7 cells with IC50 values of 13.59±1.40 and 29.41±0.87μg ml-1 respectively. Treatment with DGEHF2-1 caused a dose-dependent increase in apoptotic body formation, DNA damage and the sub-G1 apoptotic cell population. Moreover, DGEHF2-1 downregulated the expression of Bcl-xL while upregulating Bax, caspase-9, and PARP cleavage in both HL-60 and MCF-7 cells. The steroid fraction was found to act via the mitochondria-mediated apoptosis pathway. Identification of the sterols was performed via gas chromatography-tandem mass spectrometry analysis. Studying the mechanism of the anticancer effect caused by these sterol derivatives could lead to the identification of other natural products with anticancer properties.

Occurrence and fate of benzotriazoles UV filters in a typical residential wastewater treatment plant in Harbin, China

Benzotriazoles (BTs) UV filters are widely used as ultraviolet absorbents for our daily products, which received increasing attention in the past decades. Residential wastewater treatment plant (WWTP) is both an important sink for wastewater and a key pollution source for receiving water for these chemicals. In this study, pretreatment and gas chromatography-tandem mass spectrometry analysis method were developed to determine the occurrence and fate of 9 BTs UV filters in wastewater and sludge from the WWTP with anaerobic-oxic treatment process (A/O) and biological aerated filter treatment process (BAF). Totally, 81 wastewater samples and 11 sludge samples were collected in four seasons. In wastewater, UV-326 and UV-329 were frequently detected, while the highest mean concentrations were detected for UV-234 and UV-329. The concentrations were in the range of <LOQs up to several hundred nanograms per liter. The removal efficiency of BTs UV filters was >85% in A/O process and 60–77% in BAF process except for UV-350, which was more difficult to remove with lower removal efficiencies of 33.3% for both A/O and BAF. All the target chemicals except for UV-320 were detected in sludge samples with the mean concentration ranging from 0.90 ng/g to 303.39 ng/g. There was no significant difference with concentrations and removal efficiency among different seasons. Higher detection frequency and concentration of BTs UV filters in downstream of the receiving water system indicated the contribution of effluent of the WWTP. Compared with other rivers, the lower concentrations in surface water in the Songhua River indicated light pollution status with of BTs UV filters.

Determination of oxidative hair dyes using miniaturized extraction techniques and gas chromatography-tandem mass spectrometry

Three methodologies based on miniaturized solvent extraction: vortex extraction (VE), ultrasound-assisted extraction (UAE), and matrix solid-phase dispersion (MSPD), were optimized for the gas chromatography-tandem mass spectrometry analysis of seven regulated oxidative hair dyes, including some of the most frequently used sensitizers in hair products (resorcinol, RL; 1-naphthol, 1NL), as well as their banned isomers (hydroquinone, HQ; 2-naphthol, 2NL). The use of MS/MS in combination with GC is a valuable approach that had not been applied before in the analysis of the considered compounds in hair dyes formulations. Parameters influencing the extraction efficiency were optimized for the three sample preparation techniques employing real sample. 0.1g of sample and 1mL of organic solvent were used in all cases, which reduced the solvent consumption compared to other methods proposed in literature. Under the optimal selected conditions, three methods were validated. Good linearity (R2≥0.991, %RSD≤10) was achieved in a broad range of concentrations. In general, quantitative recoveries were obtained in real samples spiked at low, medium and high concentration levels using the three extraction techniques (ranged from 71.4 to 118% with exceptions). Good method precision (%RSD≤14) and LOQ≤0.13μgg−1 were achieved in all cases. Results demonstrated that the three methods could be implemented indistinctly. In the commercial hair dye formulations analyzed, all investigated compounds but 2-naphtol were found. Thus, hydroquinone, one of the banned hair dyes according to EU Cosmetic Directive, was evidenced in at least one formulation.

Development of a MAb-based immunoassay for the simultaneous determination of O,O-diethyl and O,O-dimethyl organophosphorus pesticides in vegetable and fruit samples pretreated with QuEChERS

To develop a broad-specificity immunoassay for organophosphorus pesticides (OPs), a broad-specificity monoclonal antibody (MAb) for OPs against a generic hapten, O,O-diethyl O-(3-carboxyphenyl) phosphorothioate with the carboxy group in the meta position of the benzene ring, was produced. Eight haptens were prepared and covalently attached to ovalbumin (OVA) for use as coating antigens, and the optimum coating antigen was selected. Then, a sensitive and broadly class selective competitive indirect enzyme-linked immunosorbent assay (ciELISA) based on the MAb and the optimum coating antigen (hapten H-OVA, possessing an O,O-dimethyl generic structure and linked through a linear spacer arm) was developed and optimized. The MAb developed in this study showed quite different cross-reactivity and selectivity compared to previously produced anti-OPs broad-specificity MAbs. Specifically, the MAb showed high and uniform sensitivity to seven O,O-diethyl OPs and six O,O-dimethyl OPs. With the optimum ciELISA, the IC50 values of the 13 OPs were determined as 23.1∼151.2 ng mL(-1). The average IC50 and coefficient of variation (CV) for the IC50 values of the 13 OPs were 74.6 ng mL(-1) and 33.9%, respectively. For the recovery study, a QuEChERS approach based on dispersive solid-phase extraction (d-SPE) was implemented to decrease the matrix effects of vegetable and fruit samples. The recoveries of six representative OPs from the spiked samples ranged from 89.4 to 135.5%; the CV ranged from 3.5 to 15.7%. The ciELISA was also applied to real samples, followed by confirmation with gas chromatography-tandem mass spectrometry (GC-MS/MS) analysis. The results demonstrated that the ciELISA is suitable for monitoring OP contamination in vegetable and fruit samples.

Determination of Urinary PAH Metabolites Using DLLME Hyphenated to Injector Port Silylation and GC-MS-MS.

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental pollutants and well-known carcinogens. Hydroxy derivatives of PAH are considered as biomarkers of PAH exposure, and there is a need to measure these metabolites at low concentrations. So, a precise and eco-friendly analytical method has been developed for rapid determination of PAH metabolites. For the first time, a new analytical method based on coupling of dispersive liquid-liquid microextraction (DLLME) with auto-injector port silylation (auto-IPS) followed by gas chromatography-tandem mass spectrometry (GC-MS-MS) analysis is reported for the analysis of seven urinary PAH metabolites. Factors affecting DLLME and IPS, such as type and volume of extraction and disperser solvent, pH, ionic strength, injector port temperature, volume of N,O-bis(trimethylsilyl)trifluoroacetamide and type of solvent were investigated. Under optimized conditions, the limit of detection and limit of quantification were found to be in the range of 1-9 and 3-29 ng/mL, respectively. Satisfactory recoveries of metabolites in urine samples in the range of 87-95% were found. The developed method has been successfully applied for the determination of PAH metabolites in urine samples of exposed workers. DLLME-auto-IPS-GC-MS-MS method is time, labor, solvent and reagent saving, which can be routinely used for the analysis of urinary PAH metabolites.

Unstable simple volatiles and gas chromatography-tandem mass spectrometry analysis of essential oil from the roots bark of Oplopanax horridus extracted by supercritical fluid extraction.

Volatile oil from the root bark of Oplopanax horridus is regarded to be responsible for the clinical uses of the title plant as a respiratory stimulant and expectorant. Therefore, a supercritical fluid extraction method was first employed to extract the volatile oil from the roots bark of O. horridus, which was subsequently analyzed by GC/MS. Forty-eight volatile compounds were identified by GC/MS analysis, including (S,E)-nerolidol (52.5%), τ-cadinol (21.6%) and S-falcarinol (3.6%). Accordingly, the volatile oil (100 g) was subjected to chromatographic separation and purification. As a result, the three compounds, (E)-nerolidol (2 g), τ-cadinol (62 mg) and S-falcarinol (21 mg), were isolated and purified from the volatile oil, the structures of which were unambiguously elucidated by detailed spectroscopic analysis including 1D- and 2D-NMR techniques.

A multiclass method for the analysis of endocrine disrupting chemicals in human urine samples. Sample treatment by dispersive liquid–liquid microextraction

The population is continuously exposed to endocrine disrupting chemicals (EDCs). This has influenced an increase in diseases and syndromes that are more frequent nowadays. Therefore, it is necessary to develop new analytical procedures to evaluate the exposure with the ultimate objective of establishing, in an accurate way, relationships between EDCs and harmful health effects. In the present work, a new method based on a sample treatment by dispersive liquid–liquid microextraction (DLLME) for the extraction of six parabens (methyl-, ethyl-, isopropyl-, propyl-, isobutyl and butylparaben), six benzophenones (benzophenone-1, benzophenone-2, benzophenone-3, benzophenone-6, benzophenone-8 and 4-hydroxybenzophenone) and two bisphenols (bisphenol A and bisphenol S) in human urine samples, followed by gas chromatography-tandem mass spectrometry (GC–MS/MS) analysis is proposed. An enzymatic treatment allows determining the total content of the target EDCs. The extraction parameters were accurately optimized using multivariate optimization strategies. Ethylparaben ring-13C6 and bisphenol A-d16 were used as surrogates. Found limits of quantification ranging from 0.2 to 0.5ngmL−1 and inter-day variability (evaluated as relative standard deviation) ranging from 2.0% to 14.9%. The method was validated using matrix-matched standard calibration followed by a recovery assay with spiked samples. Recovery rates ranged from 94% to 105%. A good linearity, for concentrations up to 300ngmL−1 for parabens and 40ngmL−1 for benzophenones and bisphenols, respectively, was obtained. The method was satisfactorily applied for the determination of target compounds in human urine samples from 20 randomly selected individuals.