Gas Chromatography-tandem Mass Spectrometry Research Articles

France-Wide Monitoring of 1,4-Dioxane in Raw and Treated Water: Occurrence and Exposure Via Drinking Water Consumption.

In recent years, 1,4-dioxane has emerged as a pollutant of increasing concern following widespread detection in the aquatic environment of several countries. This persistent contaminant with specific physical and chemical properties can be rapidly dispersed and transported to river banks, groundwater and drinking water. Given the limited data on its occurrence in France, it was considered necessary to assess the potential exposure of the French population to this compound in drinking water. An analytical method based on solid-phase extraction (SPE) combined with gas chromatography tandem mass spectrometry (GC-MS/MS) was developed and validated during this study with a limit of quantification (LOQ) of 0.15µg/L. Recoveries in natural water matrices ranged from 113 to 117% with a relative bias not exceeding 17%. This method was used for a nationwide campaign at almost 300 sites, evenly distributed over 101 French départements (administrative units), including some that were overseas. Of the 587 samples analysed, only 8% had a concentration that was greater than or equal to the LOQ. 1,4-Dioxane was detected mainly (63%) in raw and treated water from sites associated with historical industrial practices related to the use of chlorinated solvents. Concentrations of 1,4-dioxane ranging from 0.19 to 2.85µg/L were observed in the raw water and from 0.18 to 2.46µg/L in the treated water. Drinking water treatment plants using ozonation, granular activated carbon and chlorination have limited effectiveness in the removal of 1,4-dioxane. The results of this study are the first step towards bridging the knowledge gap in the occurrence of 1,4-dioxane in France.

A new strategy for volatile organics detection – Molecularly imprinted polymers-enabled headspace extracting and electrochemical sensing

The widely accepted method for detecting trace odor compounds such as 2-methylisoborneol (2-MIB) requires high-cost solid-phase microextraction coupled with gas chromatography-tandem mass spectrometry (SPME-GC/MS). As for now, cases that directly used SPME-GC/MS in the field are unseen, and most detection activities are still carried out in rigorous laboratory conditions. However, lengthy logistics and storage issues can compromise sample conditions, underscoring the significance of on-site detection methods. Here, we reported molecularly imprinted polymers-enabled headspace extracting and electrochemical sensing (MHEES) with the core feature of using the same piece of MIP for both headspace extracting and electrochemical sensing, allowing rapid on-site detection of trace 2-MIB in natural water bodies with a total cost of less than $2.10 per test. MHEES demonstrated exceptional sensitivity during extensively repeated laboratory experiments, achieving a detection limit of 3.7 ng∙L−1 and a standard deviation of 4.58 %. The practicality of MHEES was confirmed by conducting two rounds of on-site analyses on different reservoirs with fluctuating seasonal concentrations of 2-MIB. The developing flow of MHEES, from molecules docking to on-site application, was rigorous and could be cross-referenced to related research. The proposed MHEES design can potentially revolutionize the field of analytical chemistry by providing a versatile and affordable platform for on-site volatile compounds detection. It can readily adapt to various organic compounds and effectively address real-world challenges such as monitoring emerging pollutants, tracing disease biomarkers in body fluids, inspecting food safety, identifying chemical reaction intermediates, and supporting healthcare applications.

Targeted Metabolomic Analysis of Serum Free Fatty Acids: Lipidomics Disturbance in Patients with Superior Limbic Keratoconjunctivitis

This study aimed to identify and quantify free fatty acids (FFAs), secretory phospholipase A2 group IIa (sPLA2-IIa) and cytosolic phospholipase A2 (cPLA2) in serum of superior limbic keratoconjunctivitis (SLK) patients and explored the association between FFAs, sPLA2-IIa and cPLA2 variations and SLK. Targeted metabolomic analysis of FFAs in serum was performed by gas chromatography tandem mass spectrometry (GC-MS/MS) analysis on 16 SLK patients (43.88±7.88 years; female: 62.50%) and 25 healthy controls (43.12±7.88 years; female: 64.00%). Qualitative and absolute quantitative results of FFAs were obtained and classified according to gender and thyroid tests. Differential lipid metabolites, metabolomic pathways and biomarkers were further evaluated. The serum sPLA2-IIa and cPLA2 were determined by enzyme linked immunosorbent assay (ELISA).Among 40 FFAs identified, 6 FFAs showed significant changes (P<0.05) in SLK patients, including 4 decreased and 2 increased. They were mainly related to unsaturated fatty acid biosynthesis, α-linolenic acid and linoleic acid metabolism, and fatty acid biosynthesis. When dividing the data by gender or abnormal thyroid tests, some comparable FFAs alterations displayed in SLK patients. The ROC analysis revealed that the AUC values of linoleic acid, γ-linolenic acid, cis-8,11,14-eicosatrienoic acid, stearic acid, and palmitic acid, were all greater than 0.8. The serum concentrations of sPLA2-IIa and cPLA2 in patients with SLK were significantly higher than that in healthy controls. Lipidomics disturbance might be the potential mechanism of SLK. Serum FFA biomarkers associated with SLK have potential for the diagnosis and treatment of the disease.

Exploring sources of inaccuracy and irreproducibility in the CDC bottle bioassay through direct insecticide quantification

BackgroundThe Centers for Disease Control and Prevention (CDC) bottle bioassay is a commonly used susceptibility test for measuring insect response to insecticide exposure. However, inconsistencies and high variability in insect response when conducting CDC bottle bioassays have been reported in previous publications. We hypothesized that the CDC bottle bioassay results may be compromised when expected and actual insecticide concentrations in the bottles are not equivalent and that inadequate bottle cleaning and/or loss during insecticide introduction and bottle storage steps could be responsible. We explored this hypothesis by quantifying insecticides using gas chromatography tandem mass spectrometry (GC-MS/MS) in bottles that had been cleaned, prepared, and stored according to the CDC guidelines.MethodsWe investigated the bottle cleaning, preparation, and storage methods outlined in the CDC bottle bioassay procedure to identify sources of irreproducibility. We also investigated the effectiveness of cleaning bottles by autoclaving because this method is commonly used in insecticide assessment laboratories. The two insecticides used in this study were chlorpyrifos and lambda-cyhalothrin (λ-cyhalothrin). Insecticides were removed from glass bioassay bottles by rinsing with ethyl-acetate and n-hexane and then quantified using GC-MS/MS.ResultsThe CDC bottle bioassay cleaning methods did not sufficiently remove both insecticides from the glass bottles. The cleaning methods removed chlorpyrifos, which has higher water solubility, more effectively than λ-cyhalothrin. Chlorpyrifos experienced significant loss during the bottle-coating process whereas λ-cyhalothrin did not. As for bottle storage, no significant decreases in insecticide concentrations were observed for 6 h following the initial drying period for either insecticide.ConclusionsThe CDC bottle bioassay protocol is susceptible to producing inaccurate results since its recommended bottle cleaning method is not sufficient and semi-volatile insecticides can volatilize from the bottle during the coating process. This can lead to the CDC bottle bioassay producing erroneous LC50 values. High levels of random variation were also observed in our experiments, as others have previously reported. We have outlined several steps that CDC bottle bioassay users could consider that would lead to improved accuracy and reproducibility when acquiring toxicity data.Graphical

Enrichment and detection of polycyclic aromatic hydrocarbon in tea and coffee using phenyl-functionalized NiFe2O4@Ti3C2TX based magnetic solid-phase extraction

Polycyclic aromatic hydrocarbons (PAHs) are commonly found in various environmental matrices and have received significant attention due to their toxic effects on ecosystems and environmental health. In this study, a specific magnetic composite material derived from MXene, known as phenyl-functionalized NiFe2O4@Ti3C2TX, was designed and synthesized using a simple method. This composite material was used to develop an effective magnetic solid-phase extraction (MSPE) method for enriching trace polycyclic aromatic hydrocarbons (PAHs) in tea and coffee samples. The eluted PAHs were analyzed via gas chromatography–tandem mass spectrometry. Under optimal conditions, this method exhibited excellent linear relationships for 16 PAHs within the ranges of 0.001–25 and 0.0005–25 μg/L, with correlation coefficients exceeding 0.9979. The limits of detection for the target PAHs ranged from 0.1 to 0.3 ng/L. The effectiveness of the proposed method was evaluated by analyzing tea and coffee samples, and the satisfactory spiked recoveries of PAHs ranged from 84.5% to 112.6%.

Comparison of nitrogen and helium as carrier gases for determination of pesticide residues in foods via gas chromatography–tandem mass spectrometry with atmospheric pressure chemical ionization

The applicability of nitrogen as an alternative carrier gas to helium for the multiresidue analysis of pesticides using gas chromatography–tandem mass spectrometry with atmospheric pressure chemical ionization (GC–(APCI)MS/MS) was examined. The methods using both carrier gases were validated for 151 pesticides in foods at a spiking level of 0.01 ppm, maintaining identical conditions for both gases, including the GC column and carrier gas flow rate. The use of nitrogen resulted in slightly broader peaks and lower peak intensities that those observed upon using helium. However, sufficient sensitivity was achieved for all target compounds because of the high sensitivity of the GC–(APCI)MS/MS method. Further, target-compound separation was not significantly affected by the carrier gas type, and no interfering peaks were observed, demonstrating the high selectivity of the nitrogen-based method, even beyond the optimum linear velocity. Finally, the analytical performance of the nitrogen-based method was comparable to those of the helium-based method. Considering cost-effectiveness of nitrogen, this method is highly valuable in the event of helium shortages and for routine pesticide residue monitoring.

Prenatal exposure to polycyclic aromatic hydrocarbons and phthalate acid esters and gestational diabetes mellitus: A prospective cohort study

BackgroundPolycyclic aromatic hydrocarbons and phthalate acid esters (PAHs & PAEs), known as endocrine disrupting chemicals (EDCs), widely exist in daily life and industrial production. Previous studies have suggested that PAHs & PAEs may modify the intrauterine homeostasis and have adverse effects on fetal development. However, epidemiological evidence on the associations between PAHs & PAEs and gestational diabetes mellitus (GDM) is still limited. ObjectiveTo investigate the effects of prenatal PAHs &PAEs exposure on the risk of GDM and hyperglycemia in pregnant women. MethodsThe study population was a total of 725 pregnant women from a prospective birth cohort study conducted from December 2019 to December 2021. Blood glucose levels were collected by the hospital information system. Urinary PAHs & PAEs concentrations were determined by gas chromatography tandem mass spectrometry. The Poisson regression in a generalized linear model (GLM), multiple linear regression, quantile-based g-computation method (qgcomp), and Bayesian kernel machine regression (BKMR) were applied to explore and verify the individual and overall effects of PAHs & PAEs on glucose homeostasis. Potential confounders were adjusted in all statistical models. ResultsA total of 179 (24.69%) women were diagnosed with GDM. The Poisson regression suggested that a ln-unit increment of 4-OHPHE (4-hydroxyphenanthrene) (adjusted Risk Ratio (aRR) = 1.13; 1.02–1.26) was associated with the increased GDM risk. Mixed-exposure models showed similar results. We additionally found that MBZP (mono-benzyl phthalate) (aRR = 1.19; 1.02–1.39) was positively related to GDM risk in qgcomp model. Although neither model demonstrated that 2-OHNAP (2-hydroxynaphthalene) and 9-OHFLU (9-hydroxyfluorene) increased the risk of GDM, 2-OHNAP and 9-OHFLU exposure significantly increased blood glucose levels. BKMR model further confirmed that overall effects of PAHs & PAEs were significantly associated with the gestational hyperglycemia and GDM risk. ConclusionsOur study presents that environmental exposure to PAHs & PAEs was positively associated with gestational glucose levels and the risks of developing GDM. In particular, 2-OHNAP, 9-OHFLU, 4-OHPHE and MBZP may serve as important surveillance markers to prevent the development of GDM.

Systematic metabolomics study in the serum and urine of a mouse model of Fabry disease.

Fabry disease (FD) is an X-linked lysosomal disorder caused by α-galactosidase A enzyme activity deficiency. Although glycosphingolipid analogs have been identified in the plasma or urine of patients with FD, there is a limited understanding of altered metabolomics profiles beyond the globotriaosylceramide accumulation in FD. Metabolomics study was performed for monitoring of biomarker and altered metabolism related with disease progression in serum and urine from male α-galactosidase A knockout mice and age-matched wild-type mice at 20 and 40 weeks. Profiling analysis for metabolites, including organic acids, amino acids, fatty acids, kynurenine pathway metabolites, and nucleosides in the serum and urine was performed using gas chromatography-tandem mass spectrometry and liquid chromatography-tandem mass spectrometry combined with star symbol patterns and partial least squares discriminant analysis (PLS-DA). A total of 27 and 23 metabolites from the serum and urine of Fabry mice were distinguished from those of wild-type mice, respectively, based on p-value (<0.05) and variable importance in projection scores (>1.0) of PLS-DA. In the serum, metabolites of the glutathione, glutathione disulfide, citrulline, and kynurenine pathways that are related to oxidative stress, nitric oxide biosynthesis, and inflammation were increased, whereas those involved in pyruvate and tyrosine metabolism and the tricarboxylic acid cycle were altered in the 20- and 40-week-old urine of FD model mice. Altered metabolic signatures associated with disease progression by oxidative stress, inflammation, nitric oxide biosynthesis, and immune regulation in the early and late stages of FD.

Impact of Bacillus subtilis on Chinese yellow rice wine (Huangjiu) fermentation: Method variations and flavor analysis

This investigation explores the impact of various fermentation techniques and the inoculation of Bacillus subtilis spores on the physicochemical properties and principal flavor profiles of Huangjiu. Employing sensory analysis, headspace solid-phase microextraction, gas chromatography-tandem mass spectrometry (HS-SPME-GC–MS), and orthogonal partial least squares discriminant analysis (OPLS-DA), we observed that these variables significantly alter the physicochemical attributes of Huangjiu. Our analysis, integrating volatile organic compounds (VOCs) with odor activity values (OAV), revealed that while B. subtilis inoculation modifies the concentrations of key flavor compounds, it does not affect their types. Notably, the inoculation enhances the concentrations of 13 primary flavor compounds, thereby enriching floral and fruity notes while reducing higher alcohol levels. These findings contribute valuable insights into the flavor formation mechanisms of Huangjiu and guide the optimization of fermentation processes.

Better Together: Tandem Mass Spectrometry Achieves up to 50 Times Lower Quantification of 62 Disinfection Byproducts in Drinking Water.

Disinfection byproducts (DBPs) are ubiquitous contaminants present in nearly all drinking water and are associated with adverse health effects in human epidemiologic studies. The most toxic DBPs are unregulated and often occur at concentrations well below regulated DBPs; thus, quantification at low parts-per-trillion (ng/L) levels is critical in assessing exposure. We developed a new liquid-liquid extraction-gas chromatography-tandem mass spectrometry (LLE-GC-MS/MS) method with the first analysis by tandem gas chromatography-mass spectrometry of 23 priority unregulated DBPs including 13 haloacetamides, 3 haloacetic acids, 2 haloacetonitriles, 1 haloacetaldehyde, 2 haloketones, and 2 halonitromethanes. When combined with our previous GC-MS/MS method for haloacetic acids and previously reported MS/MS transitions that we optimized for this method, the analysis of 62 regulated and priority unregulated DBPs at lower quantification limits is achieved. Limits of quantification for most DBPs were between 5 and 30 ng/L with r2 > 0.99 and an average of 9 times lower limits of quantification (LOQs) compared to LLE-GC-MS using selected ion monitoring (SIM). Relative standard deviations ranged from 0.7 to 30% for 61 DBPs in spiked samples. This new method was validated using tap waters from four US cities, where individual DBP concentrations ranged from 5 to 126,882 ng/L. This project provides the most comprehensive GC-MS/MS method for DBP analysis to date and is capable of analyzing volatile and semivolatile DBPs across nine different compound classes, including a class not previously analyzed by GC-MS/MS.

Determination of multi-residue pesticides in dairy products using single-step emulsification/demulsification clean-up strategy combined with low-pressure gas chromatography-tandem mass spectrometry

In this study, a simple, sensitive, and rapid method was developed for the simultaneous determination of 99 kinds of pesticides in fatty milk samples. This novel emulsification-demulsification clean-up approach, coupled with an automatic demulsification-dehydration cartridge, allowed rapid single-step clean-up operation and high throughput. It also achieved effective and selective removal of lipids. The analysis was performed using low-pressure gas chromatography-tandem mass spectrometry (LPGC–MS/MS). Based on the optimal conditions, the targeted pesticides showed good linearity in the range of 5–250 μg/kg, with recoveries of 70–120% at spiking levels of 5, 10, and 20 μg/kg in cow milk, goat milk, and almond milk, respectively. The limit of quantification for most pesticides was 5 μg/kg, and the RSDs were lower than 20%. Analysis of real dairy products obtained from local markets revealed a potential risk in plant-derived almond milk, but no significant risks were found for cow and goat milk.

Characterization of Cichorium intybus L. Extract in Preventing Oxidative DNA Base Damage Using Gas Chromatography–Tandem Mass Spectrometry (GC–MS/MS)

Free radicals are unstable and are known for electron deficiency. This state renders DNA, proteins, and various biomolecules susceptible to detrimental interactions, leading to damage. However, this process can be regulated by antioxidants produced naturally on-site or externally through food or herbal supplements. In recent years, interest in characterizing alternative, natural and safe antioxidants obtained from plant sources has been increasing. Within this context, Cichorium intybus L. has garnered attention for its notable antioxidant content. In our previous study, we determined optimum conditions for ultrasound-assisted extraction of antioxidants from Cichorium intybus L. using central composite design-response surface methodology. In this study, the quantitative determination of phenolics in the extract prepared under optimal conditions was undertaken employing high-performance liquid chromatography with diode array detection (HPLC-DAD). The study’s primary goal is to investigate the impact of the extract derived from Cichorium intybus on the formation of products resulting from oxidative damage to DNA bases by gas chromatography–tandem mass spectrometry (GC–MS/MS). For this purpose, different volumes of extract were added to the DNA + Fenton medium. When 25 µL of extract were added, 239.98 ± 5.81 ng of damaged product/mg DNA was present. 233.12 ± 5.63 ng of damaged product/mg DNA were obtained for 50 µL of extract and 165.76 ± 4.58 ng of damaged product/mg DNA for 100 µL. This study shows that Cichorium intybus has potential therapeutic effects on supporting antioxidant defenses and reducing oxidative DNA damage.

Quantification of antidepressants in oral fluid and plasma samples using microextraction by packed sorbent and analysis by gas chromatography-tandem mass spectrometry

The consumption of antidepressants is extremely significant as they are a class of medications widely used in the treatment of numerous disorders and are therefore considered a public health problem throughout the world. The aim of this work was to develop and optimize two methodologies for the determination of selected antidepressants and metabolites (fluoxetine, venlafaxine, O-desmethylvenlafaxine, citalopram, sertraline, paroxetine), in 250 µL of sample (oral fluid and plasma) using microextraction by packed sorbent (MEPS) as the extraction technique and gas chromatography coupled to tandem mass spectrometry (GC–MS/MS) for analysis. The two methods were fully validated considering the internationally accepted criteria for bioanalytical procedures, presenting linearity within the studied range, with limits of quantification between 10 and 100 ng/mL, coefficients of determination (R2) of at least 0.99 and precision and accuracy with acceptable values of coefficients of variation and relative errors for all antidepressants in study and for both specimens. Recoveries ranged between approximately 12 and 93 % for oral fluid samples and between approximately 28 and 101 % for plasma samples. To our best knowledge, the described methods are the first to be reported using MEPS and GC–MS/MS for the identification of antidepressants in oral fluid and plasma samples, proving to be sensitive, simple, fast and capable of being applied in routine clinical and forensic toxicology scenarios.

A fungal hyphae-derived biomass carbon for magnetic solid-phase extraction of the organochlorine pesticides in water samples, tea beverages, and Chinese traditional medicines before gas chromatography-tandem mass spectrometry determination

A magnetic biochar nanomaterial derived from fungal hyphae was introduced into the sample preparation field. The magnetic fungal hyphae-derived biomass carbon (MFHBC) could be produced by a controllable hydrothermal method. In order to obtain the best sorbent for magnetic solid-phase extraction (MSPE), the reaction conditions containing temperature, time and the consumption of fungal hyphae were investigated. A series of MFHBC materials were characterized by vibrating sample magnetometers, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and transmission electron microscopy. A material with a satisfactory saturation magnetization (21.58 emu g-1) and largest surface area (88.06 m2 g-1) was selected as the sorbent to extract ten typical organochlorine pesticides (OCPs). The extraction conditions were optimized as 20 mL of sample solution with 70 mg of sorbent and 2.0 g of NaCl oscillated at 50 °C for 5.0 min. And the optimum desorption was performed by oscillating sorbent in 1.0 mL acetonitrile for 5.0 min. Then, the MFHBC-based MSPE-GC–MS/MS methods were established for different samples including water samples, tea beverages, and Chinese traditional medicines. The linearities were 10–2500 ng L−1 or 100–25,000 ng kg−1, and the limits of detection were 0.3–13.9 ng L−1 for water sample, 0.1–9.7 ng L−1 for tea beverage samples, 0.1–21.4 ng L−1 for Shenqi Fuzheng injection samples, and 7.2–278.3 ng kg−1 for Astragali Radix decoction pieces. Except for satisfactory repeatability (RSDs ≤13.8%) in intra-day and inter-day tests (n = 3), the reproducibility (RSDs ≤13.5%, n = 3) of MFHBC was acceptable. The methods were applied in the determination of OCPs from above real samples, with the recoveries of 80.5–117.2% and the RSDs (n = 3) <8.9%. The methods were suitable in the sensitive determination of OCPs from simple to complex matrix samples.

Discrimination and simultaneous quantification of poly(ethylene terephthalate) and poly(butylene terephthalate) microplastics in environmental samples via gas chromatography-tandem mass spectrometry.

A method has been developed to quantify PET and PBT microplastics (MPs) based on depolymerization and detection of depolymerization products by gas chromatography-tandem mass spectrometry (GC-MS/MS) without a complex separation process from environmental samples. Under the optimal depolymerization conditions, PET and PBT were efficiently convertedto ethylene glycol (78%) and 1,4-butanediol (87%), respectively. Subsequently, the linear curves were constructed between signal intensities of depolymerization products and polymer masses by GC-MS/MS, and the correlation coefficients of PET and PBT were 0.996 and 0.997, respectively. The spiking and recovery experiments of PET and PBT in the environmental samples showed that the recovery was stable in the range 89-100%, and the limit of detection was 4.95μg and 1.39μg of PET and PBT, respectively. The method has been proven to be capable of simultaneous identification and quantification of PBT and PET MPs in real environmental water samples without complex separation process, which provided a scheme for the determination of microplastics.

Migration characteristics and risk assessment of chemical hazardous substances in infant teether toys

Teether is a special toy used for infants oral contact. In this paper, a residual and migration detection method was developed using gas chromatography–tandem mass spectrometry for 20 screened hazardous substances in teethers. Fifteen substances were detected in 59 samples, with residual amounts and detection rates ranging from 0.01 mg⋅kg−1 to 106.15 mg⋅kg−1 and from 3.39 % to 84.7 % respectively. Then, 12 substances were detected in simulated saliva at migration levels ranging from 0.0143 mg⋅kg−1 to 20.03 mg⋅kg−1, with detection rates ranging from 1.69 % to 76.3 %. Statistically, the average migration rate of each substance ranged from 8.18 % to 53.28 % depending on the properties of the substance and the sample. The exposure risk of infants to teethers was evaluated separately for two age groups. The hazard quotient (HQ) and hazard index (HI) values for the analytes were higher in the 3–12-month age group than in the 12–24-month age group. The HQ values of triphenylphosphine oxide, benzocaine, and N-methylformanilide were relatively high, with averages of 1.2 × 10−2, 2.5 × 10−3, and 1.6 × 10−3, respectively, and the max HI of the 12 substances was 0.04. The HI and HQ values of the analytes were all below 1, indicating that the non-carcinogenic risks of analytes in teethers are at an acceptable level.

Associations between exposure to pesticides mixture and semen quality among the non-occupationally exposed males: Four statistical models

Most epidemiological studies on the associations between pesticides exposure and semen quality have been based on a single pesticide, with inconsistent major results. In contrast, there was limited human evidence on the potential effect of pesticides mixture on semen quality. Our study aimed to investigate the relationship of pesticide profiles with semen quality parameters among 299 non-occupationally exposed males aged 25–50 without any clinical abnormalities. Serum concentrations of 21 pesticides were quantified by gas chromatography-tandem mass spectrometry (GC-MS/MS). Semen quality parameters were abstracted from medical records. Generalized linear regression models (GLMs) and three mixture approaches, including weighted quantile sum regression (WQS), elastic net regression (ENR) and Bayesian kernel machine regression (BKMR), were applied to explore the single and mixed effects of pesticide exposure on semen quality. In GLMs, as the serum levels of Bendiocarb, β-BHC, Clomazone, Dicrotophos, Dimethenamid, Paclobutrazole, Pentachloroaniline and Pyrimethanil increased, the straight-line velocity (VSL), linearity (LIN) and straightness (STR) decreased. This negative association also occurred between the concentration of β-BHC, Pentachloroaniline, Pyrimethanil and progressive motility, total motility. In the WQS models, pesticides mixture was negatively associated with total motility and several sperm motility parameters (β: −3.07∼-1.02 per decile, FDR-P<0.05). After screening the important pesticides derived from the mixture by ENR model, the BKMR models showed that the decreased qualities for VSL, LIN, and STR were also observed when pesticide mixtures were at ≥ 70th percentiles. Clomazone, Dimethenamid, and Pyrimethanil (Posterior inclusion probability, PIP: 0.2850–0.8900) were identified as relatively important contributors. The study provides evidence that exposure to single or mixed pesticide was associated with impaired semen quality.

Identification of phytoconstituents from Houttuynia cordata Thunb. as dipeptidyl peptidase-IV and sodium glucose cotransporter 2 inhibitors guided by molecular docking

PurposeHouttuynia cordata Thunb. is an edible medicinal herb belonging to the Saururaceae family. Although the effects of the plant extracts on several diabetic-related parameters have been documented in the past, there is no documentation of the effects of this plant on sodium/glucose cotransporter 2 or dipeptidyl peptidase-IV- key drug targets for type 2 diabetes. The present study identified and screened phytoconstituents present in H. cordata Thunb. and characterized their ADME/Tox properties. The compounds present in aqueous and hydroalcoholic extracts of H. cordata Thunb. were identified using High-Performance Thin Layer Chromatography, and Gas Chromatography tandem mass spectrometry. Compounds obeying the Lipinski's Rule of 5 and having high gastrointestinal absorption were then selected and docked with dipeptidyl peptidase-IV and sodium/glucose cotransporter 2. ResultsChromatographic analysis showed the presence of several compounds by matching their recorded spectra with the data bank mass spectra from the NIST library. ADME/Tox properties and docking of the identified compounds indicate the potentiality of the compounds as antidiabetic drug candidates. ConclusionsThe compounds from Houttuynia cordata have good binding affinities to peptidase-IV and sodium/glucose cotransporter 2 and can therefore be used as their inhibitors. However, isolation of these phytoconstituents and their in vivo activity will help give a better insight and will open a new area of investigation of individual components and their pharmacological potency.

Determination of chloropropanol esters and glycidyl esters in nutritional foods by gas chromatography–tandem mass spectrometry based on acid hydrolysis and solid-phase extraction

This study presents a method based on acid transesterification and the purification by solid-phase extraction (SPE) coupled with gas chromatography–tandem mass spectrometry for quantifying 3- and 2-monochloropropanediol esters (3-MCPDE, 2-MCPDE) and glycidyl esters (GE) in nutritional foods. The fat was extracted by liquid–liquid extraction with petroleum ether and diethyl ether after the sample was hydrolysed with ammonia. Then the extract was purified by a SPE cartridge filled with the aminopropyl sorbents. It was demonstrated that the optimal elution volume for 3-MCPDE, 2-MCPDE and GE greatly depended on the sample matrix and varied from 6 to 12 mL for four different kinds of food matrices. All three analytes in the sample solution could be fully collected in the first 10–12 mL of eluate. By this way, monoacylglycerols commonly present in the samples were fully removed. Therefore, the overestimation of GE quantification was effectively eliminated. The modified analytical procedure was fully validated in a single laboratory and has been recommended as a Chinese Food Safety National Standard. In addition, two derivatisation agents, heptafluorobutyrylimidazole and phenylboronic acid, were proved to be equivalent in method accuracy and precision for the quantification of three analytes.

A multi-technique based analytical platform for characterization and identification of a newly emerged steroid 6β-chlorotestosterone and its in-vivo epimeric metabolites

Doping athletes tend to use new and non-approved drugs in an attempt to circumvent the dope test. Recently, a package of unknown drug was obtained from black market claiming to contain steroid-like compound, which could not be readily identified due to the lack of commercially available reference standards. In order to characterize and identify the chemical structure of the unknown compound, ultra performance liquid chromatography high resolution mass spectrometry (UPLC-HRMS), high performance liquid chromatography tandem quadrupole mass spectrometry (HPLC-MS/MS), gas chromatography tandem quadrupole mass spectrometry (GC–MS/MS) and nuclear magnetic resonance (NMR) instruments were applied in this work. Based on the combined data, the unknown compound was identified as 6β-chlorotestosterone. The aim of this study was to find urinary metabolic biomarkers of 6β-chlorotestosterone for clinical research and doping control analysis. Ten in-vivo metabolites including four phase I metabolites and six phase II metabolites were characterized and potentially identified. The detailed structure of the phase I metabolite was successfully obtained by GC–MS/MS analysis of trimethylsilylation (TMS) released upon dissolution, overcoming the absence of useful fragment ions to demonstrate the structure of sulfate metabolites. Two strategies including metabolic mechanisms and retention time variation of steroids were introduced to determine and distinguish 3α/β- and 5α/β- epimeric metabolites. A comprehensive evaluation was conducted on time of appearance and detection of each metabolite. The sulfate metabolite 6β-chloro-5β-androstan-17-one-3β-O-sulfate (S1) could be detected up to 12 days after oral administration, which was considered to be the long term biomarker for 6β-chlorotestosterone abuse in clinical research and doping control analysis.