Gas Chromatography-tandem Mass Spectrometry Research Articles

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.

Advanced Mass Spectrometry-Based Biomarker Identification for Metabolomics of Diabetes Mellitus and Its Complications.

Over the years, there has been notable progress in understanding the pathogenesis and treatment modalities of diabetes and its complications, including the application of metabolomics in the study of diabetes, capturing attention from researchers worldwide. Advanced mass spectrometry, including gas chromatography-tandem mass spectrometry (GC-MS/MS), liquid chromatography-tandem mass spectrometry (LC-MS/MS), and ultra-performance liquid chromatography coupled to electrospray ionization quadrupole time-of-flight mass spectrometry (UPLC-ESI-Q-TOF-MS), etc., has significantly broadened the spectrum of detectable metabolites, even at lower concentrations. Advanced mass spectrometry has emerged as a powerful tool in diabetes research, particularly in the context of metabolomics. By leveraging the precision and sensitivity of advanced mass spectrometry techniques, researchers have unlocked a wealth of information within the metabolome. This technology has enabled the identification and quantification of potential biomarkers associated with diabetes and its complications, providing new ideas and methods for clinical diagnostics and metabolic studies. Moreover, it offers a less invasive, or even non-invasive, means of tracking disease progression, evaluating treatment efficacy, and understanding the underlying metabolic alterations in diabetes. This paper summarizes advanced mass spectrometry for the application of metabolomics in diabetes mellitus, gestational diabetes mellitus, diabetic peripheral neuropathy, diabetic retinopathy, diabetic nephropathy, diabetic encephalopathy, diabetic cardiomyopathy, and diabetic foot ulcers and organizes some of the potential biomarkers of the different complications with the aim of providing ideas and methods for subsequent in-depth metabolic research and searching for new ways of treating the disease.

Thiocarbamide conversion-based nitrogen-rich covalent organic framework coatings for electro-enhanced solid-phase microextraction of bisphenols

Design and preparation of fiber coatings with excellent electrochemical performance and high polarity is significant for efficient extraction of polar targets in electro-enhanced solid-phase microextraction (EE-SPME). In this work, a combination strategy for structure regulation of covalent organic framework (COF) was proposed to fabricate a nitrogen-rich thiocarbamide linked COF coating (Thiocarbamide-TZ-DHTP) via molecular design and post-synthetic thiocarbamide conversion. The prepared COF coating possesses a large number of O, N, and S functional groups, which not only endow the coating with higher polarity but also significantly enhance its electrochemical performance. The COF coating was used for EE-SPME of polar bisphenols (BPs), demonstrating excellent enrichment efficiency and durability. Subsequently, coupled with gas chromatography-tandem mass spectrometry (GC-MS/MS), a sensitive method was developed for determination of trace BPs. The established method possess wide linear ranges (2.0–800.0 ng L−1), good correlation coefficients (0.9985–0.9994) and low detection limits (0.1–2.0 ng L−1). Moreover, the established method had been successfully applied to detection of trace BPs in tea beverage with satisfactory recoveries (81.6 % to 118.6 %). This research provides a feasible pathway for preparing COF coating with excellent electrochemical performance and high polarity for EE-SPME.

Development of a highly sensitive method based on QuEChERS and GC-MS/MS for the determination of polycyclic aromatic hydrocarbons in infant foods.

Polycyclic aromatic hydrocarbons (PAHs) are environmental contaminants that can be found in various food products, including those intended for infants. Due to their potential health risks, it is crucial to develop sensitive analytical methods for the accurate determination of PAHs in infant foods. This study describes the development and validation of a highly sensitive method for the quantification of European PAH markers, namely benzo[a]pyrene, benzo[a]anthracene, chrysene, and benzo[b]fluoranthene, using gas chromatography-tandem mass spectrometry (GC-MS/MS), in baby food samples. The first step was the optimization of the sample preparation procedure, performed using different methods based on the QuEChERS approach, also testing different extraction solvents. Several factors such as extraction efficiency, selectivity, and recovery were evaluated to choose the most effective procedure for sample preparation. Furthermore, the GC-MS/MS method was optimized, evaluating parameters such as linearity, sensitivity, accuracy, and robustness using spiked infant food samples. The method demonstrated excellent linearities with a correlation coefficient higher than 0.999 over a wide concentration range, and limits of detection and limits of quantification in the range 0.019-0.036 μg/kg and 0.06-0.11 μg/kg, respectively. Extraction recoveries were between 73.1 and 110.7%, with relative standard deviations always lower than 8%. These findings are compliant with the indications of the European Commission (Reg. 836/2011). To assess the applicability of the method to official control activities, a survey was conducted on commercially available infant food products. Four markers were determined in commercial samples belonging to different food categories for infants and young children. The outcome of this monitoring showed that PAH contamination, in all samples, was below the quantification limits. In conclusion, the developed GC-MS/MS method provides a highly sensitive and reliable approach for the determination of PAHs in baby foods. The optimized sample preparation, instrumental parameters, and validation results ensure accurate quantification of 4 PAHs even at trace levels. This method could contribute to the assessment of PAH exposure in infants and it could support regulatory efforts to ensure the safety and quality of infant food products with regular monitoring.

Determine the pharmacokinetics (half-life, volume of distribution and clearance) of AMB-FUBINACA in rats plasma using GC–MS / MS

BackgroundSeveral novel synthetic cannabinoids, including methyl 2-(1-(4-fluorobenzyl)-1Hindazole-3-carboxamido)-3-methylbutanoate (AMB-FUBINACA), have recently surfaced on the illicit drug market. To determine the pharmacokinetic properties (half-life, volume of distribution, and clearance) of AMB-FUBINACA in rats plasma, a straightforward, quick, and highly sensitive analytical approach was developed. MethodsEighteen Wistar rats were divided into two groups: one control (saline vehicle) and one treatment group (AMB-FUBINACA at 50 mg/kg). Blood samples (400 μL) were withdrawn via catheters immediately before (t = 0) and at 30, 60, 90, 120, and 240 min following injection. Samples were collected into 1 mL tuberculin syringes, then transferred to 1.5 mL plastic tubes containing 5 μL of 1000 IU/mL K3-EDTA (Thomas Scientific). Place the EDTA tubes containing samples in a centrifuge and spin at 1000 g for 10 min at 4 °C. The top layer is the plasma fraction, which is decanted into cryovials and stored at −20 °C until analysis. The gas chromatography tandem mass spectrometry (GC–MS/MS) method was optimized and validated, combined with liquid-liquid extraction, to analyze AMB-FUBINACA in rat plasma. ResultsThe research method successfully met the validation requirements set by the FDA, demonstrating selectivity and linear calibration curves within a concentration range of 0.5–1000 ng/ml. The correlation coefficient (r2) was determined to be 0.99, indicating a strong linear relationship. The analyte's limit of quantitation (LOQ) was determined to be 1–5 ng/mL. Subsequently, the method was successfully applied to investigate the pharmacokinetics of AMB-FUBINACA in rats' blood samples. Following oral administration, AMB-FUBINACA was rapidly absorbed, with a plasma half-life (t1/2) of 5.91 h, a volume of distribution (Vd) of 203.13 l, and a plasma clearance of 23.81122 L/h. ConclusionThese findings contribute to the understanding of AMB-FUBINACA's pharmacokinetics and pharmacodynamics.

Assessment of Malondialdehyde and Organochlorine Pesticides in Aplastic Anemia Severity Groups: Insights Into Oxidative Stress and Exposure.

Background There is little evidence that pesticide exposure is the primary cause of acquired aplastic anemia (AAA), even though the prevalence of aplastic anemia (AA) is substantially higher in underdeveloped countries than in affluent countries. AA caused by pesticides has not yet been fully understood. This study aimed to examine the potential link between plasma levels of malondialdehyde (MDA) and organochlorine pesticides (OCPs) as risk factors for developing AAA in the North Indian population. Methods This case-control study was conducted at a tertiary care hospital in North India. A total of 99 participants were chosen for the study, of whom 45 were cases of AA. These cases attended the Clinical Hematology department over a period of 1.5 years (May 2018 to November 2019). Forty-five controls were age and sex-matched, apparently healthy subjects. Written informed consent was obtained from each subject before performing the study. Exclusion criteria included patients unwilling to give consent, those using medication to treat AA, those genetically predisposed to AA, those with characteristics including granuloma and dysplasia of bone marrow, any other systemic illness, and subjects with a history of smoking, drinking, or using tobacco in any form. Gas chromatography-tandem mass spectrometry (GC-MS/MS) was used to evaluate the plasma levels of organochlorines. The estimation of plasma MDA, i.e., the lipid peroxide content, was measured. Results The severity of AA is significantly associated with plasma levels of α-Hexachlorocyclohexane (p = 0.040), Heptachlor (p = 0.006), Aldrin (p < 0.001), p,p'-Dichlorodiphenyldichloroethane (p = 0.004), Endosulfan sulfate (p = 0.010), and Methoxychlor (p = 0.001). There was a statistically non-significant difference in MDA levels between cases and controls (p = 0.145); however, a statistically significant linear increase in MDA levels (p < 0.001) was observed according to the severity of AA. Conclusion Our study suggests that oxidative stress may be linked to the severity of AA. Pesticide exposure (plasma organochlorine levels) could act as a stressor, potentially initiating an alarmin response of oxidative stress in the form of lipid peroxidation (MDA) from damaged tissue, which could then lead to suppression of hematopoiesis and be a possible factor in the development of AA.

Validation of a modified QuEChERS method for the quantification of residues of currently used pesticides in Cuban agricultural soils, using gas chromatography tandem mass spectrometry

We present an analytical method to detect and quantify residues of currently used pesticides (CUPs), which include 31 active ingredients (ai) and seven transformation products (TPs) in tropical and agricultural soils of Cuba. Ten isotopically labeled analogous compounds served as internal standards (IL-IS). The novelty of this research is the inclusion of different tropical soils type scarcely studied for CUPs and TPs, based on the QuEChERS (quick, easy, cheap, effective, rugged and safe) method, followed by chromatography tandem mass spectrometry. All figures of merit proved to be satisfactory according to SANTE guidelines 2020 and 2021. Matrix effects (ME) calculated by the external standard method were significant (|ME| > 20% for almost all compounds; grand mean ± standard deviation (STD) 104 ± 108%) in all soils. The internal standard method compensated ME to non-significant levels (8 ± 50%), even for analytes with a non-structure identical IL-IS (STD, 13 ± 57%). Repeatability (relative standard deviation, RSDr) and reproducibility (RSDR) for skeletic regosol (SR) were 7.5 ± 2.8% and 11.7 ± 4.7%, respectively. Absolute (quantified for 11 analytes with structure identical IL-IS) and relative recovery from SR was 92 ± 13% (mean ± STD) and 90 ± 12%, respectively. Limits of quantification for SR ranged from 0.1 to 10 ng/g, except metalaxyl and oxyfluorfen (25 ng/g each). Linearity of matrix-matched (MM) calibration curves (5 to 100 ng/g) had an R2 of ≥ 0.99 for all soils and almost all analytes. The method was successfully applied to 30 real soil samples.

Gas chromatography-stable isotope ratio mass spectrometry prior solid phase microextraction and gas chromatography-tandem mass spectrometry: development and optimization of analytical methods to analyse garlic (Allium sativum L.) volatile fraction

Garlic (Allium sativum L.) is not only appreciated for its flavour and taste, but it is also recognized for various health properties. The European Commission, through the attribution of the Protected Designation of Origin (PDO) certification mark, has officially recognized some specific varieties of garlic. To protect not only the commercial value but also the reputation of this appreciated product, effective tools are therefore required. For the first time, a new compound specific isotope analysis method based on carbon stable isotopic ratio measurement of the three major volatile garlic compounds allyl alcohol (AA), diallyl disulphide (DD) and diallyl trisulphide (DT) through head-space solid phase microextraction (HS-SPME) followed by gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) was developed. A within-day standard deviation (Srwithin-day) of 0.3 ‰, 0.4 ‰ and 0.2 ‰ for δ(13C) and a between-day standard deviation (Srbetween-day) of 0.8 ‰, 1.0 ‰ and 0.6 ‰ of AA, DT and DD was estimated. For the first time, the ranges of isotopic variability for the three volatile compounds of red garlic from two neighbouring Italian regions (Abruzzo and Lazio) were defined analysing 30 samples. The same dataset was also considered in analysing the percentage composition of the previously mentioned three volatile compounds through HS-SPME followed by gas chromatography-tandem mass spectrometry (GC-MS/MS). The two analytical approaches were combined in this explorative study, aiming to provide potential parameters to discriminate garlic samples based on their geographical origin.

Metabolomic analysis reveals the changing trend and differential markers of volatile and nonvolatile components of Artemisiae argyi with different aging years.

Artemisia argyi Folium (AAF) is a traditional medicinal herb and edible plant. Analyzing the differential metabolites that affect the efficacy of AAF with different aging years is necessary. The aim of the study was to investigate the changing trend and differential markers of volatile and nonvolatile metabolites of AAF from different aging years, which are necessary for application in clinical medicine. Metabolites were analyzed using a widely targeted metabolomic approach based on ultrahigh-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) and gas chromatography tandem mass spectrometry (GC-MS). A total of 153 volatile metabolites and 159 nonvolatile metabolites were identified. Principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) could clearly distinguish AAF aged for 1 year (AF-1), 3 years (AF-3), and 5 years (AF-5). Seven flavonoids and nine terpenoids were identified as biomarkers for tracking the aging years. The metabolomic method provided an effective strategy for tracking and identifying biomarkers of AAF from different aging years. This study laid the foundation for analysis of the biological activity of Artemisia argyi with different aging years.

The effect of farming techniques on degradation of DDT in historical cotton farms

DDT was used in the mid 20th century for crop and livestock production. After use, DDT and its degradates DDE and DDD (collectively DDX) remain in the environment for decades. A few studies have reported that the rate of degradation of DDT into its metabolites is affected by various farming techniques like tillage, irrigation, and use of fertilizers. However, most of these studies did not evaluate active farms, and none of them focused on the Southeast US or historical cotton farms. Therefore, in this study, we aimed to determine if different farming techniques affect the decomposition of DDT in Walton County, Georgia, where farms historically grew cotton. Five Walton County farms were sampled for soil, and churches were sampled as control sites. The extensive land history of the farms was recorded, and the soil levels of p,p’-DDT, p,p’-DDE, p,p’-DDD, o,p’-DDT, and o,p’-DDE were measured using gas chromatography-tandem mass spectrometry. All farm sites had detectable levels of p,p’-DDT, p,p’-DDE, and p,p’-DDD, while few sites had detectable levels of o,p’-DDT and o,p’-DDE. Tillage was found to speed up p,p’-DDE degradation, but there was no effect on p,p’-DDT degradation. Plowing was associated with an increase in decomposition of p,p’-DDT, but p,p’-DDE and p,p’-DDD were not significantly increased. The largest difference in the degradation of DDT was based on the fertilizer type. Natural fertilizer sped up degradation of p,p’-DDT and p,p’-DDE; synthetic fertilizer increased p,p’-DDE degradation, but not p,p’-DDT degradation.

Biocide and other semi-volatile organic compound concentrations in settled indoor dust of CRESPI daycare centers and implication for public health

This study investigates the presence of biocides and other semi-volatile organic compounds (SVOCs) in cleaning products used in daycare centers and health impact through ingestion of settled dust by young children. In Paris metropolitan area, 106 daycares area were investigated between 2019–2022. Fifteen substances were analyzed in settled indoor dust by gas chromatography-tandem mass spectrometry. Detection rates and concentrations ranged from 5 to 100%, and <LOD to 14,267 ng/g, respectively. Galaxolide and benzophenone showed highest median concentration respectively 884 ng/g and 819 ng/g. The daily intakes (DI) of the substances through settled dust ingestion were evaluated and compared to those from food, inhalation, and dermal contact reported in the literature. Daily intakes from settled dust for musks, triclosan, geraniol, benzophenone, 2-phenylphenol, bifenthrin, and 4-n-nonylphenol were lower than those reported in the literature. The proportion of dust ingestion to total DI was negligible, except for benzophenone (DI=34%) for children aged 3 to 11 months. The DIs were well below the respective toxicological reference values for isothiazolinones, 4-tert-butylphenol, chlorocresol, and diclosan. Our results suggest that exposure to these biocides and the other SVOCs, taken individually, by dust ingestion in daycares, is not a major public health concern. Benzophenone, presumed carcinogen for humans, may require further investigation because of its presence in several daycares.

Rapid determination of polyhalogenated carbazoles in water chestnut based on vortex assisted solvent extraction coupled with dispersive filter extraction followed by gas chromatography-tandem mass spectrometry

Polyhalogenated carbazoles (PHCZs), originating from the production and use of halogenated indigo dyes, photoelectric materials, and p-chloraniline structure herbicides, pose a threat to water environments, aquatic products, and consequently human health. Therefore, establishing an accurate detection method for PHCZs in aquatic products is of paramount importance. In this study, trace PHCZs (36-CCZ, 36-BCZ, and 1368-BCZ) in water chestnut were detected for the first time using the prepared polyvinyl alcohol-functionalized graphene aerogel (PGA) as a novel adsorbent for dispersive filter extraction (DFE), coupled with vortex assisted solvent extraction (VASE), followed by gas chromatography-tandem mass spectrometry (GC–MS/MS). The extraction process (VASE-DFE) has the advantages of good purification effect, short extraction time (<15 min), and low adsorbent dosage (1.0 mg). This method demonstrated excellent linearity in the range of 0.10/0.50/1.00–200 ng/g for the three PHCZs (R2 ≥ 0.9995), and the recoveries at three spiked levels (2, 20, 100 ng/g) ranged from 82 % to 93 %, with relative standard deviations (RSDs) ≤ 7.4 %. Notably, the method outperforms previously reported adsorbents in terms of RSDs, adsorbent dosage, and extraction time. The VASE-DFE-GC–MS/MS method provides a new approach for the detection of trace pollutants in complex samples, introduces a novel technology for environmental and food safety monitoring, and contributes to enhancing food safety supervision.

Quantifying 209 Polychlorinated Biphenyl Congeners in Silicone Wristbands to Evaluate Differences in Exposure among Demolition Workers.

A social housing estate in Denmark was designated for demolition due to exceedance of guidance values for polychlorinated biphenyls (PCBs) in indoor air. Here, we deployed precleaned silicone wristbands (n = 46) among demolition workers of these contaminated buildings during single workdays while conducting various work tasks. We established a method to analyze all 209 PCBs in wristbands to identify prominent congeners of exposure and evaluate differences between tasks. Wristbands were extracted using microwave-assisted extraction and then concentrated for gas chromatography-tandem mass spectrometry (GC-MS/MS) analysis. Twenty-nine chromatographic peaks representing 37 congeners were detected in every wristband, and tetra-CBs were the dominant homologue group. PCB-66, -44, and -70 were the most abundant congeners measured in worker wristbands, none of which are included within the typical seven indicator or WHO 12 PCBs. Workers who cut PCB-containing sealants had wristbands with the highest PCB concentrations (geometric mean ∑209PCBs = 1963 ng/g wristband), which were followed by those handling concrete elements on the building roof. Additionally, wristbands captured a broader range of PCBs than has been previously measured in air and serum samples. Taken together, our results highlight the importance of total congener analysis in assessing current PCB exposure in demolition work and the utility of wristbands for assessing these exposures.

Multiresidue analysis of bat guano using GC-MS/MS

Bats are the second largest mammalian order and are an endangered species group with a strong need for contamination monitoring. To facilitate non-invasive monitoring of the ecological burden in bat populations, a multiresidue method for the simultaneous quantification of 119 analytes including pesticides, persistent organic pollutants (POPs), active pharmaceutical ingredients (APIs), polycyclic aromatic hydrocarbons (PAHs), UV blockers, plasticizers, and other emerging pollutants in bat guano with gas chromatography tandem mass spectrometry (GC-MS/MS) was developed. Sample preparation and clean-up were performed with a modified QuEChERS approach based on DIN EN 15662. The method uses 1.00 g bat guano as sample with acetonitrile and water for liquid-liquid extraction. Phase separation is assisted by citrate-buffered salting out agent. For clean-up of the extract, primary secondary amine (PSA) was combined with graphitized carbon black (GCB). The lower limits of quantification (LLOQ) ranged between 2.5 and 250 µg kg−1. Linearity was shown in a concentration range from the respective LLOQs to 1250 µg kg−1. The median of the mean recovery was 102.4%. Precision was tested at three concentrations. Method and injection precision were adequate with a relative standard deviation (RSD) below 20%. Furthermore, the comparative analysis with LC-MS/MS demonstrated the reliability of the results and provided a valuable extension of the analytical scope. As proof of concept, three guano samples from a German nursery roost of Myotis myotis were analysed. The results show a time-dependent change in contaminant concentration, highlighting the strong need for non-invasive contamination monitoring of whole bat populations.Graphical

Distribution of 2,2',5,5'-Tetrachlorobiphenyl (PCB52) Metabolites in Adolescent Rats after Acute Nose-Only Inhalation Exposure.

Inhalation of PCB-contaminated air is increasingly recognized as a route for PCB exposure. Because limited information about the disposition of PCBs following inhalation exposure is available, this study investigated the disposition of 2,2',5,5'-tetrachlorobiphenyl (PCB52) and its metabolites in rats following acute, nose-only inhalation of PCB52. Male and female Sprague-Dawley rats (50-58 days of age, 210 ± 27 g; n = 6) were exposed for 4 h by inhalation to approximately 14 or 23 μg/kg body weight of PCB52 using a nose-only exposure system. Sham animals (n = 6) were exposed to filtered lab air. Based on gas chromatography-tandem mass spectrometry (GC-MS/MS), PCB52 was present in adipose, brain, intestinal content, lung, liver, and serum. 2,2',5,5'-Tetrachlorobiphenyl-4-ol (4-OH-PCB52) and one unknown monohydroxylated metabolite were detected in these compartments except for the brain. Liquid chromatography-high resolution mass spectrometry (LC-HRMS) analysis identified several metabolites, including sulfated, methoxylated, and dechlorinated PCB52 metabolites. These metabolites were primarily found in the liver (7 metabolites), lung (9 metabolites), and serum (9 metabolites) due to the short exposure time. These results demonstrate for the first time that complex mixtures of sulfated, methoxylated, and dechlorinated PCB52 metabolites are formed in adolescent rats following PCB52 inhalation, laying the groundwork for future animal studies of the adverse effects of inhaled PCB52.

Metabolomic Analysis of Amino Acid and Organic Acid Profiles in Tissue From Ovarian Cancer Patients Using High-Performance Liquid Chromatography-Tandem Mass Spectrometry (HPLC-MS/MS) and Gas Chromatography-Tandem Mass Spectrometry (GC-MS/MS)

Targeted metabolomics studies on organic acids (OAs) and amino acids (AAs) were performed to search for biomarkers for ovarian cancer progression. Simultaneous AA profiling analysis method was developed through LC-MS/MS. Under optimal conditions, method showed good linearity (r ≥ 0.998) with limits of detection (LOD) ≤ 0.22 ng/mL and limits of quantification (LOQ) of ≤0.72 ng/mL. Repeatability varied from 1.4 to 17.3 relative standard deviation (%RSD) and accuracy varied from −20.6% to 12.1% relative error (% RE). Twenty-six AAs and 13 OAs were detected in the analyses of ovarian tissue from patients with benign ovarian tumors (BOT), borderline tumors (BT), and ovarian serous carcinoma (OSC). Star pattern recognition analysis was performed by normalizing each group to the BOT group. The star symbol plots in the BT and OSC groups were distinct and easily distinguished from those in the BOT group. The BT and the OSC groups exhibited higher 3-hydroxybutyric acid and lactic acid levels, lower pyruvic acid and OA levels in the TCA cycle, and alterations in AA metabolic patterns in comparison to the BOT group. Especially, citrulline and leucine were significantly reduced, while fumaric acid and malic acid significantly increased in the OSC group compared to the BT group. The BT and the OSC groups were completely separated in orthogonal partial least squares-discriminant analysis (OPLS-DA) and heatmap analysis. These findings, elevated ketone body levels, increased anaerobic glycolysis, reduced energy production related to mitochondrial dysfunction in the TCA cycle, and AA metabolic patterns associated with the impaired antioxidant system, may explain the characteristic metabolic reprogramming and Warburg effect related to the progression of the OSC into malignancy.

A three-dimensional hierarchical porous graphene aerogel as a fiber coating for headspace solid-phase microextraction: Enhancing the enrichment and detection of polychlorinated naphthalenes in fish

In this study, a novel three-dimensional hierarchical porous deep eutectic solvents-modified graphene aerogel (3D DES-GA) was synthesized for use as a solid-phase microextraction (SPME) fiber coating. The SPME fiber was characterized by its fluffy and hierarchical porous structure, uniform thickness, and rapid mass transfer capabilities. This fiber demonstrated a lifetime (≥160 uses) and excellent precision (with relative standard deviations of 2.4–6.6% for single fiber and 6.0–9.8% for fiber-to-fiber repeatability). The SPME fiber also exhibited remarkable extraction performance for polycyclic aromatic hydrocarbons and polychlorinated biphenyls, which are common persistent organic pollutants in environmental samples. When combined with gas chromatography-tandem mass spectrometry, the method allowed for high-efficiency extraction (enrichment factors ranging from 1225 to 4652 folds) and sensitive determination (limit of detection ranging from 0.010 to 0.056 pg g−1) of polychlorinated naphthalenes (PCNs) in complex samples. To validate this method, we applied it to the determination of four PCNs in five types of fish tissues. The results revealed the presence of 1-chloronaphthalene at concentrations of 7.0 ± 2.9–34.8 ± 2.1 pg g−1 and 1,4-dichloronaphthalene at concentrations of 6.0 ± 0.3–10.9 ± 1.4 pg g−1 in three fish species. Compared with reported sample pretreatment methods reported in the literature, this proposed headspace SPME method offers additional advantages, including simplicity of operation and reduced sample and organic solvent consumption.