Liquid Chromatography-tandem Mass Spectrometer Research Articles

Unveiling antibiotic contamination in surface water: A study of the Huaihe River Basin's Huaibei Plain, a significant Chinese herbal medicine planting region

The abuse of antibiotics has caused the accumulation of antibiotic residues in environmental media, threatening the ecosystem and human health. Many studies on the distribution of aqueous antibiotics have been reported. However, the pollution status of antibiotics in the environment in Chinese herbal medicine planting areas is rarely comprehensively clarified, resulting in the lack of updated pollution data and conducive suggestions for ecological cultivation and sustainable development of Chinese herbal medicine. Thus, we comprehensively investigated the distribution, profiles, sources, and risks of the antibiotics in the surface water of an important tributary of the Huaihe River Basin, located in Bozhou City, a significant Chinese herbal medicine planting region. Solid-phase extraction coupled with an ultra-performance liquid chromatography-tandem mass spectrometer (SPE-UPLC-MS) was utilized to detect the antibiotics in the water. 27 kinds of antibiotics were identified with total concentrations ranging from 75.01 to 1737.99 ng·L−1, with doxycycline (DC) and doxycycline hydrochloride (DCH) possessed the highest concentration. And DC, DCH, oxilinic acid (OA), sulfamethoxazole (SMZ), clarithromycin (CLA), and roxithromycinum (ROX) were the main antibiotics detected in this basin. Correlation analysis and principal component analysis (PCA) indicated that animal husbandry was the primary source of antibiotics. Furthermore, the ecological risk assessment revealed that certain antibiotics could seriously threaten the survival of aquatic organisms, implying that local Chinese herbal medicines might be at similar growth risk. The drinking risk assessment showed that antibiotics in the water posed low risks for human, and children faced a greater drinking risk than adults. The study can help to facilitate the management of aqueous antibiotic pollution for the ecological cultivation and safe production of Chinese herbal medicine.

Physiological and proteomic characterization revealed the response mechanisms underlying aluminium tolerance in lentil (Lens culinaris Medikus).

Aluminium (Al) toxicity causes major plant distress, affecting root growth, nutrient uptake and, ultimately, agricultural productivity. Lentil, which is a cheap source of vegetarian protein, is recognized to be sensitive to Al toxicity. Therefore, it is important to dissect the physiological and molecular mechanisms of Al tolerance in lentil. To understand the physiological system and proteome composition underlying Al tolerance, two genotypes [L-4602 (Al-tolerant) and BM-4 (Al-sensitive)] were studied at the seedling stage. L-4602 maintained a significantly higher root tolerance index and malate secretion with reduced Al accumulation than BM-4. Also, label-free proteomic analysis using ultra-performance liquid chromatography-tandem mass spectrometer exhibited significant regulation of Al-responsive proteins associated with antioxidants, signal transduction, calcium homeostasis, and regulation of glycolysis in L-4602 as compared to BM-4. Functional annotation suggested that transporter proteins (transmembrane protein, adenosine triphosphate-binding cassette transport-related protein and multi drug resistance protein), antioxidants associated proteins (nicotinamide adenine dinucleotide dependent oxidoreductase, oxidoreductase molybdopterin binding protein & peroxidases), kinases (calmodulin-domain kinase & protein kinase), and carbohydrate metabolism associated proteins (dihydrolipoamide acetyltransferase) were found to be abundant in tolerant genotype providing protection against Al toxicity. Overall, the root proteome uncovered in this study at seedling stage, along with the physiological parameters measured, allow a greater understanding of Al tolerance mechanism in lentil, thereby assisting in future crop improvement programmes.

A metabolic map and artificial intelligence-aided identification of nasopharyngeal carcinoma via a single-cell Raman platform.

Nasopharyngeal carcinoma (NPC) is a complex cancer influenced by various factors. This study explores the use of single-cell Raman spectroscopy as a potential diagnostic tool for investigating biomolecular changes associated with NPC carcinogenesis. Seven NPC cell lines, one immortalised nasopharyngeal epithelial cell line, six nasopharyngeal mucosa tissues and seven NPC tissue samples were analysed by performing confocal Raman spectroscopic measurements and imaging. The single-cell Raman spectral dataset was used to quantify relevant biomolecules and build machine learning classification models. Metabolomic profiles were investigated using ultra-performance liquid chromatography-tandem mass spectrometer (UPLC-MS/MS). By generating a metabolic map of seven NPC cell lines, we identified an interplay of altered metabolic processes involving nucleic acids, amino acids, lipids and sugars. The results from spatially resolved Raman maps and UPLC-MS/MS metabolomics were consistent, revealing an increase of unsaturated fatty acids in cancer cells, particularly in highly metastatic 5-8F and poorly differentiated CNE2 cells. The classification model achieved a nearly perfect classification when identifying NPC and non-NPC cells with an ROC-AUC of 0.99 and a value of 0.97 when identifying 13 tissue samples. This study unveils a complex interplay of metabolic network and highlights the potential roles of unsaturated fatty acids in NPC progression and metastasis. This renders further research to provide deeper insights into NPC pathogenesis, identify new metabolic targets and improve the efficacy of targeted therapies in NPC. Artificial intelligence-aided analysis of single-cell Raman spectra has achieved high accuracies in the classification of both cancer cells and patient tissues, paving the way for a simple, less invasive and accurate diagnostic test.

Monitoring buprenorphine in patients on medication-assisted treatment.

Buprenorphine is used for medication-assisted treatment of opioid dependence. Monitoring of medication adherence involves testing of urine or oral fluid for the drug or its metabolite. Quantitative results using liquid chromatography tandem mass spectrometer testing defined the excretion pattern of the drug and its metabolites. Frequency distribution curves of buprenorphine and norbuprenorphine describe the expected drug concentrations of patients on this medication. Urine and oral fluid drug testing can be used to monitor adherence in this population.

Persistence and recovery of dinotefuran in eastern hemlock (Tsuga canadensis) foliage and twigs by UPLC-MS/MS and ELISA.

Dinotefuran, a systemic neonicotinoid insecticide, is approved for control of hemlock woolly adelgid (HWA) (Adelges tsugae Annand), an invasive sap-feeding insect that can kill eastern hemlocks (Tsuga canadensis). Dinotefuran is highly water soluble, facilitating more rapid translocation and HWA control than other neonicotinoids, but its persistence is not well-known. Samples of needles and twigs were collected in spring 2021 from 50 hemlocks treated with a dinotefuran basal trunk spray in 2018 or 2019 (131-145 weeks and 85-93 weeks before sampling, respectively). Processed samples were analyzed with ultra-performance liquid chromatography-tandem mass spectrometer (UPLC-MS/MS) and enzyme-linked immunosorbent assays (ELISA). Dinotefuran residues were 4.6-6.1 times higher in needles than in twigs collected from the same trees. Average (±SE) residues in foliage samples collected from trees treated in 2019 ranged from 0.663 ± 0.243 to 0.564 ± 0.119 mg kg-1 , compared with 0.213 ± 0.033 and 0.225 ± 0.132 mg kg-1 in foliage from trees treated in 2018. Foliage residues from UPLC-MS/MS were consistently lower but strongly related to those from ELISA. Matrix effects appeared to disrupt ELISA analysis of twigs. None of the 25 trees treated in 2019 had live HWA when samples were collected in 2021 while low densities of HWA were observed on 52% of trees treated in 2018. Dinotefuran was recovered from hemlock foliage, and to a lesser extent twigs, >2 years post-treatment. This, along with its relatively rapid translocation, suggests dinotefuran is a viable option for protecting declining or heavily infested hemlocks from HWA. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Fate characteristics and risk identification of thifluzamide in buckwheat across China: Analytical method development, occurrence, and health assessment

Elaborating on the fate tendency of thifluzamide (thiazole-amide fungicide) in buckwheat based on nationwide application is vital for grain security and human health based on nationwide application. A rapid and sensitive analytical method was developed to trace thifluzamide in buckwheat matrices using an ultrahigh-performance liquid chromatography-tandem triple quadrupole mass spectrometer (UHPLC-MS/MS), with a retention time of 2.90 min and limit of quantitation (LOQ) of 0.001 mg/kg. Thifluzamide could be stably stored for 84 d in buckwheat matrices under –20 °C under dark condition. The occurrence, dissipation and terminal magnitudes of thifluzamide were reflected by the primary deposition of 0.02–0.55 mg/kg, half-lives of 12–14 d, and highest residues of 0.41 mg/kg. The long-term risks (ADI%) of thifluzamide were 37.268 %–131.658 % in registered crops, and the risks for the rural population were significantly higher than those of the urban population. The unacceptable dietary risks of thifluzamide should be continuously emphasized for children aged 2–7 with an ADI% values of 100.750 %–131.658 %. A probabilistic model was further introduced to evaluate the risk discrepancy of thifluzamide in buckwheat, showing the risks in Tartary buckwheat (Fagopyrum tararicum Gaerth) were 1.5–75.4 times than that in sweet buckwheat (Fagopyrum esculentum Moench). Despite the low risks for dietary buckwheat, the high-potential health hazards of thifluzamide should be pay more attention given the increasing applications and cumulative effects.

Poly- and per-fluoroalkyl substances in water: Occurrence, analytical methodologies, and remediations strategies: A comprehensive review

Abstract Poly- and perfluoroalkyl substances (PFASs) are fluoro-organic compounds comprising thousands of anthropogenically produced chemicals with various industrial and consumer applications. This review compiles recent information on the sources, occurrence, and health effects of PFAS in aquatic environments. Secondly, as a primary requirement for assessing the PFAS concentration in water, this review systematically summarised the analytical methodologies (sample preparation and analytical detection techniques) for PFAS. Furthermore, health risks associated with PFAS in water are outlined. Finally, researchers worldwide have investigated the strategies for the remediation and elimination of PFAS from water. Previous studies have shown that PFASs are present in various water bodies with the highest concentration detected in Germany (94–4,385 ng·L−1 in river and drinking waters). The findings of this review further revealed that solid-phase extraction techniques were the most preferred for sample preparation compared to liquid–liquid extraction techniques. Solid-phase extraction technique improved the limit of detection and the limit of quantification of many analytical techniques to 0.010–1.15 and 0.030–4.00 ng·L−1, respectively. For PFAS remediation, the adsorption method and chemical oxidation using heat-activated persulfate and photochemical oxidation were the most used techniques. The most studied water matrices were drinking, river, groundwater, wastewater, and modelled ultra-pure water. The most used detection technique was found to be liquid chromatograph-tandem mass spectrometer (LC-MS/MS).

Urinary concentrations and elimination half-lives of parabens, benzophenones, bisphenol and triclosan in Japanese young adults.

Environmental phenols are widely distributed in the environment and human samples, suggesting potential exposure to these chemicals. We designed an intervention trial with 30 participants over 6 days to assess the urinary concentrations and half-lives of environmental phenols in Japanese young people. The target environmental phenols include three parabens (methyl paraben, ethyl paraben, and propyl paraben), two benzophenones (benzophenone 1 and 3), two bisphenols (bisphenol F and bisphenol S), and triclosan. Throughout the intervention, the participants consumed the same food and drinks and used personal care products provided by the project. The target phenols were measured in urine from the participants using a liquid chromatography-tandem mass spectrometer. We compared the measured concentrations between the study periods to better understand the exposure tendency. Some statistically significant differences were observed. All target analytes were detected in more than 50% of samples collected on Day 0 (the day before the intervention). Methyl paraben was the dominant phenol detected in urine (1640 μg/g-creatinine), followed by ethyl paraben (119 μg/g-creatinine). Downward trends in creatinine-corrected concentrations were observed for all target analytes in some instances. Non-compartment analysis was performed to estimate urinary excretion parameters. The estimated half-lives ranged from 7.69 to 20.3 h. Use of paraben-free products during the intervention period reduced the body burden.

Changes in the Biological Activities of Gracilaria verrucosa Extracted Using Different Extraction Solvents

This study investigated the antioxidant, antiaging, and antibacterial properties of Gracilaria verrucosa (GV) based on 95% methanol (GVM), ethanol (GVE), and hot water (GVW) extractions. Antioxidant activity assays revealed the total polyphenol and flavonoid contents were highest in GVM and GVE. The 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) and 2,2′-Azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) activities were highest in GVE and GVM. Furthermore, GVE exhibited the highest ferric-reducing antioxidant power (FRAP) value. In comparison, superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) activities were highest in GVM. Collectively, GVE and GVM had stronger antioxidant activities than GVW. Additionally, collagenase, elastase, and tyrosinase inhibition assays showed that GVM exhibited the strongest anti-wrinkle and skin-whitening activities. Liquid chromatography–tandem mass spectrometer (LC–MS/MS) revealed that GVW had the highest 4-hydroxy benzoic acid content, whereas GVE had the highest naringenin and naringin contents. Additionally, GVE exhibited the strongest antimicrobial activity against six foodborne bacteria, with minimum inhibitory and bactericidal concentrations of 0.06–0.3 and 0.1–0.5 μg/μL. Correlation analysis of the GV extracts indicated a strong positive relationship between TPC and ABTS, SOD, and CAT activities (r = 0.760–0.982, p = 0–0.018). Overall, GVE and GVM can be applied to the development of functional agents across diverse industries.

Relationship between vitamin D and parathyroid hormone in Chinese elderly people

To explore the relationship between serum 25-hydroxyvitamin D(25(OH)D) and serum parathyroid hormone(PTH) level in Chinese people aged 50 years and above, and to probe the optimum threshold for vitamin D sufficiency preliminarily, and apply this threshold to predict the risk of metabolic syndrome(Mets) in this population. A total of 750 serum samples were selected from the biological samples' bank of Chinese Chronic Diseases and Nutritional Survey(CCDNS, 2015-2017) by stratified sampling, basic information(including age, gender, season, etc. ) were collected from questionnaire and physical measurement of the subjects were conducted unified. Serum 25(OH)D concentration was determined by high performance liquid chromatography tandem mass spectrometer, and PTH and interleukin-6(IL-6) were detected by electrochemiluminescence method. Phosphorus, albumin(Alb), creatinine(Cr) in blood were detected by automatic biochemical analyzer. Factors affecting the concentration of 25(OH)D and PTH were found by multiple linear regression and adjusted by generalized additive model separately, threshold was predicted by locally weighted regression and smoothing scatterplot, abbreviated as LOESS, and the exact threshold of 25(OH)D was found when PTH reached the plateau by nonlinear least squares estimation and segmented regression. Relationship between 25(OH)D and Mets was analyzed by multivariate logistic regression using the different cut-off points in Chinese elderly people. Reference threshold for vitamin D deficiency in Chinese elderly people can be preliminarily discovered as serum total 25(OH)D was 19.62 ng/mL, and 28.44 ng/mL can be used as reference threshold for sufficient vitamin D. Sufficient 25(OH)D(≥28.44 ng/mL) could reduce the risk of Mets significantly(OR=0.617(0.439-0.869)) after adjusting for confounding factors such as sex, age, region, season, ect. A plateau in PTH was observed at a 25(OH)D concentration of 20.03-28.43 ng/mL for male whereas 13.12-26.33 ng/mL for female by gender stratification analysis, but no cut-off point was obtained statistically. Reference threshold for vitamin D sufficiency in Chinese elderly people was preliminarily observed in the range of 19.62-28.44 ng/mL when PTH was maximally inhibited, and the threshold may vary with gender. Applying the threshold we also found that more sufficient levels of vitamin D were protective against Mets in this population.

Preparation of arginine-loaded mesoporous silica nanoparticles (Arg@MSNs) to improve the mechanical and antibacterial properties of denture base resin

Whether the incorporation of arginine-loaded mesoporous silica nanoparticles (Arg@MSNs) into denture base resin can improve the mechanical and antibacterial properties is unclear. The purpose of this in vitro study was to synthesis Arg@MSNs and explore how Arg@MSNs incorporation affects the mechanical and antibacterial properties of denture base resin. Arg@MSNs were synthesized via a sol-gel process and characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS), and X-ray diffraction (XRD). The prepared Arg@MSNs at different weight ratio concentrations were added into denture base resin as the experimental group, and unmodified denture base resin was the control. The fracture surface and arginine release behavior of each specimen were detected using scanning electron microscopy (SEM) and ultra-high-performance liquid chromatography-tandem mass spectrometer (UHPLC-HESI-MS/MS), respectively. Three-point bend tests were applied using a universal testing machine for evaluation of the mechanical properties of each group (n=5). Antibacterial efficiency (n=3) was evaluated by both quantitative and qualitative analysis using Streptococcus mutans. The cytotoxic effect of the Arg@MSN-modified denture base resin was investigated using a cell counting kit (CCK)-8 test. Data were subjected to 1-way analysis of variance followed by the post hoc Tukey honestly significant difference test (ɑ=.05). The prepared Arg@MSNs had good monodispersity and spherical morphology. Arg@MSN concentration at 0.5wt%, 1wt%, and 2.5wt% resulted in enhanced mechanical properties, while those at 5wt% were adversely impacted. Biofilm pH values increased with the incorporation of Arg@MSNs, and the antibacterial performance was improved. The CCK-8 test revealed that all formulations were not cytotoxic. The addition of Arg@MSNs into denture base resin can enhance its mechanical properties and improve its antibacterial performance without any apparent cytotoxic effect.

Cysteamine ophthalmic hydrogel for the treatment of ocular cystinosis

Ocular cystinosis is a rare disease characterised by the deposition on the corneal surface of cystine crystals that hinder the eyesight of patients. Oral cysteamine is administered as cysteamine bitartrate; however, due to the lack of corneal vascularization it does not reach the cornea and must be administered by the topical ocular route. The aim of the present study was to determine the stability of an ophthalmic hydrogel of cysteamine under different preservation conditions during a follow-up of 30 days. This hydrogel could be prepared in hospital pharmacy services.Several physical and chemical parameters were assessed: osmolality, pH, and cysteamine concentration, which was measured using an ultra-performance liquid chromatography-tandem mass spectrometer (UPLC-MS/MS) method. Descriptive tests were also performed, such as transparency measurements and microbiological assays in order to verify sterility. The results show that cysteamine hydrogel is stable over 30 days and should be preserved under refrigeration.

Uncovering proteome variations and concomitant quality changes of differently drying-treated rape (Brassica napus) bee pollen by label-free quantitative proteomics

High moisture content of fresh bee pollen makes it difficult to preserve and thus makes drying a necessary process during the bee pollen production. Drying treatment will affect its quality and the effects of sun drying, hot-air drying and freeze drying on the proteome of rape (Brassica napus) bee pollen have been evaluated using label-free quantitative proteomics by liquid chromatography-tandem mass spectrometer (LC-MS/MS). A total of 8377 proteins are identified, among which the most abundant differential proteins were found in freeze drying-treated samples. Also freeze-drying treatment maximizes the content of antioxidant, antibacterial and anemic bioactive pollen protein. Besides, rape bee pollen is found to adjust its metabolism to protect itself during the drying process. These results can be favorable to evaluate the effects of drying treatment on the nutrition and function of processed rape bee pollen and insight into how rape bee pollen proteins respond to dehydration.

Mid-dosing interval concentration is important for polymyxin B exposure and acute kidney injury in critically ill patients.

This study aimed to evaluate the association between polymyxin B (PMB) exposure and acute kidney injury (AKI) and analyze the risk factors for PMB-induced AKI in critically ill patients. Plasma concentrations of PMB were determined using an ultra-performance liquid chromatography-tandem mass spectrometer in intensive care unit patients who were administered PMB. Univariate and multivariate analyses were conducted to identify risk factors. A receiver operating characteristic curve was constructed to assess the discriminant power of the factors and to identify the cut-off value for AKI. The white blood cell count and estimated area under the concentration-time curve (AUC) of patients administered PMB were independent risk factors for PMB-induced AKI, where AUC were calculated using a first-order pharmacokinetic equation based on the mid-dosing interval concentration (C1/2t ) and peak concentration. The area under the receiver operating characteristic curve of the final model was 0.805 (95% confidence interval 0.690-0.921). The cut-off value for the combined predictor was 0.57. Alternatively, when using C1/2t , which was strongly correlated with AUC, as the only independent risk factor, the analysis showed that the 3.47 μg/mL threshold provides favorable differentiation between the AKI and non-AKI groups. These results provide insightful information for TDM-guiding PMB dosing in the clinical practice.

Evaluation of the Long-Term Stability of Select Phenylacetylindole, Cycloalkylindole, Quinolinyl, and Carboxamide Synthetic Cannabinoids using LC-MS/MS.

Forensic toxicology laboratories often encounter casework backlogs, which raise concerns for drug stability that can be affected by long storage times, temperature, and preservatives, or the lack thereof. The focus of this research was to evaluate the impact of these factors on the stability of 17 synthetic cannabinoids in human whole blood and 10 associated metabolites in human urine. The fortified biological specimens were stored under room temperature (20°C), refrigerator (4°C), and freezer (-20°C) conditions for a period of 52 weeks. Preservatives included potassium oxalate, sodium ethylenediaminetetraacetic acid, and sodium fluoride. Extraction of analytes was conducted using supported liquid extraction and analyzed using a liquid chromatograph-tandem mass spectrometer. Under all three storage conditions, the majority of urine metabolites were stable up to 9 weeks. All analytes in frozen sodium fluoride preserved blood were stable at 21 to 52 weeks with the exception of APP-PICA. Analytes in blood that were stable to 52 weeks in the freezer generally had a core structure of a carbonyl substituent on a pyrazole or pyrrole with surrounding nonpolar groups. In contrast, compounds with two adjacent polar carbonyl functional groups experienced degradation at 1 week or less under ambient temperature and refrigeration. 5-fluoropentyl analogs, XLR11 and 5-fluoro ADB-PINACA, in comparison to their counterpart analytes, UR144 and ADB-PINACA, were unstable at earlier time points under all temperatures. Based on these data, forensic blood evidence suggesting the presence of synthetic cannabinoid compounds are recommended to be frozen with sodium fluoride and potassium oxalate preservatives for optimal quantitative results.

The effect of anthocyanin from Dioscorea alata L. after purification, identification on antioxidant capacity in mice.

Increasing findings devote to searching for natural active compositions as additives to ameliorate health status. Anthocyanin, water-soluble natural pigment, has been concerned due to its favorable antioxidant activity. In this study, we purified anthocyanin from Dioscorea alata L., identified its compounds, and evaluated its antioxidant properties. The results indicated that the purity of anthocyanin increased to 39.59 ± 1.56%, 60.18 ± 1.97%, and 81.08 ± 1.97% after purification via AB-8 macroporous resin, Sep-Pak C18 solid phase, and LH-20 Sephadex stepwise. Ultra-performance liquid chromatography tandem mass spectrometer results indicated that paeoniflorin-3,5-O-dihexoside, petunin-3-O-feruloyl-glucoside-5-O-glucoside, cyanidin-3-O-feruloyl glucoside-5-O-glucoside, cyanidin-3-O-sophoroside, and petunin-3,5-O-dihexoside were the major compounds. The purified anthocyanin exhibited stronger antioxidant activity than the unpurified extract and ascorbic acid, whereas weaker than that of cyanidin-3-O-glucoside in general, which was assessed using DPPH, ABTS, and Fe3+ reducing capacity methods. Moreover, the purified anthocyanin increased GSH-Px, total antioxidant capacity, and superoxide dismutase activities and decreased malondialdehyde concentration on serum in mice after administering lipopolysaccharide for 24 h (p < .05). To summarize, the purified anthocyanin boasts more outstanding antioxidant properties than that of crude extracts. These results provide a reference with source of anthocyanin and it is conducive to use Dioscorea alata L. resources.

Research Note: Diethylstilbestrol reduces primordial germ cells in male Japanese quail

This study investigated the detrimental effects of diethylstilbestrol (DES), an estrogenic endocrine-disrupting chemical, on the viability of primordial germ cells (PGCs), embryonic precursors of germ cells, in Japanese quail. We injected 50 or 100 nmol DES solubilized in sesame oil into the yolk of stage X embryos and assessed changes in the population and cell cycle properties of circulating PGCs in blood vessels and gonadal PGCs after 2.5- and 7-day incubations, respectively. Liquid chromatography tandem mass spectrometer and Western blotting analyses identified DEAD-box polypeptide 4 (DDX4) and proliferating cell nuclear antigen (PCNA) as a stem cell marker and proliferation marker of quail PGCs, respectively. Immunochemical analyses revealed significant decreases in the number of DDX4- and PCNA-positive blood-circulating PGCs in males treated with 50 and 100 nmol DES than in the oil-treated control group. These reductions were not observed in females. Furthermore, the number of DDX4-positive gonadal PGCs was smaller in males treated with 50 and 100 nmol DES than in the control group, and these reductions were not observed in females. The protein expression of the Sertoli cell marker showed normal testis development in DES-treated embryos on d 7. These results demonstrate the potentially cytotoxic effects of DES on male germ cells, namely, the inhibition of cell cycle progression and induction of apoptosis in Japanese quail.

Sequestration of Mecoprop herbicide from water using XAD-4 resin impregnated with Aliquat 336 and quantification with Liquid Chromatography-Tandem mass spectrometer (LC-MS/MS)

ABSTRACT Amberlite-XAD 4 resin was modified with ionic liquid (Aliquat-336) for adsorptive removal of Methylchlorophenoxy propionic acid (MCPP). The modification of resin with ionic liquid improved the adsorption of MCPP on Amberlite resin. The modified resin was mesoporous with a high surface area of 418.7 m2 g−1 confirmed by BET-N2 isotherm studies. The functional modification and mechanistic features of the modified resin adsorbent were studied using different techniques such as SEM-EDX, TGA, PXRD, XRF, FT-IR, and XPS. The adsorption capacity of the material 64.7 mg g−1 following pseudo-second-order kinetics. The thermodynamic studies affirmed spontaneity and endothermic adsorption. The reusability of the material was up to three cycles. The modified resin could remove 86% of MCPP in run-off water.

Quantification of Biologically Active DNA Alkylation in Temozolomide-Exposed Glioblastoma Cell Lines by Ultra-Performance Liquid Chromatography-Tandem Mass Spectrometry: Method Development and Recommendations for Validation.

Quantitative monitoring of biologically active methylations of guanines in samples exposed to temozolomide (TMZ) would be useful in glioblastoma research for preclinical TMZ experiments, for clinical pharmacology questions regarding appropriate exposure, and ultimately for precision oncology. The known biologically active alkylation of DNA induced by TMZ takes place on O6 position of guanines. However, when developing mass spectrometric (MS) assays, the possible signal overlap of O6-methyl-2'-deoxyguanosine (O6-m2dGO) with other methylated 2'-deoxyguanosine species in DNA and methylated guanosines in RNA must be considered. Liquid chromatography-tandem MS (LC-MS/MS) offers the analytical requirements for such assays in terms of specificity and sensitivity, especially when multiple reaction monitoring (MRM) is available. In preclinical research, cancer cell lines are still the gold standard model for in vitro drug screening. Here, we present the development of ultra-performance LC-MRM-MS assays for the quantification of O6-m2dGO in a TMZ-treated glioblastoma cell line. Furthermore, we propose adapted parameters for method validation relevant to the quantification of drug-induced DNA modifications.

Validation and Application of UPLC-MS/MS Method to Analysis of Glyphosate and its Metabolites in Water.

A method was developed to determine glyphosate and their metabolites in water. The widespread use of this herbicide in agricultural activities worldwide, despite the reported adverse effects on both the environment and health, is a cause for concern and makes it necessary to monitor its presence through a method that guarantees the determination at trace levels. A direct extraction of the analytes with phosphate buffer was performed with subsequent derivatization with 9-fluorenylmethyl chloroformate. The quantification was determined by Ultra Performance Liquid Chromatography-tandem mass spectrometer. The method was validated through the following parameters: selectivity, detection and quantification limits, linearity, accuracy, precision and uncertainty. The average recoveries ranged between 94.08 and 103.31%. Additionally, detection limits from 0.396 to 0.433μg/L, and the quantification limit was 5.0μg/L for all the analytes evaluated. In terms of linearity and precision, the results obtained were in the ranges considered adequate (R2 ≥ 0.99 and CV ≤ 20%), the estimated expanded uncertainty was 12.95, 11.15 and 13.83% for glyphosate, aminomethylphosphonic acid and glufosinate, respectively. This method was successfully applied for the determination of the target analytes in irrigation water samples, detecting concentrations of aminomethylphosphonic acid over limit detection for some sampling sites.