Ultra-high Performance Liquid Chromatography-tandem Mass Research Articles

Quantitation of Canadian organic ultraviolet filters using polarity switching and ultra-high performance liquid chromatography-tandem mass spectrometry

Ultraviolet filters (UVFs) absorb UV light and are comprised of numerous classes of compounds including inorganic and organic. They have been used for decades in protecting humans from skin damage and cancer. Recent studies have shown that UVFs are found in many phases of abiotic and biotic systems with their physical-chemical characteristics determining environmental fate and potential biological impacts such as bioaccumulation. This study developed a unified method to quantify eight UVFs (avobenzone, dioxybenzone, homosalate, octinoxate, octisalate, octocrylene, oxybenzone, and sulisobenzone) by solid phase extraction and ultra-high performance liquid chromatography-tandem mass spectrometry using polarity switching. The validated method resulted in accuracies ranging from 75 to 112%, MLD/MLQs of 0.00015/ 0.00049 to 0.0020/ 0.0067 ng mL−1, and precisions of 1.8 to 22.6% (intraday) and 1.3 to 17.2% (interday). The method was applied to chlorinated outdoor pool waters in the City of Winnipeg, Manitoba, Canada. This method could be adapted for a variety of chlorinated and unchlorinated waters such as drinking water, wastewater, and surface waters.

Metabolomic and transcriptomic analyses of Fmo5-/- mice reveal roles for flavin-containing monooxygenase 5 (FMO5) in NRF2-mediated oxidative stress response, unfolded protein response, lipid homeostasis, and carbohydrate and one-carbon metabolism.

Flavin-containing monooxygenase 5 (FMO5) is a member of the FMO family of proteins, best known for their roles in the detoxification of foreign chemicals and, more recently, in endogenous metabolism. We have previously shown that Fmo5-/- mice display an age-related lean phenotype, with much reduced weight gain from 20 weeks of age. The phenotype is characterized by decreased fat deposition, lower plasma concentrations of glucose, insulin and cholesterol, higher glucose tolerance and insulin sensitivity, and resistance to diet-induced obesity. In the present study we report the use of metabolomic and transcriptomic analyses of livers of Fmo5-/- and wild-type mice to identify factors underlying the lean phenotype of Fmo5-/- mice and gain insights into the function of FMO5. Metabolomics was performed by the Metabolon platform, utilising ultrahigh performance liquid chromatography-tandem mass spectroscopy. Transcriptomics was performed by RNA-Seq and results analysed by DESeq2. Disruption of the Fmo5 gene has wide-ranging effects on the abundance of metabolites and expression of genes in the liver. Metabolites whose concentration differed between Fmo5-/- and wild-type mice include several saturated and monounsaturated fatty acids, complex lipids, amino acids, one-carbon intermediates and ADP-ribose. Among the genes most significantly and/or highly differentially expressed are Apoa4, Cd36, Fitm1, Hspa5, Hyou1, Ide, Me1 and Mme. The results reveal that FMO5 is involved in upregulating the NRF2-mediated oxidative stress response, the unfolded protein response and response to hypoxia and cellular stress, indicating a role for the enzyme in adaptation to oxidative and metabolic stress. FMO5 also plays a role in stimulating a wide range of metabolic pathways and processes, particularly ones involved in lipid homeostasis, the uptake and metabolism of glucose, the generation of cytosolic NADPH, and in one-carbon metabolism. The results predict that FMO5 acts by stimulating the NRF2, XBP1, PPARA and PPARG regulatory pathways, while inhibiting STAT1 and IRF7 pathways.

Development and validation of an ultrahigh-performance liquid chromatography-tandem mass spectrometry method to investigate the plasma pharmacokinetics of a KCa 2.2/KCa 2.3 positive allosteric modulator in mice.

There is currently no treatment for spinocerebellar ataxias (SCAs), which are a group of genetic disorders that often cause a lack of coordination, difficulty walking, slurred speech, tremors, and eventually death. Activation of KCa 2.2/KCa 2.3 channels reportedly exerts beneficial effects in SCAs. Here, we report the development and validation of an analytical method for quantitating a recently developed positive allosteric modulator of KCa 2.2/KCa 2.3 channels (compound 2q) in mouse plasma. Mouse plasma samples (10 μL) containing various concentrations of 2q were subjected to protein precipitation in the presence of a structurally similar internal standard (IS). Subsequently, the analytes were separated on a C18 ultrahigh-performance liquid chromatography column and detected by a tandem mass spectrometer. The method was validated using US Food and Drug Administration (FDA) guidelines. Finally, the validated assay was applied to the measurement of the plasma concentrations of 2q in plasma samples taken from mice after single intravenous doses of 2mg/kg of 2q, and the pharmacokinetic parameters of 2q were determined. The calibration standards were linear (r2 ≥ 0.99) in the range of 1.56-200 nM of 2q with intra- and inter-run accuracy and precision values within the FDA guidelines. The lower limit of quantitation of the assay was 1.56 nM (0.258 pg on the column). The recoveries of 2q and IS from plasma were >94%, with no appreciable matrix effect. The assay showed no significant carryover, and the plasma samples stored at -80°C or the processed samples stored in the autosampler at 10°C were stable for at least 3 weeks and 36 h, respectively. After intravenous injection, 2q showed a bi-exponential decline pattern in the mouse plasma, with a clearance of 30 mL/min/kg, a terminal volume of distribution of 1.93 mL/kg, and a terminal half-life of 45 min. The developed assay is suitable for preclinical pharmacokinetic-pharmacodynamic studies of 2q as a potential drug candidate for ataxias.

A retrospective screening method for carbamate toxicant exposure based on butyrylcholinesterase adducts in human plasma with ultra-high performance liquid chromatography–tandem mass spectrometry

Carbamate pesticides are extensively used in agriculture for their inhibition to acetylcholinesterase and damages to the insects’ neural systems. Because of their toxicity, human poisoning incidents caused by carbamate pesticide exposure have occurred from time to time. What’s more, some lethally toxic carbamate toxicants known as carbamate nerve agents (CMNAs) have been supplemented in Schedule 1 of the Annex on Chemicals in the Chemical Weapons Convention (CWC) by Organisation of the Prohibition of Chemical Weapons (OPCW) from 2020. And some other carbamates, like physostigmine, have been used in clinical treatment as anticholinergic drugs and their misuse may also cause damages to the body. Similar to organophosphorus toxicants, carbamate toxicants would react with butyrylcholinesterase (BChE) in plasma when entering the human body, resulting in the BChE adducts, based on which the exposure of carbamate toxicants could be detected retrospectively. In this study, methylcarbamyl nonapeptide and dimethylcarbamyl nonapeptide from pepsin digestion of BChE adducts were identified with ultra-high performance liquid chromatography–tandem mass spectrometry (UHPLC–MS/MS) in product ion scan mode. Carbofuran was chosen as the target to establish the detection method of carbamate toxicant exposure based on methylcarbamyl nonapeptide digested from methylcarbamyl BChE. Procainamide-gel affinity purification, pepsin digestion and UHPLC–MS/MS analysis in multiple reaction monitoring (MRM) mode were applied. Under the optimized conditions of sample preparation and UHPLC–MS/MS MRM analysis, the limits of detection (LODs) reached 10.0 ng/mL of plasma exposed to carbofuran with satisfactory specificity. The quantitation approach was established with d3-carbofuran-exposed plasma as the internal standard (IS) and the linearity range was 30.0–1.00 × 103 nmol/L (R2 >0.998) with the accuracy of 95.6%–107% and precision of ≤9% relative standard deviation (RSD). The applicability was also evaluated by N,N-dimethyl-carbamates with the LODs of 30.0 nmol/L for pirimicarb-exposed plasma based on dimethylcarbamyl nonapeptide. Because most of carbamate toxicants has methylcarbamyl or dimethylcarbamyl groups, this approach could be applied on the retrospective screening of carbamate toxicant exposure including CMNAs, carbamate pesticides or carbamate drugs. This study could provide an effective means in the fields of CWC verification, toxicological mechanism investigation and down-selection of potential treatment options.

The role of metabolic perturbations in mediating the effects of ambient air pollution on lung cancer in the cancer prevention studies.

10541 Background: Exposure to ambient air pollution is an established risk factor for lung cancer. Investigation on the underlying mechanisms of air pollution carcinogenicity remains challenging due to the complex composition of air pollution and a lack of sensitive biomarkers to accurately measure exposure and corresponding response. To address the knowledge gaps, we applied high-resolution metabolomics to identify metabolic signatures of exogenous air pollution exposures and endogenous processes involved in lung carcinogenesis. Methods: A total of 683 matched lung cancer and control pairs within the established Cancer Prevention Study-II (CPS-II) Nutrition and CPS-3 cohorts were included in this study. The plasma metabolome was profiled with ultrahigh-performance liquid chromatography-tandem mass spectrometry. Assessment of exposure to six ambient air pollutants, including carbon monoxide (CO), nitrogen dioxide (NO2), particulate matter (PM10), fine particulate matter (PM2.5), sulfur dioxide (SO2), and ozone (O3), was conducted using spatiotemporally-resolved models based on residential address at blood draw and calculated based on yearly average levels. We conducted metabolome-wide association studies with multiple linear regression models to assess associations of ambient air pollution and lung cancer with a meet-in-the-middle approach. Models controlled for potential confounders and covariates including age at blood draw, sex, race, body mass index, alcohol consumption, smoking status, passive smoke exposure, vegetable and fruit intake, and educational level. Metabolites significant at the FDR < 0.2 level in the air pollution model were analyzed in the lung cancer model. High-dimensional mediation analysis was used as a secondary analysis to compare results from the meet-in-the-middle analysis. Results: Among 1,204 metabolic features extracted from the blood samples, seven features were significantly associated with air pollution exposure and lung cancer incidence at the FDR < 0.2 level in the meet-in-the-middle analysis. Six features were significant at the p < 0.01 level through high-dimensional mediation analysis. All confirmed metabolites are enriched within peptide, lipid, and amino acid pathways. Gamma-glutamylglutamine and gamma-glutamylmethionine were statistically significantly associated with CO, NO2, and PM10 exposure and lung cancer incidence in both analyses. Conclusions: This is the largest prospective metabolomics study examining biological perturbations associated with air pollution exposure and lung cancer incidence. Peptide metabolism may play an important role in mediating the association between air pollution and lung cancer. Findings from this study will lay the foundation for future studies to further understand the biological mechanisms underlying the carcinogenicity of air pollution.

Biotransformation and brain distribution of the anti-COVID-19 drug molnupiravir and herb-drug pharmacokinetic interactions between the herbal extract Scutellaria formula-NRICM101

The aim of this study was to explore the effects of herbal drug pharmacokinetic interactions on the biotransformation of molnupiravir and its metabolite β-D-N4-hydroxycytidine (NHC) in the blood and brain. To investigate the biotransformation mechanism, a carboxylesterase inhibitor, bis(4-nitrophenyl)phosphate (BNPP), was administered. Not only molnupiravir but also the herbal medicine Scutellaria formula-NRICM101 is potentially affected by coadministration with molnupiravir. However, the herb-drug interaction between molnupiravir and the Scutellaria formula-NRICM101 has not yet been investigated. We hypothesized that the complex bioactive herbal ingredients in the extract of the Scutellaria formula-NRICM101, the biotransformation and penetration of the bloodbrain barrier of molnupiravir are altered by inhibition of carboxylesterase. To monitor the analytes, ultrahigh-performance liquid chromatography tandem mass spectrometry (UHPLCMS/MS) coupled with the microdialysis method was developed. Based on the dose transfer from humans to rats, a dose of molnupiravir (100 mg/kg, i.v.), molnupiravir (100 mg/kg, i.v.) + BNPP (50 mg/kg, i.v.), and molnupiravir (100 mg/kg, i.v.) + the Scutellaria formula-NRICM101 extract (1.27 g/kg, per day, for 5 consecutive days) were administered. The results showed that molnupiravir was rapidly metabolized to NHC and penetrated into the brain striatum. However, when concomitant with BNPP, NHC was suppressed, and molnupiravir was enhanced. The blood-to-brain penetration ratios were 2% and 6%, respectively. In summary, the extract of the Scutellaria formula-NRICM101 provides a pharmacological effect similar to that of the carboxylesterase inhibitor to suppress NHC in the blood, and the brain penetration ratio was increased, but the concentration is also higher than the effective concentration in the blood and brain.

Signal-On Mass Spectrometric Biosensing of Multiplex Matrix Metalloproteinases with a Phospholipid-Structured Mass-Encoded Microplate.

The detection of matrix metalloproteinases (MMPs) is of great importance for diagnosis and staging of cancer. This work proposed a signal-on mass spectrometric biosensing strategy with a phospholipid-structured mass-encoded microplate for assessment of multiplex MMP activities. The designed substrate and internal standard peptides were subsequently labeled with the reagents of isobaric tags for relative and absolute quantification (iTRAQ), and DSPE-PEG(2000)maleimide was embedded on the surface of a 96-well glass bottom plate to fabricate the phospholipid-structured mass-encoded microplate, which offered a simulated environment of the extracellular space for enzyme reactions between MMPs and the substrates. The strategy achieved multiplex MMP activity assays by dropping the sample in the well for enzyme cleavages, followed by adding trypsin to release the coding regions for ultrahigh performance liquid chromatography-tandem mass spectrometric (UHPLC-MS/MS) analysis. The peak area ratios of released coding regions and their respective internal standard (IS) peptides exhibited satisfied linear ranges of 0.05-50, 0.1-250, and 0.1-100 ng mL-1 with the detection limits of 0.017, 0.046, and 0.032 ng mL-1 for MMP-2, MMP-7, and MMP-3, respectively. The proposed strategy demonstrated good practicability in inhibition analysis and detections of multiplex MMP activities in serum samples. It is of great potential for clinical applications and can be expanded for multiplex enzyme assays.

Rapid microwave synthesis of MOF microrods: Dispersive SPE coupled with UHPLC–MS/MS to determine fluoroquinolones in honey

A novel sorbent Cu–S metal–organic framework (MOF) microrods was prepared for dispersive solid-phase extraction via microwave synthesis and used to determine 12 fluoroquinolones (FQs) in honey samples employing ultrahigh-performance liquid chromatography–tandem mass spectrometry (UHPLC–MS/MS). The best extraction efficiency was achieved by optimizing sample pH, sorbent quantity, eluent type/volume, and extraction and elution time. The proposed MOF exhibits advantages such as rapid synthesis time (20 min) and outstanding adsorption ability toward zwitterionic FQs. These advantages can be attributed to multiple interactions, including hydrogen bonding, π–π interaction, and hydrophobic interaction. The limits of detection of analytes were 0.005–0.045 ng g−1. Acceptable recoveries (79.3%–95.6%) were obtained under the optimal conditions. Precision (relative standard deviation, RSD) was <9.2%. These results demonstrate the utility of our sample preparation method and the high capacity of Cu–S MOF microrods for rapid and selective extraction of FQs from honey samples.

Toward High-Throughput Analysis of Aroma Compounds Using Ultrahigh-Performance Liquid Chromatography-Tandem Mass Spectrometry: Screening of Key Food Odorants in Various Foods.

Recent studies show the immense capacities of the unified quantitation of aroma and taste compounds using liquid chromatography-mass spectrometry (LC-MS). The goal of this study was to highlight the broad application of this unified method. Thus, a stable isotope dilution analysis quantification method of the most important key food odorants in various food categories by LC-MS was developed. Using the well-known derivatization agent 3-nitrophenylhydrazine for carbonyl derivatization and a newly developed approach for alcohol and thiol derivatization, a method for the quantitation of 20 key food odorants was established. Intraday precision was determined to be ≤26%, and interday precision was between 24 and 31%. Limits of quantitation were determined between 0.014 and 283 μg/kg. The work shows that a wide array of aroma compounds can be analyzed accurately by LC-MS.

Integrated serum pharmacochemistry, network pharmacology and pharmacokinetics to explore bioactive components of Gushudan in the treatment of osteoporosis

Gushudan (GSD), a compound prescription on the basis of traditional Chinese medicine (TCM) theory and clinical practice, has been used in the treatment of osteoporosis (OP) for many years. Although studies have shown that GSD can treat OP, there is a lack of systematic screening method to explore the bioactive components, which are still unclear. Therefore, this study was aimed to establish an integrated method to screen and determine bioactive ingredients of GSD in the treatment of OP by serum pharmacochemistry, network pharmacology and pharmacokinetics. Firstly, 112 components of the GSD extract and 90 serum migrating constituents were identified by the ultra-high performance liquid chromatography-hybrid quadrupole-Orbitrap high-resolution mass spectrometry (UHPLC-Q-Orbitrap HRMS), most of which were derived from flavonoids, tanshinones, coumarins and organic acids. Secondly, based on the network pharmacological analysis of the serum migrating constituents, 37 core targets and 20 main pathways related to both GSD and OP were obtained. More importantly, 7 bioactive ingredients were further screened as the PK markers by the network topology parameters including icariin, icariside II, isopimpinellin, bergapten, imperatorin, osthole and tanshinone IIA. Finally, a sensitive and accurate quantitative method based on ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was established and validated for simultaneous determination of the 7 bioactive ingredients in the rat plasma after oral administration of GSD extract, which was then applied to pharmacokinetic study. Besides, the overall pharmacokinetic characteristics were further calculated: Cmax was 180.52 ± 31.18 ng/mL, Tmax was 0.46 ± 0.20 h, t1/2 was 4.09 ± 0.39 h, AUC0-∞ was 567.24 ± 65.29 ng·h/mL, which displayed quick absorption and medium elimination in rats after oral administration of GSD extract. This study provided a new and holistic insight for exploring bioactive constituents and main targets to decode the therapeutic material basis of GSD against OP.

Simultaneous determination of the nematicide fluensulfone and its two major metabolites in soils by ultra-high performance liquid chromatography-tandem mass spectrometry

A fast and sensitive method for simultaneously detecting nonfumigant nematicide fluensulfone (FSF) and its two major metabolites [3,4,4-trifluorobut-3-ene-1-sulfonic acid (BSA) and 5‑chloro-1,3-thiazole-2-sulfonic acid (TSA)] in different types of agricultural soils (black soil, krasnozem, sierozem) was established and validated through ultra-high performance liquid chromatography-tandem mass spectrometry. The samples were prepared by a modified quick, easy, cheap, effective, rugged, and safe method. The soil samples were firstly extracted with acetonitrile/water (4/1) and then purified with multi-walled carbon nanotubes (MWCNTs). Parameters influencing purification efficiency and recoveries, such as the type and the amount of sorbent were evaluated and compared. The overall average recoveries of three target analytes in soils were in the range of 73.1%-113.9% and the relative standard deviations (including intra-day and inter-day precision) were less than 12.7%. The limit of quantification was 5 μg/kg for all three compounds. The established method was successfully applied to examine the degradation of FSF and the formation of its two major metabolites in three different types of soil, indicating its efficacy in investigating the environmental behavior of FSF in agricultural soil system

Development of a liquid chromatography-tandem mass spectrometry (LC–MS/MS) method for characterizing pomegranate extract pharmacokinetics in humans

Pomegranate extracts standardized to punicalagins are a rich source of ellagitannins including ellagic acid (EA). Recent evidence suggests that gut microbiota-derived urolithin (Uro) metabolites of ellagitannins are pharmacologically active. Studies have evaluated the pharmacokinetics of EA, however, little is known about the disposition of urolithin metabolites (urolithin A (UA) and B (UB)). To address this gap, we developed and applied a novel ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) assay for the characterization of EA and Uro oral pharmacokinetics in humans. Subjects (10/cohort) received a single oral dose (250 or 1000 mg) of pomegranate extract (Pomella® extract) standardized to contain not less than 30 % punicalagins, < 5 % EA, and not less than 50 % polyphenols. Plasma samples, collected over 48 h, were treated with β-glucuronidase and sulfatase to permit comparison between unconjugated and conjugated forms of EA, UA and UB. EA and urolithins were separated by gradient elution (acetonitrile/water, 0.1 % formic acid) using a C18 column connected to a triple quadrupole mass spectrometer operating in the negative mode. Conjugated EA exposure was ∼5–8-fold higher than unconjugated EA for both dose groups. Conjugated UA was readily detectable beginning ∼8 h post-dosing, however, unconjugated UA was detectable in only a few subjects. Neither form of UB was detected. Together these data indicate EA is rapidly absorbed and conjugated following oral administration of Pomella® extract. Moreover, UA’s delayed appearance in the blood, primarily in the conjugated form, is consistent with gut microbiota-mediated metabolism of EA to UA, which is then rapidly converted to its conjugated form.

Widely untargeted metabolomic profiling unearths metabolites and pathways involved in leaf senescence and N remobilization in spring-cultivated wheat under different N regimes.

Progression of leaf senescence consists of both degenerative and nutrient recycling processes in crops including wheat. However, the levels of metabolites in flag leaves in spring-cultivated wheat, as well as biosynthetic pathways involved under different nitrogen fertilization regimes, are largely unknown. Therefore, the present study employed a widely untargeted metabolomic profiling strategy to identify metabolites and biosynthetic pathways that could be used in a wheat improvement program aimed at manipulating the rate and onset of senescence by handling spring wheat (Dingxi 38) flag leaves sampled from no-, low-, and high-nitrogen (N) conditions (designated Groups 1, 2, and 3, respectively) across three sampling times: anthesis, grain filling, and end grain filling stages. Through ultrahigh-performance liquid chromatography-tandem mass spectrometry, a total of 826 metabolites comprising 107 flavonoids, 51 phenol lipids, 37 fatty acyls, 37 organooxygen compounds, 31 steroids and steroid derivatives, 18 phenols, and several unknown compounds were detected. Upon the application of the stringent screening criteria for differentially accumulated metabolites (DAMs), 28 and 23 metabolites were differentially accumulated in Group 1_vs_Group 2 and Group 1_vs_Group 3, respectively. From these, 1-O-Caffeoylglucose, Rhoifolin, Eurycomalactone;Ingenol, 4-Methoxyphenyl beta-D-glucopyranoside, and Baldrinal were detected as core conserved DAMs among the three groups with all accumulated higher in Group 1 than in the other two groups. Kyoto Encyclopedia of Genes and Genomes pathway analysis revealed that tropane, piperidine, and pyridine alkaloid biosynthesis; acarbose and validamycin biosynthesis; lysine degradation; and biosynthesis of alkaloids derived from ornithine, lysine, and nicotinic acid pathways were the most significantly (p < 0.05) enriched in Group 1_vs_Group 2, while flavone and flavonol as well as anthocyanins biosynthetic pathways were the most significantly (p < 0.05) enriched in Group 1_vs_Group 3. The results from this study provide a foundation for the manipulation of the onset and rate of leaf senescence and N remobilization in wheat.

An Interesting Relationship between the Insecticidal Potential of Simarouba sp. in the Biology of Diamondback Moth

Alternative methods of insect management are an important field of study for agriculture. The current study aimed to determine the effect of aqueous extracts from Simarouba sp. (AE-S) on the biology of Plutella xylostella and to determine the toxicity of the extract to the nematode Caenorhabditis elegans (an important in vivo alternative assay system for toxicological study). Lyophilized AE-S was chemically investigated by Ultrahigh-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS). We evaluated the effect of the botanical extract on the life cycle of P. xylostella, from larval stage to adult stage, at concentrations of 10%, 5%, 1%, 0.1%, 0.05%, and 0.01% and a control. Subsequently, we analyzed the toxicity of the extract in an in vivo model. AE-S showed high amount of phenolic and flavonoid compounds. Six compounds were identified based on UHPLC-MS/MS analysis, including flavanone, kaempferol, 4,5-dimethoxycanthin-6-one, 11-acetylamarolide, ailanthinone, and glaucarubinone. The median lethal time for P. xylostella was estimated to be 96 h in all concentrations of AE-S, and at 120 h, 100% of the individuals were dead. Larvae exposed to AE-S at concentrations of 0.01, 0.05, and 0.1% showed a reduction in leaf area consumption, underdevelopment, and reductions in movement and pupal biomass. The lowest concentrations of AE-S (0.1%, 0.05%, and 0.01%) did not cause mortality in nematodes. Thus, the aqueous extract of Simarouba sp. could be an effective control tool because it mainly acts in the larval stage, the stage at which the insect causes damage to brassicaceae.

Association of polycyclic aromatic hydrocarbon metabolite concentration in urine and occupational stress in underground coal miners in China: propensity score and bayesian kernel machine regression.

This study intends to examine the association of urinary monohydroxyl PAHs (OH-PAHs) concentration and occupational stress in coal miners. We sampled 671 underground coal miners from Datong, China, assessed their occupational stress using the Occupational Stress Inventory-Revised edition (OSI-R), and categorized them into the high stress miners and controls based on that. We determined urinary OH-PAHs concentration using ultrahigh performance liquid chromatography-tandem mass spectrometry, and analyzed its association with occupational stress using multiple linear regression, covariate balancing generalized propensity score (CBGPS), and Bayesian kernel machine regression (BKMR). The low molecular weight (LMW) OH-PAHs in quartile or homologue was significantly positively associated with Occupational Role Questionnaire (ORQ) and Personal Strain Questionnaire (PSQ) score, but was not associated with Personal Resources Questionnaire (PRQ) score. The OH-PAHs concentration was positively associated with ORQ and PSQ scores in coal miners, particularly the LMW OH-PAHs. Non-association was found in the OH-PAHs with PRQ score.

Development and validation of method for analysis of favipiravir and remdesivir in volumetric absorptive microsampling with ultra high-performance liquid chromatography-tandem mass spectrophotometry.

Favipiravir and remdesivir are drugs to treat COVID-19. This study aims to find an optimum and validated method for simultaneous analysis of favipiravir and remdesivir in Volumetric Absorptive Microsampling (VAMS) by Ultra High-Performance Liquid Chromatography-Tandem Mass Spectrophotometry. The use of VAMS can be an advantage because the volume of blood is small and the sample preparation process is simple. Sample preparation was done by precipitation of protein using 500 μL of methanol. Analysis was carried out by ultra high-performance liquid chromatography-tandem mass spectrophotometry with ESI+ and MRM with m/z 157.9 > 112.92 for favipiravir, 603.09 > 200.005 for remdesivir, and at m/z 225.968 > 151.991 for acyclovir as the internal standard. The separation was carried out using an Acquity UPLC BEH C18 column (100 × 2.1 mm; 1.7 m), 0.2% formic acid-acetonitrile (50:50), flow rate was 0.15 mL/min, and column temperature was 50°C. The analytical method has been validated with the requirements issued by the Food and Drug Administration (2018) and European Medicine Agency (2011). The calibration range of favipiravir is 0.5-160 μg/mL and 0.002-8 μg/mL for remdesivir.

Development of UPLC-MS/MS method for the determination of colistin in plasma and kidney and its application in pharmacokinetics

Recently, the frequent emergence of multidrug-resistant gram-negative bacterial infections has forced colistin to be used as one of the last-line options for the treatment of these infections. This study aimed to establish and validate a simple, rapid, and reliable method for the quantitative determination of colistin in plasma and kidney homogenates by ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The pharmacokinetic parameters of colistin sulfate in rats and the relationship between renal accumulation and time of administration in rats were estimated by measuring plasma and renal colistin concentrations. The colistin in the sample was precipitated by acetonitrile, followed by extraction with nitrogen blow-drying and reconstitution. The chromatographic separation of analytes was conducted on an C18 column using a mobile phase consisting of 0.1% aqueous formic acid and acetonitrile. Polymyxin B was used as an internal standard (IS). Colistin and IS were monitored in positive ion mode with the following mass transition pairs: m/z 585.6→m/z 101.4 for colistin A，m/z 578.6→m/z 101.4 for colistin B and m/z 595.6→m/z 227.2 for IS, respectively. The established method expressed good linearity in 50 – 20000 ng·mL−1 of colistin, with the lower limit of quantification (LLOQ) of 50 ng·mL−1. Methodology validations, including accuracy, precision, matrix effect, recovery, stability, and dilution integrity met the US Food and Drug Administration (FDA) acceptance criteria for bioanalytical method validation. Noncompartmental pharmacokinetic parameters were obtained by the statistical moment theory. The estimates for the terminal half-life (t1/2), the peak time (Tmax), the peak concentration (Cmax), the area under the plasma concentration-time curve (AUC0−t), the volume of distribution (V), the total body clearance (CL) and the mean residence time (MRT0−t) were calculated to be 2.53 ± 1.6 h, 2.17 ± 1.57 h, 2913.01 ± 644.89 ng·mL−1, 15153.46 ± 3599.81 h·ng·mL−1, 0.98 ± 0.56 L·kg−1, 0.28 ± 0.09 L·h−1·kg−1 and 4.07 ± 1.13 h, respectively. And the concentrations of colistin in rat kidney tissue after continuous administration for 1, 3, 5, 7 days were 1.49 ± 0.35 μg·g−1, 2.88 ± 0.74 μg·g−1, 3.40 ± 0.25 μg·g−1 and 4.33 ± 0.63 μg·g−1, respectively. The established method provided a convenient, rapid, stable, sensitive, accurate way for the determination of colistin concentration, which has been successfully used for the pharmacokinetic analysis of colistin sulfate in rat and to explore the relationship between the renal accumulation of colistin and the duration of dosing.

Evaluation of Alternaria toxins in fruits, vegetables and their derivatives marketed in China using a QuEChERS method coupled with ultra-high performance liquid chromatography-tandem mass spectrometry: Analytical methods and occurrence

Alternaria species are invasive fungi that infect fruits and vegetables and produce Alternaria toxins resulting in loss of commodity values and harmful effects on human health. To establish a reliable analytical method for Alternaria toxins in fruits, vegetables and their derivatives (e.g., fruit and vegetable juices, purees and jams; dried fruit and vegetables; fruit and vegetable powders), a QuEChERS extraction method was developed and validated for the determination of most reported Alternaria toxins (alternariol monomethyl ether [AME], alternariol [AOH], tentoxin [TEN], tenuazonic acid [TeA], and altenuene [ALT]). The limits of quantitation (LOQ) of the target analytes in food matrices were 1.0–5.0 μg/kg. The extraction recoveries were 73.0%–120%, with good repeatability (<12.9%) and within-laboratory repeatability (<14.7%). The developed method was applied to 270 fruits, vegetables, and their derivatives randomly collected from the market in China. Approximately 45.2% of the samples were contaminated with varying levels of Alternaria toxins. The lowest incidence of contamination by Alternaria toxins was detected in fruits and vegetables (3.6%), and the highest incidence was found in fruit and vegetable powders (60.6%). TeA exhibited the highest detection frequency (22.6%) and the highest level of occurrence level (639 μg/kg) among the tested samples, followed by AOH (14.1%), ALT (11.9%), AME (4.4%), and TEN (3.3%). Furthermore, the simultaneous co-presence of two to five Alternaria toxins was detected in 13.7% of the analyzed samples. The combination of AOH + TeA was the most predominant, accounting for 4.8% of samples. This study developed a reliable and sensitive analytical method and provided representative occurrence data to support the assessment of emerging mycotoxins, especially Alternaria toxins, in fruit and vegetable products.

Immediate, sensitive and specific time-resolved fluorescent immunoassay strips based on immune competition for the detection of procymidone in vegetables

As an organochlorine pesticide, procymidone has become an increasing serious problem in vegetables in recent years. In order to solve a series of problems such as low sensitivity of the immunological methods, a time-resolved fluorescent immunoassay strip (TRFIAS) was developed with low limit of detection (LOD). Based on the principle of antigen-antibody immune competition, TRFIAS could detect procymidone in vegetables. After the targets being added, the samples were incubated at 37 °C for 10 min. TRFIAS was observed under a UV lamp of 365 nm. The results were processed by ImageJ software to complete the qualitative and quantitative analysis of TRFIAS. Under the optimal working conditions, a linear range of TRFIAS was 5–250 ng/mL with a LOD of 0.33 ng/mL and a visual limit of detection (VDL) of 50 ng/mL. And the TRFIAS had good specificity, precision and accuracy. Comparing the results of TRFIAS with those of ultrahigh-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), the two assays were in good agreement. Therefore, TRFIAS has the advantages of high sensitivity, high specificity, simple operation and relatively short assay time. Meanwhile, it shows absolutely great advantages in both quantitative and qualitative analysis.

Profiling GABA(A) Receptor Subunit Expression in the Hippocampus of PMDD Rat Models Based on TCM Theories.

γ-Aminobutyric acid type A receptors (GABAARs) play an important role in cognitive and emotional regulation and are related to the hippocampus. However, little is known regarding patterns of hippocampal GABAAR subunit expression in rat models of premenstrual dysphoric disorder (PMDD). This study investigated the above changes by establishing two PMDD rat models based on Traditional Chinese Medicine (TCM) theories, namely, PMDD liver-qi invasion syndrome (PMDD-LIS) and PMDD liver-qi depression syndrome (PMDD-LDS). Behavioral tests were used to detect depression and irritability emotion. Western blot analysis was used to investigate protein levels of GABAAR α1, α2, α4, α5, β2, β3, and δ subunits, whereas ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) analysis was performed to determine gamma-aminobutyric acid (GABA) and glutamate (Glu) levels in the hippocampus across each group. Concurrently, behavioral data indicated that the PMDD-LDS and PMDD-LIS rat models had been successfully established. GABAAR α2, α5, β2, and δ subunit was significantly upregulated, whereas α4 was significantly downregulated (P < 0.05) in PMDD-LDS rat models relative to controls. On the other hand, GABAAR α1, α2, and β3 were significantly downregulated while α4 and β2 were significantly upregulated in PMDD-LIS rat models relative to the control group (P < 0.05). Moreover, GABA levels significantly decreased, while Glu and the ratio of glutamate to GABA increased in PMDD-LIS rat models (P < 0.05). Conversely, GABA and Glu levels significantly decreased, whereas the ratio of glutamate to GABA increased in PMDD-LIS rat models (P < 0.05). Conclusively, our results revealed differential expression of GABAAR α1, α2, α4, α5, β2, β3, and δ subunits between PMDD-LIS and PMDD-LDS rat models, suggesting that they may be biomarkers in the pathogenesis of PMDD.