Performance Liquid Chromatography-tandem Mass Spectrometry Research Articles

Determination of cinnamaldehyde, thymol and eugenol in essential oils by LC–MS/MS and antibacterial activity of them against bacteria

Plant essential oils contain many secondary metabolites, some of which can effectively inhibit the growth of pathogenic microorganisms, so it is a very promising antibacterial agent. In this study, a qualitative and quantitative method based on high performance liquid chromatography–tandem mass spectrometry (HPLC–MS/MS) was developed for the simultaneous determination of three bioactive substances, cinnamaldehyde (CNM), thymol (THY), and eugenol (EUG), in the essential oils of plants. Necessary tests for linearity, limit of quantification, recovery, carryover contamination and precision of the method were carried out. Then, the antibacterial activity of 3 bioactive compounds against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was evaluated by minimal inhibitory concentration and the synergistic antimicrobial effect. The results indicated that CNM, THY and EUG had good antibacterial activity. According to the results of fractional inhibitory concentration index (FICI), it is considered that CNM + THY and CNM + THY + EUG has obvious synergistic inhibitory effect on E. coli, and CNM + THY and CNM + EUG has obvious synergistic inhibitory effect on S. aureus. Finally, we analyzed the effect of the bioactive compounds on trace elements in bacteria and found significant changes in magnesium, calcium, copper and iron.

Investigation of doxycycline residues in bones after oral administration to broiler chickens.

Chicken bones, a by-product of the poultry industry, can directly or indirectly enter the food chain. Bone meal and bone products could be sources of many contaminants. Considering the wide range of uses made of bones in the culinary and food industries, this material needs to be safe and antibiotic residue-free. To determine if such is the case, the concentration of doxycycline in chicken bones was investigated, this antimicrobial being one of the most commonly used in poultry production. Ross 308 broilers were grouped into three experimental and one control group. Doxycycline was administered in drinking water at therapeutic and sub-therapeutic doses, as well as via spray treatment. The concentration of doxycycline in bones was determined post slaughter by ultra-high performance liquid chromatography-tandem mass spectrometry. Doxycycline was quantified at 135 μg/kg 22 days after the last day of antibiotic administration at therapeutic doses; 2,285 μg/kg after sub-therapeutic treatment for 27 days and 9.62 μg/kg 22 days after the end of spray application. High concentrations and long persistence of doxycycline in bones were found in this study. Doxycycline can contaminate all bone-derived products in the food and fertiliser industries.

Development of a design of experiments (DOE) assistant modified QuEChERS method coupled with HPLC-MS/MS simultaneous determination of twelve lipid-soluble pesticides and four metabolites in chicken liver and pork

A modified QuEChERS method combined with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed for the determination of twelve lipid-soluble pesticides and four metabolites in chicken liver and pork. The QuEChERS method was optimized using two models, Plackett-Burman design and Central Composite Face-centered design, which enhanced its science and accuracy, making the optimization process more efficient and precise. Under optimal conditions, all coefficients of determination were > 0.9916. Limits of detection and limits of quantitation were 0.4–3.0 μg/kg and 1.0–10.0 μg/kg, respectively. In chicken liver, the recoveries (except for haloxyfop, haloxyfop-methyl, haloxyfop-etotyl, clodinafop-propargyl, and clodinafop) were 75.7–109.3% with relative standard deviations (RSDs) of 0.6–9.8%. In pork, the recoveries (except for difluorenican) were 73.4–104.7% with RSDs of 1.1–9.9%. Abnormal recoveries observed in this study could be attributed to the presence of esterase in chicken liver and pork. In addition, the method has been successfully applied to the detection of real samples. This study not only provides valuable data support for establishing maximum residue limits of target pesticides in chicken livers and pork, but also contributes an efficient and reliable detection tool for the animal-derived food safety monitoring system.

Simultaneous quantification of five antiretrovirals in human tissues using ultra-high performance liquid chromatography-tandem mass spectrometry methods for therapeutic drug monitoring at the sites of action

Although antiretroviral therapy (ART) is highly effective for the treatment of HIV-1 infection to suppress virus in the blood, HIV persists in tissues. HIV persistence in the tissues is due to numerous factors, and one of those factors are antiretroviral (ARV) concentrations. ARV concentrations in tissues must be adequate to suppress HIV at the sites of action. While therapeutic drug monitoring in the plasma is well-known, drug monitoring in the tissues provides local assessments of adequate ARV exposure to prevent localized HIV resistance formation. Towards these efforts, we validated an ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS/MS) method in human tissues (cervical, rectal, and vaginal tissues) for the simultaneous quantification of five ARVs: bictegravir, cabotegravir, dolutegravir, doravirine, and raltegravir. For this assay, protein precipitation with acetonitrile with stable, isotopically-labeled internal standards followed by supernatant pre-concentration was performed. Analyte separation was accomplished using a multistep UPLC gradient mixture of 0.1 % formic acid in water (A) and acetonitrile (B) with a Waters Cortecs T3 (2.1x100 mm) column. The assay was extensively validated as per the United States Food and Drug Administration Bioanalytical Method Validation Guidance over a clinically observed range (0.05–50 ng/mL) with superb linearity (R2 > 0.99 across all ARVs). The assay run time was 8.5 min. This analytical method achieves appropriate performance of trueness (85.5–107.4 %), repeatability, and precision (CV < 15 %). Our method will be employed for the therapeutic monitoring of guideline-recommended ARVs in human tissues for monitoring therapeutic efficacy in HIV treatment and prevention research efforts.

Localized Pantothenic Acid (Vitamin B5) Reductions Present Throughout the Dementia with Lewy Bodies Brain.

Localized pantothenic acid deficiencies have been observed in several neurodegenerative diseases such as Alzheimer's disease (AD), Parkinson's disease dementia (PDD), and Huntington's disease (HD), indicating downstream energetic pathway perturbations. However, no studies have yet been performed to see whether such deficiencies occur across the dementia with Lewy bodies (DLB) brain, or what the pattern of such dysregulation may be. Firstly, this study aimed to quantify pantothenic acid levels across ten regions of the brain in order to determine the localization of any pantothenic acid dysregulation in DLB. Secondly, the localization of pantothenic acid alterations was compared to that previously in AD, PDD, and HD brains. Pantothenic acid levels were determined in 20 individuals with DLB and 19 controls by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) across ten brain regions. Case-control differences were determined by nonparametric Mann-Whitney U test, with the calculation of S-values, risk ratios, E-values, and effect sizes. The results were compared with those previously obtained in DLB, AD, and HD. Pantothenic acid levels were significantly decreased in six of the ten investigated brain regions: the pons, substantia nigra, motor cortex, middle temporal gyrus, primary visual cortex, and hippocampus. This level of pantothenic acid dysregulation is most similar to that of the AD brain, in which pantothenic acid is also decreased in the motor cortex, middle temporal gyrus, primary visual cortex, and hippocampus. DLB appears to differ from other neurodegenerative diseases in being the only of the four to not show pantothenic acid dysregulation in the cerebellum. Pantothenic acid deficiency appears to be a shared mechanism of several neurodegenerative diseases, although differences in the localization of this dysregulation may contribute to the differing clinical pathways observed in these conditions.

Impact of homocysteine on acute ischemic stroke severity: possible role of aminothiols redox status

BackgroundAcute ischemic stroke (AIS) is one of the most common cerebrovascular diseases which accompanied by a disruption of aminothiols homeostasis. To explore the relationship of aminothiols with neurologic impairment severity, we investigated four aminothiols, homocysteine (Hcy), cysteine (Cys), cysteinylglycine (CG) and glutathione (GSH) in plasma and its influence on ischemic stroke severity in AIS patients.MethodsA total of 150 clinical samples from AIS patients were selected for our study. The concentrations of free reduced Hcy (Hcy), own oxidized Hcy (HHcy), free reduced Cys (Cys), own oxidized Cys (cysteine, Cyss), free reduced CG (CG) and free reduced GSH (GSH) were measured by our previously developed hollow fiber centrifugal ultrafiltration (HFCF-UF) method coupled with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The concentration ratio of Hcy to HHcy (Hcy/HHcy), Cys to Cyss (Cys/Cyss) were also calculated. The neurologic impairment severity of AIS was evaluated using National Institutes of Health Stroke Scale (NIHSS). The Spearman correlation coefficient and logistic regression analysis was used to estimate and perform the correlation between Hcy, HHcy, Cys, Cyss, CG, GSH, Hcy/HHcy, Cys/Cyss and total Hcy with NIHSS score.ResultsThe reduced Hcy and Hcy/HHcy was both negatively correlated with NIHSS score in AIS patients with P = 0.008, r=-0.215 and P = 0.002, r=-0.249, respectively. There was no significant correlation of Cys, CG, GSH, HHcy, Cyss, Cys/Cyss and total Hcy with NIHSS score in AIS patients with P value > 0.05.ConclusionsThe reduced Hcy and Hcy/HHcy, not total Hcy concentration should be used to evaluate neurologic impairment severity of AIS patient.

Amino acid metabolomics and machine learning for assessment of post-hepatectomy liver regeneration

ObjectiveAmino acid (AA) metabolism plays a vital role in liver regeneration. However, its measuring utility for post-hepatectomy liver regeneration under different conditions remains unclear. We aimed to combine machine learning (ML) models with AA metabolomics to assess liver regeneration in health and non-alcoholic steatohepatitis (NASH).MethodsThe liver index (liver weight/body weight) was calculated following 70% hepatectomy in healthy and NASH mice. The serum levels of 39 amino acids were measured using ultra-high performance liquid chromatography–tandem mass spectrometry analysis. We used orthogonal partial least squares discriminant analysis to determine differential AAs and disturbed metabolic pathways during liver regeneration. The SHapley Additive exPlanations algorithm was performed to identify potential AA signatures, and five ML models including least absolute shrinkage and selection operator, random forest, K-nearest neighbor (KNN), support vector regression, and extreme gradient boosting were utilized to assess the liver index.ResultsEleven and twenty-two differential AAs were identified in the healthy and NASH groups, respectively. Among these metabolites, arginine and proline metabolism were commonly disturbed metabolic pathways related to liver regeneration in both groups. Five AA signatures were identified, including hydroxylysine, L-serine, 3-methylhistidine, L-tyrosine, and homocitrulline in healthy group, and L-arginine, 2-aminobutyric acid, sarcosine, beta-alanine, and L-cysteine in NASH group. The KNN model demonstrated the best evaluation performance with mean absolute error, root mean square error, and coefficient of determination values of 0.0037, 0.0047, 0.79 and 0.0028, 0.0034, 0.71 for the healthy and NASH groups, respectively.ConclusionThe KNN model based on five AA signatures performed best, which suggests that it may be a valuable tool for assessing post-hepatectomy liver regeneration in health and NASH.

Human dementia with Lewy bodies brain shows widespread urea elevations

IntroductionSeveral recent studies have uncovered the presence of widespread urea elevations in multiple neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease dementia (PDD), vascular dementia (VaD), and Huntington's disease (HD). However, it is currently unknown whether dementia with Lewy bodies also shows these alterations in urea. This study aimed to investigate if and where urea is perturbed in the DLB brain. MethodsTissues from ten brain regions were obtained from 20 diagnosed cases of DLB and 19 controls. Urea concentrations were measured using ultra-high performance liquid chromatography–tandem mass spectrometry (UHPLC–MS/MS). Case–control differences were assessed by nonparametric Mann-Whitney U tests, and s-values, E-values, effect sizes, and risk ratios were determined for each brain region. The results were compared to those previously obtained for AD, PDD, VaD, and HD. ResultsAs with other previously investigated dementia diseases, DLB shows widespread urea elevations, affecting all ten regions investigated in the current study; the degree of these elevations is lower than that seen in AD or PDD, similar to that seen in HD, and higher than that observed in VaD. The highest urea fold-change was observed in the pons and the lowest in the primary visual cortex. ConclusionUrea elevations appear to be a shared alterations across at least five neurodegenerative diseases, despite their many differences in clinical and neuropathological presentation. The cause and effects of this perturbation should be the focus of future studies, for its possible contributions to the pathology of these conditions.

Determination of 13 potential anti-obesity agents in hair by dispersive liquid-liquid microextraction-assisted UHPLC-MS/MS

As the adulteration of dietary supplements with synthetic drugs remains a prevalent issue, the inclusion of anti-obesity agents may pose health risks, potentially leading to central nervous system or cardiovascular diseases. However, surveillance studies on the use of anti-obesity agents by the Chinese population are limited. This study aims to establish an efficient and rapid hair pretreatment method using dispersive liquid-liquid microextraction (DLLME) combined with high-speed grinding and develop a sensitive and accurate analytical method employing ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) for detecting 13 potential anti-obesity agents in hair samples. Herein, hair samples were washed sequentially with 0.1% sodium dodecyl sulfate (SDS), water and acetone, and then ground at high speed using 1 mL of an extraction solution (internal standard solution-n-butanol-1.2 mol/L Na2HPO4, pH10.0, 100:400:500, v/v/v for procaterol; internal standard solution-ethyl acetate-1.2 mol/L Na2HPO4, pH8.0, 100:300:600, v/v/v for other 12 anti-obesity agents) while simultaneously performing DLLME. The developed method successfully detected 13 anti-obesity agents within 11 min, including bambuterol, clenbuterol, ractopamine, clorprenaline, formoterol, salbutamol, terbutaline, procaterol, phentermine, bupropion, sibutramine, desmethyl sibutramine, and N,N-didesmethyl sibutramine, which improved the screening efficiency. The calibration curves exhibited good linearity of 0.025–5 ng/mg, achieving correlation coefficients of r ≥ 0.99. The lower limits of quantification (LLOQs) for the analytes were 0.025 ng/mg, demonstrating acceptable levels of accuracy and precision. Recovery rates ranged between 73.30% and 107.47% across the three concentrations of 0.075, 0.375, and 3.75 ng/mg. The validated method was successfully applied to 369 real cases and detected six analytes, including bambuterol, salbutamol, terbutaline, sibutramine, desmethyl sibutramine, and N,N-didesmethyl sibutramine. This method offers several advantages, including simple pretreatment, high extraction efficiency, rapid extraction, solvent economy, and pollution mitigation, making it highly suitable for large-scale surveillance of usage of added anti-obesity agents.

A developed and validated centrifugal ultrafiltration coupled with high performance liquid chromatography-tandem mass spectrometry method for rapid quantification of unbound lenvatinib in human plasma

In clinical practice, the determination of unbound drug concentration is very important for dose adjustment and toxicity prediction because only the unbound fraction can achieve a pharmacological effect. A fast, sensitive and accurate analytical method of centrifugal ultrafiltration coupled with high performance liquid chromatography-tandem mass spectrometry method was developed and applied to allow the quantification of unbound lenvatinib concentration. The application of linear regression analysis was used to examine the effects of centrifugal force, centrifugal time, and protein content on ultrafiltrate volume (Vu). The results indicated that the centrifugal force and centrifugal time have an influence on Vu that is significantly positive (P < 0.05). This developed method with good linearity (r2 = 0.9996), good accuracy (bias % ≤ 2.24 %), good precision (CV % ≤ 7.10 %), and good recovery (95.46 %−106.46 %) was suitable for routine clinical practice and studies. Particularly, the ultrafiltration membrane had no non-specific binding to lenvatinib. The unbound fractions can be separated in just 15 min. This method was applied to quantify clinical samples and to determine the plasma protein binding and unbound fraction of lenvatinib. This study provides a more effective and promising method for determination of unbound lenvatinib. It could be beneficial to measure the unbound concentration of lenvatinib in personalized medicine and therapeutic drug monitoring in routine clinical practice.

Sex and disease severity-based analysis of steroid hormones in ME/CFS

PurposeMyalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a debilitating disease characterized by persistent fatigue and decreased daily activity following physical and/or cognitive exertion. While ME/CFS affects both sexes, there is a higher prevalence in women. However, studies evaluating this sex-related bias are limited.MethodsCirculating steroid hormones, including mineralocorticoids (aldosterone), glucocorticoids (cortisol, corticosterone, 11-deoxycortisol, cortisone), androgens (androstenedione, testosterone), and progestins (progesterone, 17α-hydroxyprogesterone), were measured in plasma samples using ultra-high performance liquid chromatography–tandem mass spectrometry (UHPLC–MS/MS). Samples were obtained from mild/moderate (ME/CFSmm; females, n=20; males, n=8), severely affected patients (ME/CFSsa; females, n=24; males, n=6), and healthy controls (HC, females, n=12; males, n=17).ResultsAfter correction for multiple testing, we observed that circulating levels of 11-deoxycortisol, 17α-hydroxyprogesterone in females, and progesterone in males were significantly different between HC, ME/CFSmm, and ME/CFSsa. Comparing two independent groups, we found that female ME/CFSsa had higher levels of 11-deoxycortisol (vs. HC and ME/CFSmm) and 17α-hydroxyprogesterone (vs. HC). In addition, female ME/CFSmm showed a significant increase in progesterone levels compared to HC. In contrast, our study found that male ME/CFSmm had lower circulating levels of cortisol and corticosterone, while progesterone levels were elevated compared to HC. In addition to these univariate analyses, our correlational and multivariate approaches identified differential associations between our study groups. Also, using two-component partial least squares discriminant analysis (PLS-DA), we were able to discriminate ME/CFS from HC with an accuracy of 0.712 and 0.846 for females and males, respectively.ConclusionOur findings suggest the potential value of including steroid hormones in future studies aimed at improving stratification in ME/CFS. Additionally, our results provide new perspectives to explore the clinical relevance of these differences within specific patient subgroups.Graphical abstract

Investigation of the molecular mechanism of Smilax glabra Roxb. in treating hypertension based on proteomics and bioinformatics.

Smilax glabra Roxb. (named tufuling in Chinese, SGR) has both medicinal and edible value. SGR has obvious pharmacological activity, especially in anti-inflammation and treating immune system diseases. This study investigated differential protein expression and its relationship with immune infiltration in hypertension treated with SGR using proteomics and bioinformatics. N-Nitro L-arginine methyl ester (L-NAME) was used to replicate the hypertension model, with SGR administered by gavage for 4 weeks, and the systolic and diastolic blood pressure in each group of rats was measured using the tail-cuff method every 7 days. Furthermore, enzyme-linked immunosorbent assay (ELISA) was used to determine the serum total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) expressions in each group, followed by the detection of protein expression in rat liver samples using the tandem mass tag (TMT) technique. Additionally, hub targets were output using Cytoscape 3.9.1 software, and ALDH2 expression in the liver and serum in each group of rats was detected by ELISA. Moreover, R4.3.0 software was used to evaluate the relationship between acetaldehyde dehydrogenase 2 (ALDH2) and immune cells, and ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was performed to identify the components of SGR. Furthermore, the association between components of SGR and ALDH2 was analyzed with molecular docking and LigPlot1.4.5 software. Compared with the model group (L-NAME), SGR at high and medium doses reduced systolic and diastolic blood pressure while reducing TC, TG, and LDL-C levels and increasing HDL-C levels in hypertensive rats (p < 0.05). Moreover, 92 differentially expressed proteins (DEPs) were identified using TMT. These DEPs participated in peroxisome functioning, fatty acid degradation, and other signaling pathways, with ALDH2 being the core target and correlated with various immune cells. In addition, 18 components were determined in SGR, with 8 compounds binding to ALDH2. Molecular docking was performed to confirm that SGR played a role in hypertension based on the combined action of multiple components. In conclusion, SGR has an antihypertensive effect on L-NAME-induced hypertension, with ALDH2 as its hub target. SGR may regulate neutrophil, regulatory T cell, and other cells' infiltration by targeting ALDH2, thereby contributing to the treatment of hypertension.

Simultaneous Quantification of Vancomycin, Linezolid and Voriconazole in Human Plasma by UHPLC-MS/MS: Application in Therapeutic Drug Monitoring.

Individual differences challenge the treatment of vancomycin, linezolid and voriconazole in severe infections. This study aimed to build a simple and economical method for simultaneous determination of the three antibiotics in human plasma by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) and provided a reference for therapeutic drug monitoring (TDM) of infected patients. The plasma samples were precipitated by acetonitrile and detected and separated on a shim-pack GIST C18 column following the gradient elution within 5min. Mass quantification was performed on multiple reaction monitoring mode under positive electrospray ionization. The linear ranges of vancomycin, linezolid and voriconazole were 1.00-100.00, 0.10-15.00 and 0.10-20.00μg·mL-1, respectively, with good linearity (R2 > 0.99). The accuracy and precision, matrix effect, extraction recovery and stability were validated, and the results all meet the acceptance criteria of China Food and Drug Administration (CFDA) guidelines. The UHPLC-MS/MS method was established and validated for the simultaneous determination of vancomycin, linezolid and voriconazole in human plasma and successfully applied to routine TDM for individualized treatment.

Transcriptomics and UHPLC-QQQ-MS analyses reveal the dysregulation of branched chain amino acids metabolism in renal fibrotic rats

The dysregulated levels of branched chain amino acids (BCAA) contribute to renal fibrosis in chronic kidney disease (CKD), yet specific analysis of BCAA contents and how they are regulated still remain unclear. It is therefore of great scientific interest to understand BCAA catabolism in CKD and develop a sensitive method for simultaneous determination of individual BCAA and their metabolites branched chain α-ketoacids (BCKA). In this work, the important role of BCAA metabolism that drives renal fibrosis in the process of CKD was first revealed by using transcriptomics. The key target genes controlling BCAA metabolism were then validated, that is, mRNA levels of BCKDHA and BCKDHB, the regulating rate-limiting enzymes during BCAA metabolism were abnormally reduced by quantitative PCR (qPCR), and a similar drop-off trend of protein expression of BCKDH, HIBCH and MCCC2 that are closely related to BCAA metabolism was also confirmed by western blotting. Furthermore, we established a novel strategy that simultaneously determines 6 individual BCAA and BCKA in serum and tissue. The method based on dansylhydrazine derivatization and ultra-high performance liquid chromatography-tandem triple quadrupole mass spectrometry (UHPLC-QQQ-MS) achieved to simultaneously determine the contents of BCAA and BCKA, which is efficient and stable. Compared with normal rats, levels of BCAA including leucine, isoleucine and valine in serum and kidney of CKD rats was decreased, while BCKA including α-ketoisocaproic acid, α-ketomethylvaleric acid and α-ketoisovaleric acid was increased. Together, these findings revealed the abnormality of BCAA metabolism in driving the course of kidney fibrosis and CKD. Our current study sheds new light on changes in BCAA metabolism during CKD, and may facilitate development of drugs to treat CKD and renal fibrosis.

Enantiomer-specific analysis of amphetamine in urine, oral fluid and blood.

Illegal amphetamine is usually composed of a racemic mixture of the two enantiomers (S)- and (R)-amphetamine. However, when amphetamine is used in medical treatment, the more potent (S)-amphetamine enantiomer is used. Enantiomer-specific analysis of (S)- and (R)-amphetamine is therefore used to separate legal medical use from illegal recreational use. The aim of the present study was to describe our experience with enantiomer-specific analysis of amphetamine in urine and oral fluid, as well as blood, and examine whether the distribution of the two enantiomers seems to be the same in different matrices. We investigated 1,722 urine samples and 1,977 oral fluid samples from prison inmates, and 652 blood samples from suspected drugged drivers, where prescription of amphetamine was reported. Analyses were performed using ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS-MS). The enantiomer separation was achieved by using a chiral column, and results from the method validation are reported. Samples containing <60% (S)-amphetamine were interpreted as representing illegal use of amphetamine. The distribution of the two enantiomers was compared between different matrices. In urine and oral fluid, the mean amount of (S)-amphetamine was 45.2 and 43.7%, respectively, while in blood, the mean amount of (S)-amphetamine was 45.8%. There was no statistically significant difference in the amount of (S)-amphetamine between urine and oral fluid samples and between urine and blood samples, but the difference was significant in blood compared to oral fluid samples (P < 0.001). Comparison of urine and oral fluid between similar populations indicated that enantiomers of amphetamine can be interpreted in the same way, although marginally higher amounts of (R)-amphetamine may occur in oral fluid. Oral fluid, having several advantages, especially during collection, could be a preferred matrix in testing for illegal amphetamine intake in users of medical amphetamine.

Changes of PK/PD of Meropenem in patients with abdominal septic shock and exploration of clinical rational administration plan: a prospective exploratory study

This study aimed to explore the changes of pharmacokinetic parameters after meropenem in patients with abdominal septic shock after gastrointestinal perforation, and to simulate the probability of different dosing regimens achieving different pharmacodynamic goals. The study included 12 patients, and utilized high performance liquid chromatography-tandem mass spectrometry to monitor the plasma concentration of meropenem. The probability of target attainment (PTA) for different minimum inhibitory concentration (MIC) values and %fT > 4MIC was compared among simulated dosing regimens. The results showed that in 96 blood samples from 12 patients, the clearance (CL) of meropenem in the normal and abnormal creatinine clearance subgroups were 7.7 ± 1.8 and 4.4 ± 1.1 L/h, respectively, and the apparent volume of distribution (Vd) was 22.6 ± 5.1 and 17.2 ± 5.8 L, respectively. 2. Regardless of the subgroup, 0.5 g/q6h infusion over 6 h regimen achieved a PTA > 90% when MIC ≤ 0.5 mg/L. 1.0 g/q6h infusion regimen compared with other regimen, in most cases, the probability of making PTA > 90% is higher. For patients at low MIC, 0.5 g/q6h infusion over 6 h may be preferable. For patients at high MIC, a dose regimen of 1.0 g/q6 h infusion over 6 h may be preferable. Further research is needed to confirm this exploratory result.

Ultra-high performance liquid chromatography-tandem mass spectrometry assay for simultaneous determination of 22 marker compounds in traditional herbal medicine Ojeoksan

Traditional herbal medicines (THMs) have long been in use worldwide and are considered safe for use as tonics or complementary treatments for many diseases. Advanced quality control methods for THMs are required in the regulatory framework of modern medicines. In this study, an ultra-high performance liquid chromatography-tandem mass spectrometry assay was established for the simultaneous determination of 22 marker compounds in Ojeoksan (OJS), which is composed of 15 herbal substances. All marker compounds were analyzed within 20 min and successfully identified via scheduled multiple reaction monitoring. The method validation revealed excellent performance characteristics of the method such as specificity, linearity, sensitivity, precision, and accuracy, demonstrating its suitability for intended use. The developed method was applied to samples of commercial OJS tablet and soft-extract dosage forms. The 14 marker compounds corresponding to 12 component herbal substances were determined in the samples; ephedirine, albiflorin, paeoniflorin, ferulic acid, hesperidine, neohesperidin, cinnamic acid, platycodin D, 6-gingerol, atractylenolide III, glycyrrhizin, honokiol, decursin, and magnolol. A fast and easy assay method with sufficient discrimination power was established. As a novel assay, this method can contribute to the quality control of OJS products.

Determination of six bisphenols in human urine by ultra-high performance liquid chromatography-tandem mass spectrometry

To develop and validate a solid phase extraction-ultra-high performance liquid chromatography-tandem mass spectrometry method for the determination of six bisphenols(bisphenol S, bisphenol F, bisphenol A, 2, 2'-methylenediphenol, bisphenol AF, bisphenol AP) in urine. After enzymolysis of urine sample, the target substances were quickly purified and extracted by WAX solid phase extraction column. On ACQUITY BEH C_(18) column(2.1 mm×100 mm, 1.7 μm), the mobile phase of water and methanol was used to separate. Finally, multi-reaction detection was carried out under electrospray negative ion scanning, and quantification was carried out by internal standard method. The correlation coefficients(r) of the target compounds were all more than 0.998 in the range of 0.1-50.0 ng/mL, the linearity was good, and the detection limits were all lower than 0.1 ng/mL. The recoveries of the three standard concentrations(0.5, 5.0 and 50.0 ng/mL) were all between 80% and 120%, and the relative standard deviation was less than 20%(n=5). The standard reference material was detected and the concentration was within the reference range. This method can be used to detect six bisphenols in urine quickly and accurately, is suitable for the trace analysis of bisphenol compounds in human urine.

Elucidating hormone transduction and the protein response of soybean roots to drought stress based on ultra performance liquid chromatography–tandem mass spectrometry and four-dimensional data-independent acquisition

Drought stress can affect the growth and development of soybean, an important cultivated crop. As the main water-absorbing organ, it is particularly important to study the drought response mechanism of roots. Plant hormones are associated with almost all basic biological processes and are used as candidate targets for improving plant stress resistance by regulating cell signal transduction related to stress resistance. In this study, ultra performance liquid chromatography–tandem mass spectrometry (UPLC-MS/MS) and four-dimensional data-independent (4D-DIA) techniques were used to study the root hormone changes (5 %, 10 %, 15 % and 20 % drought stress level) and proteomic responses (15 % drought stress level) of different drought-tolerant varieties (drought-resistant HN44 and drought-sensitive HN65) under drought stress. The root activity, CAT activity and soluble sugar content of HN44 were basically higher than those of HN65 under different drought stress levels and days. In the two varieties, some plant hormones, such as abscisic acid (ABA) and salicylic acid (SA), accumulated with an increase in drought degree, and the accumulation of these hormones can give plants a certain degree of drought resistance. Most of the plant hormones peaked at 5–15 % drought stress level, and the overall content of jasmonic acid (JA) and cytokinin (CKs) decreased. Differences in the expression of key enzymes involved in hormone signal transduction, such as GH3, TCH4, and PR1, affect a variety of processes and lead to differences in drought resistance between the two varieties. In addition, HN44 had more upregulated proteins in important antioxidant pathways such as glutathione metabolism, phenylpropanoid biosynthesis, and isoflavone biosynthesis. Important drought-responsive proteins, such as PAL, 4CL, and VR, have also been characterized in HN44. In general, the drought-resistant variety was substantially better than the drought-sensitive variety in terms of hormone signaling and antioxidant capacity. These candidate proteins can be used as potential targets for improving drought resistance.

A novel enrichment and sensitive method for rapid determination of 4 sulfonamide antibiotics residues in fish

Sulfonamide antibiotics with superior performance are widely used in aquaculture. However, the residues of sulfonamide antibiotics in aquatic products may pose a threat to human health. In this work, a novel type of magnetic molecularly imprinted polymer (mMIP) was synthesized and coupled with ultra-high performance liquid chromatography–tandem mass spectrometry (UHPLC-MS/MS) for the selective separation and determination of 4 sulfonamide antibiotics residues in tilapia. The structure and adsorption properties of the polymers were characterized and evaluated. The key mMIP variables were investigated to determine the optimal magnetic solid phase extraction conditions. Results showed that the mMIPs had saturated adsorption capacities of 137.4, 78.7, 65.2, and 58.4 mg/g for trimethoprim, sulfadiazine, sulfamethazine, and sulfamethoxazole, respectively. Under optimized conditions, the linear range of the method for the detection of the 4 sulfonamides was 0.1–100 ng mL−1 (R > 0.991), the detection limit was 0.015 μg kg−1 (S/N = 3), the recovery rate was 78.6–101%, and the relative standard deviation (RSD%) was 4.2–7.8%. This new rapid and ultra-sensitive pretreatment method was successfully applied to the monitoring of trace sulfonamide antibiotics residues in fish samples.