Development and validation of an online SPE-HPLC-MS/MS for tire-derived pollutants of environmental concern (6PPD and 6PPD-Q): Detection and rainfall-driven dynamics in an urban river-estuary continuum.

Enantioselective high-performance liquid chromatography-tandem mass spectrometry method for bioanalysis and chemical and stereochemical stability study of N-ethylpentedrone.

The Harris County Institute of Forensic Sciences recently added brain to its fentanyl analog testing method for 14 analogs (fluoroisobutyryl fentanyl, acetyl fentanyl, acryl fentanyl, alfentanil, butyryl fentanyl, carfentanil, fentanyl, para-fluorofentanyl, furanyl fentanyl, methoxyacetyl fentanyl, norcarfentanil, norfentanyl, sufentanil, and valeryl fentanyl) and 3 U-series drugs (U-47700, U-48800, and U-49900). Brain is a protected and isolated organ with lower metabolic activity than other tissues, which can assist in interpreting results and preserving parent drug. Limited publications testing brain samples for fentanyl and fentanyl analogs exist and none describe homogenate stability for these analytes. Validation of the solid phase extraction and liquid chromatography tandem mass spectrometry method followed the ASB 036 Standard Practices for Method Validation in Forensic Toxicology and included limit of detection, limit of quantification, calibration model, bias and precision, ionization suppression/enhancement, interferences, carryover, processed sample stability, and dilution integrity. Carfentanil, fentanyl, furanyl fentanyl and methoxyacetyl fentanyl met quantitative bias and precision acceptance criteria in brain. To assess homogenate stability, brain homogenates (both unpreserved and preserved with 1% sodium fluoride) were fortified with 50 ng/mL of analyte, stored at room temperature (∼20°C), refrigerated (2-8°C), or frozen (∼-20°C), and analyzed in triplicate over a 90-day period. Analytes were considered stable if analyte/internal standard response ratio was within ± 20% of Day 0 and chromatographic peaks met qualitative acceptance criteria. Frozen brain homogenates could be stored for up to 90 days and withstood three freeze/thaw cycles for acetyl fentanyl, alfentanil, fentanyl, para-fluorofentanyl, FIBF, methoxyacetyl fentanyl, and norfentanyl. Brain homogenate stability was improved when frozen and was not impacted by the addition of 1% sodium fluoride. The study herein provides insight into the feasibility of testing brain for fentanyl analogs and their stability under various storage conditions, contributing valuable data to the limited literature on brain toxicology testing.

Detection and quantification of venlafaxine and its metabolite o-desmethylvenlafaxine in human hair using gas chromatography–tandem mass spectrometry method

Poly- and perfluoroalkyl substances (PFAS) are fluorinated organic chemicals, which include perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS). PFAS are persistent and bioaccumulate. PFAS can enter the food supply through plants and animals grown, raised, or processed in contaminated areas. This single-laboratory validation (SLV) study was conducted for a liquid chromatography tandem mass spectrometry (LC-MS/MS) method to determine 30 PFAS in a variety of foods, including produce, coffee, milk, protein powders, eggs, seafood, fish meat, edible offal, fish oil, baby food, and pet food, and compare with AOAC INTERNATIONAL Standard Method Performance Requirements (SMPR®) 2023.003. Matrixes were extracted using acetonitrile and QuEChERS reagents then purified by solid phase extraction (SPE) and concentrated under nitrogen. Fish meat did not require concentration under nitrogen, and fish oil and edible offal did not require QuEChERS reagents and sample concentration to reach the required limit of quantitation (LOQ). The LC-MS/MS system provides linear responses in the range of 0.01-25 µg/kg for most target analytes, depending on the matrix. Triplicate determinations over at least three spiking concentrations were made in each matrix with quantitation by isotopic dilution. We evaluated recovery, precision, retention time, blanks, ion ratios and S/N of the qualifier ions in all matrixes to determine the LOQ. Potential interference from cholic acids were separated chromatographically. The method developed and validated for the analysis of PFAS in food met the LOQ, and recovery and precision requirements of the SMPR. The LC-MS/MS method developed uses a single set of operating conditions enabling easy and rapid transfer of the method. The extraction is simplified, with only small variations necessary due to the sample matrix. The implementation of this method is cost effective to laboratories due to minimal solvent usage and labor required to extract samples.

Oxfendazole, a registered veterinary drug, has demonstrated broad-spectrum activity against multiple nematode species. First-in-human studies in healthy, predominantly Caucasian adults receiving a liquid formulation of oxfendazole demonstrated a favorable pharmacokinetic and safety profile, supporting its potential as a drug candidate for treating human helminth infections. To further advance its clinical development, we conducted a phase I bioavailability study using a field-applicable, immediate-release oxfendazole tablet. This trial investigated the pharmacokinetics, safety, and tolerability of the tablet formulation in healthy African adults residing in a filariasis-endemic country. Oxfendazole was administered as a single dose (100 or 400 mg) or as multiple doses (400 mg for 5 consecutive days) to 30 participants, randomized 8:2 to oxfendazole or placebo per cohort. Plasma concentrations of oxfendazole were measured using a validated high-performance liquid chromatography tandem mass spectrometry method, and pharmacokinetics were assessed using non-compartmental analysis. Peak plasma concentrations were reached after ~2.5-3 h. The median elimination half-life ranged from 11.6 to 13.9 h and was consistent across cohorts. Non-linear pharmacokinetics was observed, with exposure (AUC∞, Cmax) increasing less than dose-proportionally and showing high variability. Oxfendazole was well tolerated, with no adverse events reported and no clinically significant abnormalities in laboratory tests, vital signs, physical examinations, or electrocardiograms. These findings support the further development of oxfendazole in early proof-of-concept studies. Formulation optimization is suggested to reduce variability in exposure and improve the reliability of exposure-response assessments in future clinical trials.The study is registered with ClinicalTrials.gov as NCT04920292.

Per- and polyfluoroalkyl substances (PFAS) are an emerging group of environmental contaminants widely used in consumer products. Public unease regarding the levels of these compounds in the environment has called for methods to keep up with emerging PFAS and regulations. There is a need for analytical methods that are efficient and robust that can be readily used and easily accessed in commercial laboratories. This work discusses the development of an efficient, sensitive and reliable liquid chromatography tandem mass spectrometry method for the analysis of 40 PFAS in aqueous matrices (10min run time). Initial calibration demonstrated excellent linearity for all PFAS analytes with r 2 values greater than 0.997. Limit of detections (0.2-100ng/L) and limit of quantifications (1-350ng/L) show the ability for the method to reach necessary levels to stay up to date with federal and state regulations. Two solid phase extraction techniques were compared based on recovery accuracy and precision. Recoveries ranged from 92.0% to 105.0% and 67.0% to 109.0% for the automated and manual setups, respectively. Evidence was found to support improvements in sample recovery using an automated setup. The validated method was used to analyze samples from six natural water sources in the Baltimore-Metro area, where seven of the forty PFAS compounds were found in at least one sample.

A simple, selective, and sensitive liquid chromatography–tandem mass spectrometry method was developed and validated for the simultaneous quantification of p-Chloroamphetamine (PCA) in mouse plasma and brain tissue. Chromatographic separation was achieved using a Synergi Polar-RP column with gradient elution using 2 mM ammonium formate containing 0.2% formic acid and acetonitrile. Multiple reaction monitoring transitions were m/z 170.0→ 125.0 for PCA and m/z 214.2→ 154.0 for the internal standard, clorprenaline. The method was fully validated according to FDA and ICH guidelines, demonstrating excellent selectivity, linearity (1–1000 ng/mL), accuracy, precision, negligible matrix effects, consistent recovery, and adequate stability in both matrices. A simple methanol-based protein precipitation method enabled efficient extraction with minimal interference. The validated assay was applied to characterize the pharmacokinetics and brain distribution of PCA in male ICR mice following intravenous (1 mg/kg) and oral (10 mg/kg) administration. PCA showed extensive distribution after intravenous dosing, with a large steady-state volume of distribution (5788.42 ± 544.29 mL/kg), moderate clearance (26.92 ± 2.42 mL/min/kg), and a terminal half-life of 149.51 ± 13.98 min. After oral administration, PCA was absorbed with a mean Tmax of 160.0 ± 69.3 min, reaching a Cmax of 0.69 ± 0.39 µg/mL and an apparent oral bioavailability of 104.12%. Following oral dosing, PCA exhibited high total brain penetration, with brain-to-plasma ratios (Kp, brain) of 11.26–16.17 and unbound brain-to-plasma ratios (Kp, uu, brain) of 0.40–0.57. These findings provide the first comprehensive pharmacokinetic and brain distribution profile of PCA and offer quantitative insight into its central serotonergic and neurotoxic actions.

A robust and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the simultaneous quantification of 39 multi-class emerging contaminants (ECs), encompassing diverse groups including industrial chemicals (n = 6), pharmaceuticals (n = 19), personal care products (n = 4), and pesticides (n = 10). LC-MS/MS parameters were systematically optimized, including compound-specific transitions, source conditions, mobile phase composition, injection volumes, and chromatographic flow rates, to maximize signal intensity and ensure reproducible detection. Solid-phase extraction (SPE) was further optimized through evaluation of reconstitution solvent composition, evaporation settings, washing solvents, and elution strategies to improve recoveries and minimize matrix effects. The final method achieved instrument detection limits as low as 0.01 fg on-column, with method detection and quantitation limits of 0.01-1.32 ng/L and 0.03-3.96 ng/L, respectively. Calibration linearity (R² >0.99), recoveries within 70-130%, and intra-/inter-day precision (RSD ≤20%) confirmed the robustness and reproducibility of the protocol. Application to six real water matrices, bottled water, tap water, surface water, seawater, wastewater effluent, and influent, revealed the highest concentrations and widest range of analytes in influent, lower but quantifiable levels of persistent compounds in effluent, and predominantly trace-level detections or non-detects in natural and potable waters. Complementary greenness and applicability assessments using AGREE, MoGAPI, and BAGI highlighted moderate environmental sustainability and strong practical utility, reinforcing the suitability of the method for routine monitoring, source tracking, regulatory compliance, and risk assessment applications requiring ultra-trace sensitivity, high selectivity, and broad chemical coverage.

Metabolic stability assessment and metabolite profiling of gunagratinib, a novel FGFR inhibitor, in rat, monkey and human liver microsomes by an integrated analysis method based on HPLC-MS/MS and HPLC-Orbitrap-HRMS.

Identification and quantification of two etomidate analogues ABP-700 and 2,6-dichloro-3-fluoro-etomidate in e-cigarette liquid and hair by GC-MS and LC-MS/MS.

BackgroundDue to the high risk of invasive fungal disease (IFD) in acute myeloid leukemia (AML) patients, the antifungal drug posaconazole is often co-administered with venetoclax. As posaconazole is a potent inhibitor of CYP3A4, the standard dosing regimen may lead to the elevated plasma concentrations of venetoclax due to potential drug-drug interactions (DDIs). Therefore, therapeutic drug monitoring (TDM) is necessary to optimize the dosage.MethodsThis study developed and validated a rapid and sensitive ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method for the simultaneous quantification of venetoclax and posaconazole in human plasma. Plasma samples were pretreated using acetonitrile precipitation. The chromatographic separation was achieved using an Acquity BEH C18 column with gradient elution. The mobile phase consisted of 0.1% formic acid in water and acetonitrile, with a flow rate of 0.4 mL/min.ResultsThe method demonstrated good sensitivity and linearity within the concentration ranges of 10–15,000 ng/mL for venetoclax and 10–10,000 ng/mL for posaconazole, respectively. Additionally, the method showed acceptable selectivity, intra-day precision, inter-day precision, accuracy, matrix effects (95.2% to 102.0% for venetoclax and 98.4% to 102.5% for posaconazole), extraction recovery (93.2% to 95.4% for venetoclax and 87.8% to 95.8% for posaconazole), and stability under various conditions. The trough concentrations of venetoclax were 9326.88 ± 12,169.05 ng/mL in patients treated with venetoclax alone, and 31,623.55 ± 28,453.67 ng/mL in patients treated with venetoclax in combination with posaconazole.ConclusionA rapid and simple method was established and successfully applied to the simultaneous determination of the concentrations of venetoclax and posaconazole in AML patients, providing a basis for TDM and clinical pharmacokinetic analysis of these drugs in AML patients.

Abstract Background Central nervous system tuberculosis (CNS TB), including tuberculous meningitis, is a life-threatening condition with high mortality rates [1]. Contezolid, a next-generation oxazolidinone antibiotic, has shown comparable efficacy to linezolid but with a significantly improved safety profile [2]. This exploratory study evaluated the pharmacokinetics (PK), and blood-brain barrier penetration of contezolid tablets in seven adult patients with CNS TB.Figure 1Concentration-time curves of contezolid in plasma and CSF at steady-stateFigure 2Contezolid CSF plasma concentration ratio Methods Participants received a standardized anti-TB regimen, which includes rifampin: 10 mg/kg/day (maximum 600 mg), isoniazid: 5 mg/kg/day (maximum 600 mg), pyrazinamide: 30 mg/kg/day (maximum 2 g), levofloxacin: 500 mg/day, and dexamethasone and mannitol for adjunctive therapy. In addition to this regimen, contezolid tablets were administered at a dose of 800mg every 12 hours. Blood and cerebrospinal fluid (CSF) samples were collected prior to the first dose and at day 8 for PK assessments..Drug concentrations were measured by a validated liquid chromatography tandem mass spectrometry method. The steady-state PK parameters of contezolid in plasma and CSF were calculated using a noncompartmental model method. The blood-brain barrier penetration of contezolid was evaluated by the ratio of CSF to plasma drug concentration and exposure. Results At steady-state, the plasma AUC0-12,ss and AUC0-∞,ss were 107.77±55.64 mg·h/L and 118.00±60.21 mg·h/L, whereas the CSF values were 11.40±3.14 mg·h/L and 16.62±12.24 mg·h/L, with penetration rates of 10.58% and 14.08%, respectively. The Tmax,ss in plasma and CSF were 3 h (1.5–6 h) and 6 h (3–9 h), and the CSF to plasma drug concentration ratio increased with time, indicating delayed drug entry into the CSF. The T1/2,ss in plasma and CSF were 2.49 h (1.17–4.54 h) and 3.18 h (1.39–10.42 h), suggesting slower elimination in CSF. The plasma clearance (CLss_F) and volume of distribution (Vss_F) were 9.00±3.86 L/h and 32.61±13.85 L, respectively. Conclusion Contezolid demonstrated moderate CSF penetration, but its CSF concentrations were markedly lower than plasma levels, indicating restricted distribution across the blood-brain barrier. Disclosures All Authors: No reported disclosures

Endometrial cancer is the most common gynecologic malignancy globally. Recent studies suggest that alterations in circadian rhythm might be associated with an increased risk of endometrial carcinoma. To evaluate the association between sleep quality, urinary melatonin levels, and prevalence of endometrial cancer. A case control study was conducted among perimenopausal women with recently diagnosed endometrial cancer. Women with no history of cancer were recruited as controls. Sleep evaluation was done using the Pittsburgh Sleep Quality Index (PSQI). Urinary melatonin levels were measured using liquid chromatography tandem mass spectrometry methods. The sociodemographic variables (age, education, occupation, and diet) as well as the variables of PSQI scores and melatonin levels were compared between cases and healthy controls. The mean ± SD age of cases was 50.7 ± 11.2 (n = 18), and it does not differ significantly from the controls, 48.2 ± 2.6 (n = 18). The PSQI global scores mean (SD) among cases, 8.77 ± 3.76, was significantly higher as compared to controls, 6.27 ± 2.71 (P = 0.03). The sleep onset latency was significantly higher among patients (P = 0.002), and sleep duration scores are significantly different between cases and controls (P = 0.006). The melatonin level mean ± SD among cases, 6.72 ± 2.71 ng/mL, was significantly low as compared to controls, 12.38 ± 6.64 ng/mL (P = 0.006). Low melatonin levels along with sleep quality in endometrial carcinoma patients indicate that the malignancy might be associated with disturbances in the circadian rhythm.

A new deep field scan liquid chromatography-mass spectrometry method to identify host cell proteins in therapeutic proteins.

Establishment of a LC-MS/MS method for the simultaneous quantitative determination of trimethylamine N-oxide and four precursors in human saliva.

LC-MS/MS quantitation of the primary reduced metabolites of progesterone in serum during the third trimester of human pregnancy reveals a potential role for 20β-hydroxyprogesterone and 5β-dihydroprogesterone in functional progesterone withdrawal.

Avacopan is a new treatment for antineutrophil cytoplasmic antibody-associated vasculitis (ANCA-AAV). To date, there has been a lack of published bioanalytical methods to assay it in plasma, resulting in sparse pharmacokinetic data in clinical settings. The objective of this study was to develop and validate a liquid chromatography tandem mass spectrometry (LC-MS/MS) method for the quantification of avacopan in human plasma. [2H4]-Avacopan was as used as internal standard (IS). Samples were prepared by protein precipitation and separated was on an Accurore® C18 column (2.1 ×50 mm, 2.6 µm), with an elution gradient at a flow rate of 0.5 mL/min. The mobile phase consisted of acetonitrile (0.1 % formic acid) and water (0.1 % formic acid). The analysis run time was 6 min. Avacopan was detected by electrospray ionization on a TSQ Quantis® triple quadrupole mass spectrometer (ThermoFisher Scientific). The linearity of method ranged from 10 to 800 ng/mL. The within-run and between-run relative standard deviations were < 10.2 %. The within-run and between-run relative errors ranged from 2.4 % to 14.4 %. The IS-normalized matrix effect ranged from 2.2 % to 5.1 %, and the IS-normalized extraction recovery ranged from 104.3 % to 109.7 %. The method was fully validated, including checks on linearity, dilution integrity and carry-over. Plasma samples from 16 patients undergoing treatment for ANCA-AAV were then successfully treated with the method. The reanalysis of the samples incurred was below 14 %. This method is suitable for plasma drug monitoring of avacopan because it is both accurate and precise, and meets all validation criteria.

An LC-MS/MS method for simultaneous quantification of pyrotinib, docetaxel and paclitaxel in human plasma and its application to therapeutic drug monitoring.

An LC-MS/MS method for the quantification of doxorubicin uptake in zebrafish larvae breast cancer xenografts.