A UHPLC–MS/MS method for the simultaneous determination of vancomycin,norvancomycin, meropenem,and moxalactam in human plasma and its clinical application

We developed an ultra-high-performance liquid chromatography–tandem mass spectrometry (UHPLC–MS/MS) method to determine four antibacterial drugs in human plasma for clinical usage. Samples were prepared using protein precipitation with methanol. Chromatographic separation was accomplished in 4.5 min on a BEH C18 column (2.1 × 50 mm, 1.7 μm) using a gradient elution of methanol and water (containing 7.71 g/L concentrated ammonium acetate, adjusted to pH 6.5 with acetic acid) at a flow rate of 0.4 mL/min. Positive electrospray was used for ionization. The method was linear in the concentration range 1–100 μg/mL for vancomycin, norvoncomycin, and meropenem; and 0.5–50 μg/mL for R-isomer of moxalactam and S-isomer of moxalactam. For all analytes, the intra- and inter-day accuracies and precisions were −8.47%–10.13% and less than 12%, respectively. The internal standard normalized recoveries and matrix effect were 62.72%–105.78% and 96.67%–114.20%, respectively. All analytes were stable at six storage conditions, with variations of less than 15.0%. The method was applied in three patients with central nervous system infection. The validated method might be useful for routine therapeutic drug monitoring and pharmacokinetic study.     

Development,validation, and implementation of an UHPLC–MS/MS method for the quantitation of furosemide in infant urine samples

Furosemide is a diuretic drug used to increase urine flow in order to reduce the amount of salt and water in the body. It is commonly utilized to treat preterm infants with chronic lung disease of prematurity. There is a need for a simple and reliable quantitation of furosemide in human urine. We have developed and validated an ultra-high performance liquid chromatography–tandem mass spectrometry method for furosemide quantitation in human urine with an assay range of 0.100–50.0 μg/ml. Sample preparation involved solid-phase extraction with 10 μl of urine. Intra-day accuracies and precisions for the quality control samples were 94.5–106 and 1.86–10.2%, respectively, while inter-day accuracies and precision were 99.2–102 and 3.38–7.41%, respectively. Recovery for furosemide had an average of 23.8%, with an average matrix effect of 101%. Furosemide was stable in human urine under the assay conditions. Stability for furosemide was shown at 1 week (room temperature, 4, −20 and −78°C), 6 months (−78°C), and through three freeze–thaw cycles. This robust assay demonstrates accurate and precise quantitation of furosemide in a small volume (10 μl) of human urine. It is currently being implemented in an ongoing pediatric clinical study.     

UHPLC method for the simultaneous determination of β-blockers, isoflavones, and flavonoids in human urine

A simple method using solid-phase extraction (SPE) and ultra high-performance liquid chromatography (UHPLC) for the simultaneous determination of β-blockers, isoflavones, and flavonoids in human urine is developed. A statistical central composite design and response surface analysis is used to optimize the separation of the analytes. These multivariate procedures are efficient in determining the optimal separation condition using resolutions and retention time as responses. A gradient elution using a mobile phase consisting of 0.05% trifluoroacetic acid in water and acetonitrile is applied on a Hypersil GOLD column within a short analysis time of 4.5 min. UV detection was used to monitor the analytes. The suggested method was linear in a concentration range from 0.04-20.00 μg/mL, depending on the compound. The limits of detection ranged from 8.9 to 66.2 ng/mL. The precision was lower than 2.74%, and the accuracy was between 0.01-3.65%. The Oasis HLB column, with the highest recoveries, is selected for the pre-concentration step. This present paper reports, for the first time, a method for the simultaneous determination of β-blockers, isoflavones, and flavonoids in human urine samples. Furthermore, the developed method can also be applied to the routine determination of examined compounds concentrations in human urine.     

On-line solid phase extraction fast liquid chromatography–tandem mass spectrometry for the analysis of bisphenol A and its chlorinated derivatives in water samples

In this study an on-line column-switching fast LC–MS/MS method was developed to analyze bisphenol A (BPA) and its chlorinated derivatives in water. Fast liquid chromatographic separation was performed on a C18 reversed phase column based on fused-core particle technology (2.7 μm particle size) providing analysis times shorter than 3 min and high peak efficiencies. The main benefit of this LC system is that it can easily be hyphenated to a conventional on-line preconcentration device allowing the direct analysis of water samples without any pretreatment at concentrations levels down to 60 ng L⁻¹ and preventing contaminations frequently reported in the analysis of BPA. This on-line SPE fast LC system was coupled to a triple quadrupole mass spectrometer operating in enhanced mass resolution mode (Q1 FWHM = 0.7 Th, Q3 FWHM = 0.1 Th) in order to minimize interferences and chemical noise. This highly sensitive and selective method was successfully employed to analyze BPA and its chlorinated derivatives in water samples.     

A new treatment by dispersive liquid–liquid microextraction for the determination of parabens in human serum samples

Alkyl esters of p-hydroxybenzoic acid (parabens) are a family of compounds that have been in use since the 1920s as preservatives in cosmetic formulations, with one of the lowest rates of skin problems reported in dermatological patients. However, in the last few years, many scientific publications have demonstrated that parabens are weak endocrine disruptors, meaning that they can interfere with the function of endogenous hormones, increasing the risk of breast cancer. In the present work, a new sample treatment method is introduced based on dispersive liquid–liquid microextraction for the extraction of the most commonly used parabens (methyl-, ethyl-, propyl-, and butylparaben) from human serum samples followed by separation and quantification using ultrahigh performance liquid chromatography–tandem mass spectrometry. The method involves an enzymatic treatment to quantify the total content of parabens. The extraction parameters (solvent and disperser solvent, extractant and dispersant volume, pH of the sample, salt addition, and extraction time) were accurately optimized using multivariate optimization strategies. Ethylparaben ring ¹³C₆-labeled was used as surrogate. Limits of quantification ranging from 0.2 to 0.7 ng mL^?1 and an interday variability (evaluated as relative standard deviations) from 3.8 to 11.9 % were obtained. The method was validated using matrix-matched calibration standard and a spike recovery assay. Recovery rates for spiked samples ranged from 96 to 106 %, and a good linearity up to concentrations of 100 ng mL^?1 was obtained. The method was satisfactorily applied for the determination of target compounds in human serum samples.     

A novel LC–MS/MS method for the determination of ziritaxestat in rat plasma and its pharmacokinetic study

Ziritaxestat is a first-in-class autotoxin inhibitor. The purpose of this study was to develop a liquid chromatography/electrospray ionization tandem mass spectrometric (LC–MS/MS) method for the determination of ziritaxestat in rat plasma. The plasma sample was deproteinated using acetonitrile and then separated on an Acquity BEH C₁₈ column with water containing 0.1% formic acid and acetonitrile as mobile phase, which was delivered at 0.4 ml/min. Ziritaxestat and the internal standard (crizotinib) were quantitatively monitored with precursor-to-product transitions of m/z 589.3 > 262.2 and m/z 450.1 > 260.2, respectively. The total running time was 2.5 min. The method showed excellent linearity over the concentration range 0.5–2000 ng/ml, with correlation coefficient >0.9987. The extraction recovery was >82.09% and the matrix effect was not significant. Inter- and intra-day precisions (RSD) were <11.20% and accuracies were in the range of −8.50–7.45%. Ziritaxestat was demonstrated to be stable in rat plasma under the tested conditions. The validated LC–MS/MS method was successfully applied to study the pharmacokinetic profiles of ziritaxestat in rat plasma after intravenous and oral administration. Pharmacokinetic results demonstrated that ziritaxestat displayed a short half-life (~3 h) and low bioavailability (20.52%).     

Establishment and validation of an SIL-IS LC–MS/MS method for the determination of ibuprofen in human plasma and its pharmacokinetic study

In this work, we developed and validated a highly sensitive, rapid and stable LC–MS/MS method for the determination of ibuprofen in human plasma with ibuprofen-d3 as a stable isotopically labeled internal standard (SIL-IS). Human plasma samples were prepared by one-step protein precipitation. The chromatographic separation was achieved on a Poroshell 120 EC-C₁₈ (2.1 × 50 mm, 2.7 μm). Aqueous solution (containing 0.05% acetic acid and 5 mm NH₄Ac) and methanol were selected as the mobile phase with gradient elution. An electrospray ionization source was applied and operated in negative ion mode. Multiple reaction monitoring mode was used for quantification using target fragment ions m/z 205.0 → 161.1 for ibuprofen and m/z 208.0 → 164.0 for SIL-IS, respectively. This method exhibited a linear range of 0.05–36 μg/ml for ibuprofen with correlation coefficient >0.99. Mean recoveries of ibuprofen in human plasma ranged from 78.4 to 80.9%. The RSD of intra- and inter-day precision were both < 5%. The accuracy was between 88.2 and 103.67%. The matrix effect was negligible in human plasma, including lipidemia and hemolytic plasma. A simple, efficient and accurate LC–MS/MS method was successfully established and applied to a pharmacokinetic study in healthy Chinese volunteers after a single oral administration of ibuprofen granules.     

A rapid and sensitive UPLC–MS/MS method for the determination of zanubrutinib in beagle plasma and its application in pharmacokinetics

A reliable and sensitive ultra-performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) method was developed for the determination of zanubrutinib in the plasma of beagle dogs. The column used was an Acquity BEH C₁₈ column (2.1 mm × 50 mm, 1.7 μm), maintained at 40°C with an injection volume of 2 μl. The gradient elution program was as follows: 0–1 min, 10–10% A; 1–1.1 min, 10–90% A; 1.1–2.1 min, 90–90% A; 2.1–2.2 min, 90–10% A; 2.2–3.0 min, 10–10% A. Mobile phase A was 0.1% formic acid, B was acetonitrile, and the total analysis time was 3 min. The mass spectrometry was performed in positive ion mode, and the scanning mode was multi-reaction monitoring mode with electrospray ionization as the ion source; m/z 472.2 → 455.01 for zanubrutinib and m/z 441.03 → 137.99 for ibrutinib (internal standard). The plasma samples were processed by protein precipitation. The standard curve showed good linearity (r² = 0.999 8) in the range of 1.0–1,000 ng/ml (zanubrutinib) with a low limit of quantification of 1 ng/ml. Also, the intra-day and inter-day precision (RSD) was <5.88% and the accuracy (RE) ranged from −1.56 to 1.08%; the recoveries of zanubrutinib in beagle plasma ranged from 90.12 to 93.53% (RSD 1.67–6.42%) and the ME values of zanubrutinib were 98.70–101.06% (RSD 5.37–8.49%, n = 6). All values meet US Food and Drug Administration requirements. A rapid, highly selective and sensitive method for the determination of zanubrutinib concentration in plasma by UPLC–MS/MS was successfully developed. This method is suitable for pharmacokinetic studies in beagle dogs by following oral administration of zanubrutinib.     

A simple and fast LC–MS/MS method for the simultaneous determination of tenofovir alafenamide and tenofovir in human plasma

A simple and fast liquid chromatography–tandem mass spectrometry method was established and validated for the simultaneous determination of tenofovir alafenamide (TAF) and tenofovir (TNF) in human plasma. A simple protein precipitation procedure was employed to extract analytes from plasma. Chromatographic separation was performed on an Eclipse Plus C₁₈ column utilizing a fast gradient elution starting with 2% of 2 mM ammonium acetate–formic acid (100/0.1, v/v) followed by increasing the percentage of acetonitrile. Detection was performed on a tandem mass spectrometer equipped with an electrospray ionization source operated in the positive ionization mode, using the transitions m/z 477.2 → m/z 346.1 for TAF and m/z 288.1 → m/z 176.1 for TNF. TAF-d₅ and TNF-d₇ were used as the internal standard of TAF and TNF, respectively. The method was validated in the concentration ranges 1.25–500 ng/mlfor TAF and 0.300–15.0 ng/ml for TNF with acceptable accuracy and precision.     

A MSALL quantitative method for the determination of Poloxamer 188 in rat plasma by UHPLC–Q-TOF/MS and its application to pharmacokinetic study

Poloxamer (PL)188 is a commonly used pharmaceutical excipient with unique physicochemical properties. In this study, an MS^ALL quantitative method for the determination of PL188 in rat plasma by UHPLC–Q-TOF/MS was developed and validated. PL188 was analyzed on PLRP-S reversed-phase column (50 × 4.6 mm, 8 μm, 1,000 Å) with mobile phase 0.1% formic acid–water and 0.1% formic acid in acetonitrile–isopropanol (2:3, v/v). The liner range was 0.1–10.0 μg/ml. A pharmacokinetic study was performed on rats at a dose of 5 mg/kg by intravenous injection. The pharmacokinetic parameters of intravenous injection were as follows: half-life was 2.0 ± 1.1 h, volume of distribution was 5.1 ± 3.2 L/kg, area under the concentration–time curve was 3.0 ± 0.6 μg/L h and clearance was 1.7 ± 0.3 L/h/kg. The results indicated that PL188 could be rapidly distributed to tissues with a high clearance rate. This study can provide a good reference for the further study of PL188.     

New UPLC–MS/MS method for simultaneous determination of irbesartan and hydrochlorthiazide in human plasma

Ultra-performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) is a preeminent analytical tool for rapid biomedical analysis with the objective of reducing analysis time and maintaining good efficiency. In this study a simple, rapid, sensitive and specific ultra-performance liquid chromatography–tandem mass spectrometry method was developed and validated for quantification of the angiotensin II receptor antagonist, irbesartan and hydrochlorthiazide in human plasma. After a simple protein precipitation using methanol and acetonitrile, irbesartan, hydrochlorthiazide and internal standard (IS) telmisartan were separated on Acquity UPLC BEH? C18 column (50 × 2.1 mm, i.d. 1.7 μm, Waters, USA) using a mobile phase consisting of acetonitrile:10 mM ammonium acetate:formic acid (85:15:0.1 % v/v/v) pumped at a flow rate of 0.3 mL/min and detected by tandem mass spectrometry with negative ion mode. The ion transitions recorded in multiple reaction monitoring mode were m/z 427.2 → 193.08 for irbesartan, m/z 295.93 → 268.90 for hydrochlorthiazide and m/z 513.2 → 287.14 for IS. The assay exhibited a linear dynamic range of 30–500 ng/mL for irbesartan and 1–500 ng/mL in human plasma with good correlation coefficient of (0.996) and (0.997) and with a limit of quantitation of 30  and 1 ng/mL for irbesartan and hydrochlorthiazide, respectively. The intra- and inter-assay precisions were satisfactory; the relative standard deviations did not exceed 10.13 % for irbesartan and 11.14 % for hydrochlorthiazide. The proposed UPLC–MS/MS method is simple, rapid and highly sensitive, and hence it could be reliable for pharmacokinetic and toxicokinetic study in both animals and humans.     

Validated HPLC–MS–MS method for determination of azithromycin in human plasma

A validated, highly sensitive, and selective HPLC method with MS–MS detection has been developed for quantitative determination of azithromycin (AZI) in human Na₂EDTA plasma. Roxithromycin (ROX) was used as internal standard. Human plasma containing AZI and internal standard was ultrafiltered through Centrifree Micropartition devices and the concentration of AZI was determined by isocratic HPLC–MS–MS. Multiple reaction monitoring mode (MRM) was used for MS–MS detection. The calibration plot was linear in the concentration range 2.55–551.43 ng mL⁻¹. Inter-day and Intra-day precision and accuracy of the proposed method were characterized by R.S.D and percentage deviation, respectively; both were less than 8%. Limit of quantification was 2.55 ng mL⁻¹. The proposed method was used to determine the pharmacokinetic profile of AZI (250-mg tablets).     

Assessment of synthetic cannabinoid FUB-AMB and its ester hydrolysis metabolite in human liver microsomes and human blood samples using UHPLC–MS/MS

FUB-AMB, an indazole carboxamide synthetic cannabinoid recreational drug, was one of the compounds most frequently reported to governmental agencies worldwide between 2016 and 2019. It has been implicated in intoxications and fatalities, posing a risk to public health. In the current study, FUB-AMB was incubated with human liver microsomes (HLM) to assess its metabolic fate and stability and to determine if its major ester hydrolysis metabolite (M1) was present in 12 authentic forensic human blood samples from driving under the influence of drug cases and postmortem investigations using UHPLC–MS/MS. FUB-AMB was rapidly metabolized in HLM, generating M1 that was stable through a 120-min incubation period, a finding that indicates a potential long detection window in human biological samples. M1 was identified in all blood samples, and no parent drug was detected. The authors propose that M1 is a reliable marker for inclusion in laboratory blood screens for FUB-AMB; this metabolite may be pharmacologically active like its precursor FUB-AMB. M1 frequently appears in samples in which the parent drug is undetectable and can point to the causative agent. The results suggest that it is imperative that synthetic cannabinoid laboratory assay panels include metabolites, especially known or potential pharmacologically active metabolites, particularly for compounds with short half-lives.     

Accurate and simple determination of oxcarbazepine in human plasma and urine samples using switchable-hydrophilicity solvent in GC–MS

This work presents a sensitive and rapid analytical method for the determination of oxcarbazepine in human plasma and urine samples. A vortex-assisted switchable hydrophilicity solvent-based liquid phase microextraction (VA–SHS–LPME) was used to preconcentrate oxcarbazepine from the samples before the determination by gas chromatography mass spectrometry. The switchable hydrophilicity solvent was synthesized by protonating N,N-dimethylbenzylamine with carbon dioxide to make it totally miscible with an equivalent volume of water. Parameters of the VA–SHS–LPME method including volume of switchable hydrophilicity solvent, concentration/volume of sodium hydroxide and vortex period were systematically optimized. Under the optimum conditions, good linearity ranging from 27.03 to 353.47 μg/kg was obtained for the analyte. Limit of detection and quantitation values were found to be 6.2 and 21 μg/kg (mass base), respectively. The relative standard deviation was calculated as 6.9% for six replicate measurements of the lowest concentration of the calibration plot. Satisfactory recovery results were calculated in the range of 97–100% for human plasma and urine samples spiked at five different concentrations.     

Protein precipitation method for determination of clobazam and N-desmethylclobazam in human plasma by LC–MS/MS

A protein precipitation method for the determination of clobazam (CLB) and its major active metabolite N-desmethylclobazam (N-CLB) in human plasma by liquid chromatography tandem mass spectrometry (LC–MS/MS) was established. CLB and N-CLB were extracted from human plasma samples by protein precipitation with methanol. Analyte separation was done using a Phenomenex Kinetex™ Biphenyl (50 × 2.1 mm, 1.7 μm) column using isocratic elution with a mobile phase of 5 mm ammonium formate with 0.01% ammonium hydroxide (40%) and methanol (60%) at a flow rate of 0.4 mL/min and an injection volume of 10 μL. The detection was performed on a triple quadrupole mass spectrometer in multiple reaction monitoring mode to monitor the precursor-to-product ion transitions of m/z 301.1 → 259.0, 306.0 → 263.9 for CLB and CLB-D5 and 287.0 → 245.0, 292.0 → 250.0 for N-CLB and N-CLB-D5 in positive electrospray ionization mode, respectively. The method was validated over a concentration range of 2.0–750 ng/mL for CLB and 0.7–200 ng/mL for N-CLB on SCIEX Triple Quad 4500 MS System. Total run time was 5 min. This method has been designed for bioequivalence study for formulations containing 20 mg of CLB.     

Development of a multianalyte method for the determination of anabolic hormones in bovine urine by isotope-dilution GC–MS/MS

A sensitive, specific and selective multianalyte GC–MS/MS method has been developed for the determination of 11 anabolic hormones in bovine urine. After adjusting the urine pH to 4.8, the samples were spiked with deuterated internal standards and submitted to enzymatic hydrolysis with β-glucuronidase/arylsulfatase. Hormones were eluted with methanol through a C18 solid phase cartridge and submitted to a liquid–liquid extraction. Analytes were derivatized by adding N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) with 1% trimethylchlorosilane and GC–MS data were obtained in the positive electron impact tandem mass mode. Under these conditions, no matrix effects were observed and limit of detection values were in the range of 0.005 ng/mL (diethylstilbestrol) to 0.38 ng/mL (17α-methyltestosterone and 17α-ethynylestradiol). Recoveries from 81% (α-zeranol) to 149% (17α-methyltestosterone) were found under the selected conditions. These results were better than those found using heptafluorobutyric anhydride (HFBA) as derivative reagent and those measured in full scan and selective ion monitoring modes.