scholarly journals Qualitative analysis of 7- and 8-hydroxyzolpidem and discovery of novel zolpidem metabolites in postmortem urine using liquid chromatography–tandem mass spectrometry

2022 ◽  
Author(s):  
Koji Yamaguchi ◽  
Hajime Miyaguchi ◽  
Youkichi Ohno ◽  
Yoshimasa Kanawaku
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Pyridine Ring ◽  
Multiple Reaction Monitoring ◽  
Fragmentation Pattern ◽  
The Novel ◽  
Flight Mass Spectrometry ◽  
Urine Extract ◽  
Liquid Chromatography Tandem Mass ◽  
Characteristic Fragmentation

Abstract Purpose Zolpidem (ZOL) is a hypnotic sometimes used in drug-facilitated crimes. Understanding ZOL metabolism is important for proving ZOL intake. In this study, we synthesized standards of hydroxyzolpidems with a hydroxy group attached to the pyridine ring and analyzed them to prove their presence in postmortem urine. We also searched for novel ZOL metabolites in the urine sample using liquid chromatography–triple quadrupole mass spectrometry (LC-QqQMS) and liquid chromatography–quadrupole time-of-flight mass spectrometry (LC-QqTOFMS). Methods 7- and 8-Hydroxyzolpidem (7OHZ and 8OHZ, respectively) were synthesized and analyzed using LC-QqQMS. Retention times were compared between the synthetic standards and extracts of postmortem urine. To search for novel ZOL metabolites, first, the urine extract was analyzed with data-dependent acquisition, and the peaks showing the characteristic fragmentation pattern of ZOL were selected. Second, product ion spectra of these peaks at various collision energies were acquired and fragments that could be used for multiple reaction monitoring (MRM) were chosen. Finally, MRM parameters were optimized using the urine extract. These peaks were also analyzed using LC-QqTOFMS. Results The presence of 7OHZ and 8OHZ in urine was confirmed. The highest peak among hydroxyzolpidems was assigned to 7OHZ. The novel metabolites found were zolpidem dihydrodiol and its glucuronides, cysteine adducts of ZOL and dihydro(hydroxy)zolpidem, and glucuronides of hydroxyzolpidems. Conclusions The presence of novel metabolites revealed new metabolic pathways, which involve formation of an epoxide on the pyridine ring as an intermediate.

scholarly journals A Hydrophilic Interaction Liquid Chromatography–Tandem Mass Spectrometry Quantitative Method for Determination of Baricitinib in Plasma, and Its Application in a Pharmacokinetic Study in Rats

Molecules ◽  
2020 ◽  
Vol 25 (7) ◽  
pp. 1600 ◽  
Author(s):  
Essam Ezzeldin ◽  
Muzaffar Iqbal ◽  
Yousif A. Asiri ◽  
Azza A Ali ◽  
Prawez Alam ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Tandem Mass Spectrometry ◽  
Multiple Reaction Monitoring ◽  
Internal Standard ◽  
Janus Kinase ◽  
Pharmacokinetic Studies ◽  
Tandem Mass ◽  
Chromatography Tandem Mass Spectrometry ◽  
Liquid Chromatography Tandem Mass

Baricitinib, is a selective and reversible Janus kinase inhibitor, is commonly used to treat adult patients with moderately to severely active rheumatoid arthritis (RA). A fast, reproducible and sensitive method of liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the quantification of baricitinib in rat plasma has been developed. Irbersartan was used as the internal standard (IS). Baracitinib and IS were extracted from plasma by liquid–liquid extraction using a mixture of n-hexane and dichloromethane (1:1) as extracting agent. Chromatographic separation was performed using Acquity UPLC HILIC BEH 1.7 µm 2.1 × 50 mm column with the mobile phase consisting of 0.1% formic acid in acetonitrile and 20 mM ammonium acetate (pH 3) (97:3). The electrospray ionization in the positive-mode was used for sample ionization in the multiple reaction monitoring mode. Baricitinib and the IS were quantified using precursor-to-production transitions of m/z 372.15 > 251.24 and 429.69 > 207.35 for baricitinib and IS, respectively. The method was validated according to the recent FDA and EMA guidelines for bioanalytical method validation. The lower limit of quantification was 0.2 ng/mL, whereas the intra-day and inter-day accuracies of quality control (QCs) samples were ranged between 85.31% to 89.97% and 87.50% to 88.33%, respectively. Linearity, recovery, precision, and stability parameters were found to be within the acceptable range. The method was applied successfully applied in pilot pharmacokinetic studies.

scholarly journals Ultraperformance Liquid Chromatography–Tandem Mass Spectrometry Assay for Iohexol in Human Serum

2009 ◽  
Vol 55 (6) ◽  
pp. 1196-1202 ◽  
Author(s):  
Thomas M Annesley ◽  
Larry T Clayton
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Human Serum ◽  
Matrix Effects ◽  
Multiple Reaction Monitoring ◽  
Internal Standard ◽  
Structural Analog ◽  
Limit Of Quantification ◽  
Iodinated Contrast ◽  
Liquid Chromatography Tandem Mass

Abstract Background: Iohexol is an iodinated contrast dye that has been shown to be useful in the estimation of glomerular filtration rate (GFR) in patients with suspected renal insufficiency. We developed and validated an ultraperformance liquid chromatography (UPLC)–triple quadrupole mass spectrometry (MS/MS) assay for quantifying iohexol in human serum. Methods: Sample preparation involved dilution of 50 μL serum with 400 μL water, followed by protein precipitation with zinc sulfate and methanol containing the structural analog ioversol as the internal standard. After 1:20 dilution of the supernatant with water, 5 μL was injected into the UPLC-MS/MS system. Chromatography was performed using a Waters Oasis HLB 5-μm particle size, 2.1 × 20 mm column maintained at 50 °C. We used a 1-step acetonitrile/0.1% formic acid gradient to elute the compounds of interest at a common retention time of 0.96 min. The multiple reaction monitoring transitions used for integration and quantification were m/z 821.7→803.7 for iohexol and m/z 807.9→589.0 for ioversol in the electrospray positive ionization mode. Results: The assay was linear from 2.5 mg/L (lower limit of quantification) to 1500 mg/L iohexol, with a mean extraction efficiency of >99%. Recovery of nominal target concentrations was 99%–102%. Interassay imprecision ranged from 7.9% at a concentration of 2.5 mg/L to 4.1% at 1000 mg/L. Ion suppression studies showed no matrix effects on the ionization of the 2 compounds. Conclusions: This rapid UPLC-MS/MS method can be successfully used for quantifying iohexol in human serum. .

Letter: High-Performance Liquid Chromatography/Electrospray Mass Spectrometry Analysis of the Mycotoxin Aurofusarin

2008 ◽  
Vol 14 (5) ◽  
pp. 329-333 ◽  
Author(s):  
Torsten Neuhof ◽  
Robert Köppen ◽  
Matthias Koch ◽  
Irene Nehls
Keyword(s):  
Mass Spectrometry ◽  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
High Performance ◽  
Multiple Reaction Monitoring ◽  
Food Samples ◽  
Mass Spectrometry Analysis ◽  
Tandem Mass ◽  
Fragmentation Pattern ◽  
Spectrometry Analysis

High-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) can be used for simultaneous quantification of various mycotoxins in contaminated food samples. Therefore, multi-mycotoxin methods have been developed in the last couple of years. To enlarge these methods for further analytes, we have developed a LC-MS/MS method for the quantification of the mycotoxin aurofusarin. Additionally, further LC-MS n experiments were performed to demonstrate the fragmentation pattern of aurofusarin. Applicable multiple reaction monitoring (MRM) transitions of aurofusarin were found and optimized by parameter variation of the tandem mass spectrometer. The applicability of the developed method was tested by analysis of naturally contaminated wheat.

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