+ Site Statistics
+ Search Articles
+ PDF Full Text Service
How our service works
Request PDF Full Text
+ Follow Us
Follow on Facebook
Follow on Twitter
Follow on LinkedIn
+ Subscribe to Site Feeds
Most Shared
PDF Full Text
+ Translate
+ Recently Requested

Gas chromatography/negative ion chemical ionization mass spectrometry and liquid chromatography/electrospray ionization tandem mass spectrometry quantitative profiling of N-acetylcysteine conjugates of valproic acid in urine: application in drug metabolism studies in humans



Gas chromatography/negative ion chemical ionization mass spectrometry and liquid chromatography/electrospray ionization tandem mass spectrometry quantitative profiling of N-acetylcysteine conjugates of valproic acid in urine: application in drug metabolism studies in humans



Journal of Mass Spectrometry 35(6): 698-704



We report a GC/NICI-MS assay and a LC/ESI-MS/MS assay for the analysis of N-acetylcysteine (NAC) conjugates of (E)-2,4-diene VPA (NAC I and NAC II) identified in humans. The assay also includes the analysis of the NAC conjugate of 4,5-epoxy VPA (NAC III), an identified metabolite in rats treated with 4-ene VPA for its use in metabolic studies in animals. The highly sensitive GC/MS assay was designed to monitor selectively the diagnostic and most abundant [M - 181](-) fragment anion of the di-PFB derivatives of NAC I, NAC II, and NAC IV, the internal standard (IS) and the PFB derivative of NAC III. The higher selectivity of LC/MS/MS methodology was the basis for an assay which could identify and quantitate the underivatized conjugates simultaneously using MRM of the diagnostic ions m/z 130 and 123 arising from the CID of their protonated molecular ions [MH](+). The GC/MS assay employed liquid-liquid extraction whereas the LC/MS/MS assay used a solid-phase extraction procedure. Linearity ranges of the calibration curves were 0.10-5.0microg ml(-1) by GC/MS and 0.10-1.0microg ml(-1) by LC/MS/MS for NAC I, NAC II and NAC III (r(2) = 0.999 or better). Both assays were validated for NAC I and NAC II and provided good inter- and intra-assay precision and accuracy for NAC I and NAC II. The LOQ by LC/MS/MS was 0.1microg ml(-1), representing 1 ng of NAC I and NAC II. The same LOQ (0.1microg ml(-1)) was observed by GC/MS and was equivalent to 100 pg of each metabolite. NAC III was detected at concentrations as low as 0.01 microg ml(-1) by both methods. The total urinary excretion of the NAC conjugates in four patients on VPA therapy was determined to be 0.004-0.088% of a VPA dose by GC/MS and 0.004-0. 109% of a VPA dose by LC/MS/MS.

Please choose payment method:






(PDF emailed within 0-6 h: $19.90)

Accession: 010696217

Download citation: RISBibTeXText

PMID: 10862121

DOI: 10.1002/1096-9888(200006)35:6<698::aid-jms996>3.0.co;2-s


Related references

Artifact-free quantification of free 3-chlorotyrosine, 3-bromotyrosine, and 3-nitrotyrosine in human plasma by electron capture-negative chemical ionization gas chromatography mass spectrometry and liquid chromatography-electrospray ionization tandem mass spectrometry. Analytical Biochemistry 300(2): 252-259, 2002

Electrospray and chemical ionization mass spectrometry of di-n-butyl sulfate. Unimolecular chemistry of its protonated form and quantification method by liquid chromatography/electrospray ionization tandem mass spectrometry. Rapid Communications in Mass Spectrometry 14(15): 1410-1416, 2000

Electrospray ionization mass spectrometry of 5-methyl-2'-deoxycytidine and its determination in urine by liquid chromatography/electrospray ionization tandem mass spectrometry. Rapid Communications in Mass Spectrometry 13(21): 2160-2165, 1999

High-resolution liquid chromatography/electrospray ionization time-of-flight mass spectrometry combined with liquid chromatography/electrospray ionization tandem mass spectrometry to identify polyphenols from grape antioxidant dietary fiber. Rapid Communications in Mass Spectrometry 22(22): 3489-3500, 2008

Improved characterization of tomato polyphenols using liquid chromatography/electrospray ionization linear ion trap quadrupole Orbitrap mass spectrometry and liquid chromatography/electrospray ionization tandem mass spectrometry. Rapid Communications in Mass Spectrometry 24(20): 2986-2992, 2010

Quantitative determination of rhein in human plasma by liquid chromatography-negative electrospray ionization tandem mass/mass spectrometry and the application in a pharmacokinetic study. Journal of Pharmaceutical and Biomedical Analysis 57: 19-25, 2012

Diclofenac in municipal wastewater treatment plant: quantification using laser diode thermal desorption--atmospheric pressure chemical ionization--tandem mass spectrometry approach in comparison with an established liquid chromatography-electrospray ionization-tandem mass spectrometry method. Journal of Chromatography. a 1433: 106-113, 2016

Ionization enhancement in atmospheric pressure chemical ionization and suppression in electrospray ionization between target drugs and stable-isotope-labeled internal standards in quantitative liquid chromatography/tandem mass spectrometry. Rapid Communications in Mass Spectrometry 17(24): 2815-2821, 2003

Capillary zone electrophoresis-electrospray ionization-tandem mass spectrometry as an alternative proteomics platform to ultraperformance liquid chromatography-electrospray ionization-tandem mass spectrometry for samples of intermediate complexity. Analytical Chemistry 84(3): 1617-1622, 2012

Analysis of phytochelatin-cadmium complexes from plant tissue culture using nano-electrospray ionization tandem mass spectrometry and capillary liquid chromatography/electrospray ionization tandem mass spectrometry. Journal of Mass Spectrometry 34(9): 930-941, 1999

Quantification of urinary excretion of 1,N6-ethenoadenine, a potential biomarker of lipid peroxidation, in humans by stable isotope dilution liquid chromatography-electrospray ionization-tandem mass spectrometry: comparison with gas chromatography-mass spectrometry. Chemical Research in Toxicology 17(7): 963-971, 2004

Amino acid and peptide conjugates of protoporphyrin: preparation and analysis by high-performance liquid chromatography, high-performance liquid chromatography/electrospray ionization mass spectrometry and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Rapid Communications in Mass Spectrometry 16(17): 1675-1679, 2002

Characterization of glutathione conjugates of pyrrolylated amino acids and peptides by liquid chromatography-mass spectrometry and tandem mass spectrometry with electrospray ionization. Journal Of Chromatography B. 688(2): 187-196, 1997

Characterization of proanthocyanidins from Parkia biglobosa (Jacq.) G. Don. (Fabaceae) by Flow Injection Analysis-Electrospray Ionization Ion Trap Tandem Mass Spectrometry and Liquid Chromatography/Electrospray Ionization Mass Spectrometry. Molecules 18(3): 2803-2820, 2013

Identification of phosphorylated proteins from thrombin-activated human platelets isolated by two-dimensional gel electrophoresis by electrospray ionization-tandem mass spectrometry (ESI-MS/MS) and liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS). Electrophoresis 19(6): 1015-1023, 1998