Quantification of Thiazolidine-4-carboxylic Acid in Toxicant-Exposed Cells by Isotope-Dilution Liquid Chromatography–Mass Spectrometry Reveals an Intrinsic Antagonistic Response to Oxidative Stress-Induced Toxicity

2014 ◽  
Vol 28 (3) ◽  
pp. 394-400 ◽  
Author(s):  
Jingjing Liu ◽  
Wan Chan
Keyword(s):  
Oxidative Stress ◽  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Carboxylic Acid ◽  
Isotope Dilution ◽  
Liquid Chromatography Mass Spectrometry ◽  
Chromatography Mass Spectrometry

scholarly journals Quantification of Serum and Urinary S-Adenosylmethionine and S-Adenosylhomocysteine by Stable-Isotope-Dilution Liquid Chromatography-Mass Spectrometry

2004 ◽  
Vol 50 (2) ◽  
pp. 365-372 ◽  
Author(s):  
Sally P Stabler ◽  
Robert H Allen
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Stable Isotope ◽  
Isotope Dilution ◽  
Biological Fluids ◽  
Internal Standard ◽  
Fractional Excretion ◽  
Liquid Chromatography Mass Spectrometry ◽  
Stable Isotope Dilution ◽  
Chromatography Mass Spectrometry

Abstract Background: We have developed an assay that uses stable-isotope-dilution liquid chromatography–mass spectrometry to assess S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) in body fluids to investigate the relationship of these metabolites to hyperhomocysteinemia. Methods: Commercially obtained SAM (D3 methyl) and 13C5-SAH uniformly labeled in the adenosyl moiety, which was synthesized using S-adenosylhomocysteine hydrolase, were added to samples followed by perchloric acid protein precipitation, C18 chromatography, and analysis by liquid chromatography–mass spectrometry with quantification by comparison of the areas of internal standard and endogenous peaks. Results: Estimates of intraassay imprecision (CV) were 5% and 17% for SAM and SAH, respectively (n = 10). SAM decreased and SAH increased in serum and plasma samples at both 4 °C and room temperature over 80 h. SAM and SAH were unstable in samples stored longer than 2 years at −20 °C. In 48 volunteers, the estimated reference intervals [from mean (2 SD) of log-transformed data] for serum SAM and SAH were 71–168 and 8–26 nmol/L, respectively. Fractional excretion of SAM was higher than that of SAH, and the urinary SAM:SAH ratio was much higher than the serum or erythrocyte SAM:SAH ratios. Conclusions: Stable-isotope-dilution liquid chromatography–mass spectrometry can be used to quantify SAM and SAH in biological fluids and tissues. Sample handling and storage must be stringently controlled for any epidemiologic or clinical use of such assays.

Confirmatory Identification of Carbadox-Related Residues in Swine Liver by Gas-Liquid Chromatography/Mass Spectrometry with Selected Ion Monitoring

1982 ◽  
Vol 65 (1) ◽  
pp. 66-70 ◽  
Author(s):  
Martin J Lynch ◽  
S Richard Bartolucci
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Carboxylic Acid ◽  
Gas Liquid Chromatography ◽  
Target Tissue ◽  
Liquid Chromatography Mass Spectrometry ◽  
Selected Ion Monitoring ◽  
Methyl Ester Derivative ◽  
Chromatography Mass Spectrometry ◽  
Swine Liver

Abstract A confirmatory method has been developed to identify quinoxaline-2-carboxylic acid, the carbadox tissue residue, in swine liver, a target tissue, at the regulatory level of 30 μg/kg. Quinoxaline-2-carboxylic acid (QCA) is isolated from liver hydrolysates by solvent extraction and ion-exclusion chromatography, and a methyl ester derivative (CP-25,536 or QME) is identified by gas-liquid chromatography/ mass spectrometry with selected ion monitoring. The relative intensities of 3 ions: the base peak at m/z = 130, a second significant mass at m/z = 158, and the molecular ion (M+) at m/z = 188, are monitored simultaneously with a quadrupole mass spectrometer. Validation studies consisting of the analysis of liver fortified with QCA at the regulatory level and analysis of swine specimens containing physiologically incurred carbadox residues demonstrated that peak height ratios of ions in these tissue extracts corresponded to ion intensities of standards monitored at m/z = 188,158, and 130.

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