Development of a reliable method based on ultra-performance liquid chromatography coupled to tandem mass spectrometry to measure thiol-associated oxidative stress in whole blood samples.

The aminothiols are biological compounds with numerous vital functions. One of the most relevant is their role as antioxidant systems. The reduced to oxidized ratios are extremely useful indicators of oxidative stress and cellular redox status. We have validated an ultra-high performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS) method to determine the levels of glutathione, cysteine, homocysteine, and their respective oxidized compounds in whole blood samples. Results showed excellent linearity for all the analytes with correlation coefficients between 0.990 and 0.997, suitable precision with intra-day coefficient of variation ≤20%, and satisfactory accuracy with recoveries between 75 and 130%. The limits of detection in whole blood samples were 1.16 nmol L(-1) for glutathione, 115.8 nmol L(-1) for oxidized glutathione, 9.3 nmol L(-1) for homocystine, 92.6 nmol L(-1) for homocysteine, 347 nmol L(-1) for cystine and 0.23 nmol L(-1) for cysteine. The suitability of the method was ascertained in whole blood samples (n=80) from a consolidated experimental model of hypoxia-reoxygenation in newborn piglets.