Determination of Urinary F2-Isoprostanes as an Oxidaitve Biomarker in Patients with Diabetes Mellitus Type 2 by Liquid Chromatography-Electrospray Tandem Mass Spectrometry

Abstract

A liquid chromatography tandem mass spectrometry (LC-MS/MS)-ion trap coupled with electrospray ionization was described for determination of trace biological molecular, urinary F₂-Isoprostanes (F₂-IsoPs), a sensitive biomarker of oxidative stress in vivo, in Thai patients with diabetic mellitus (DM) type 2 and compare with normal subjects. Spot urine samples were collected from 28 DM patients and 19 normal subjects and extracted by solid-phase extraction prior to injection onto the LC system. The analytical method was validated with limit of quantification (LOQ) of 200 pg/ml, good linearity was obtained in the range of 200-20,000 pg/ml (r = 0.9992) and recoveries at 400-10,000 pg/ml were 77-102%. The levels of F₂-IsoP in urines from DM patients were 720.37 ± 454.89 pg/mg creatinine (mean ± SD) whereas the levels in normal subjects were 375.08 ± 440.64 pg/mg creatinine (mean ± SD). It is worth noting that urine samples from 8 out of 19 normal subjects contained urinary F₂-IsoPs at the level below LOQ (200 pg/ml). This study demonstrated an alternative method by LC-MS/MS ion trap method for determination of F₂-IsoPs in urine as a sensitive biomarker.