Quantification of urinary 8-iso-prostaglandin F2alpha using liquid chromatography-tandem mass spectrometry during cardiac valve surgery

Oxidative stress is an unavoidable event during many complex surgical procedures. 8-iso-prostaglandin F(2alpha) (8-iso-PGF(2alpha)) is a reliable biomarker for the evaluation of oxidative stress in vivo. The aim of this study is to develop simple and accurate liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods for the detection of urinary 8-iso-PGF(2alpha) in samples collected from patients who received a cardiopulmonary bypass (CPB) during cardiac valve surgery. Urine samples of 14 patients with cardiac valve diseases were collected before, during, and after CPB. The level of 8-iso-PGF(2alpha) was detected via selected-reaction monitoring triple quadrupole MS/MS and the result was compared with 12 healthy volunteers. The method's detection limit (3S/N) was 0.25 pg for 8-iso-PGF(2alpha), with a linear working range of 0.25-20 ng/ml. For patients with cardiac valve disease, the 8-iso-PGF(2alpha) levels before the bypasses were the same as those of healthy individuals (P>0.05) and the 8-iso-PGF(2alpha) levels during and after CPB were significantly higher than those before the bypasses (P<0.05). In conclusion, we present a simple and specific protocol for LC-MS/MS quantification of urinary 8-iso-PGF(2alpha) collected during CPB. Using this technique, it would be feasible to assess the levels of oxidative stress during cardiac surgery and thereby helpful for the management of oxidative injury.