Quantifying F2-isoprostanes in umbilical cord blood of newborn by gas chromatography-mass spectrometry

We attempted to improve the extraction procedures to determine the F-2-isoprostanes in plasma of umbilical cord arterial and venous blood by gas chromatography mass spectrometry. Plasma samples were deproteinized and hydrolyzed; free and esterified F-2-isoprostanes were extracted by solid-phase extraction columns with citric acid/methanol/cyclohexane and ammonia solution/methanol and then derivatized by PFBBr and BSTFA. Concentrations of total plasma F-2-isoprostanes eluted at the retention time of an internal standard of 8-iso-prostaglandin F-2alpha-D-4 were quantified. The absolute recovery was 83 +/- 1.9% (95% confidence). Intraassay precision and interassay precision were lower than 1.0%. Analytical accuracy was 99.0 +/- 0.4% (95% confidence). Linearity, r(2), over the concentration range of 10 to 5000 pg/ml of spiked 8-iso-prostaglandin F-2alpha in plasma was 0.9985. The method detection limit was 21 pg/ml (99% confidence) and the limit of quantitation was approximately 4 pg/ml. Analysis of 200 neonatal cord blood samples revealed few overlapping peaks causing interference in the elution of the F2-isoprostanes. With the use of an autosampler and one technician, 48 samples can be completed within 24 h with 6 h of actual hands-on work. This method could be potentially employed for routine analysis of plasma F-2-isoprostancs in clinical laboratories. (C) 2003 Elsevier Science (USA). All rights reserved.