QUANTITATIVE MEASUREMENT OF 4-HYDROXYALKENALS IN OXIDIZED LOW-DENSITY-LIPOPROTEIN BY GAS-CHROMATOGRAPHY MASS-SPECTROMETRY

Previously, we reported on the determination of 4-hydroxyalkenals as p entafluorobenzyl oxime derivatives by gas chromatography-mass spectrom etry. In this study, an improved method is presented which allows quan titative detection of 4-hydroxyalkenals in tissues by using two stable isotope-labeled internal standards, 9D(3)-4-hydroxynonenal and 9D(3)- 4-hydroxyhexenal. This assay was used to quantitate 4-hydroxyalkenals in copper-oxidized human low-density lipoprotein, and we found more 4- hydroxynonenal than 4-hydroxyhexenal. This is consistent with the fact that there are more omega-6 than omega-3 fatty acids in human low-den sity lipoprotein samples, which are the sources of 4-hydroxynonenal an d 4-hydroxyhexenal, respectively. (C) 1995 Academic Press, Inc.