SIMULTANEOUS DETERMINATION OF MULTIPLE ALDEHYDES IN BIOLOGICAL TISSUES AND FLUIDS USING GAS-CHROMATOGRAPHY STABLE-ISOTOPE DILUTION MASS-SPECTROMETRY

Biological oxidative stress has been associated with various degenerat ive disorders and disease states, and accurate and sensitive methods a re needed to determine the extent of oxidation occurring in vivo. Pero xidation of polyunsaturated fatty acids forms complex mixtures of alde hydes and other breakdown products because various oxidants are involv ed and lipid composition is not uniform. Quantitative analysis of mult iple lipid peroxidation products yields a more complete measure of bio logical oxidation than measurement of a single aldehyde, particularly when aldehydes exhibit marked differences in reactivity. This report d escribes extensions of an established gas chromatography/mass spectrom etry method to include stable isotope dilution determination in tissue and plasma of three aldehydic products of lipid peroxidation: hexanal , nonanal, and 4-hydroxy-2-nonenal. Use of deuterated internal standar ds for each analyte improved precision and accuracy compared to a sing le internal standard for all three aldehydes, Improvements are attribu ted to differences in extraction and derivatization efficiencies for i ndividual analytes owing to substantial differences in reactivity. Ele ctron ionization of oxime-tert-butyldimethylsilyl derivatives gave gre ater specificity for detecting all three aldehydes than was possible u sing electron-capture ionization of O-pentafluorobenzyl oxime derivati ves. Exchange of the deuterium label of [2,3-H-2]HNE internal standard was determined to be minimal during the analyses. (C) 1996 Academic P ress, Inc.