Detection and Quantitation of Eicosanoids by Combined Gas Chromatography-Mass Spectrometry

Abstract

Mass spectrometry is an indispensable analytical technique in studies of the metabolism of arachidonic acid to prostaglandins, leukotrienes, and other related eicosanoids. In addition to providing qualitative information, mass spectrometry is recognized as the quantitative analytical technique offering the greatest degree of sensitivity, selectivity, precision, and accuracy in the measurement of very small quantities of eicosanoids in biological samples. Recent adaptations, including (a) the use of a capillary gas Chromatograph interface with the mass spectrometer and (b) the use of negative-ion chemical ionization mass spectrometry of electron-capture derivatives of eicosanoids have facilitated the capability to detect 0.2 picograms (approximately 10–12 moles) and less of these compounds in samples of biological origin. The principles and use of combined capillary gas chromatography-mass spectrometry for subpicogram detection and quantitation of eicosanoids of biological origin are presented. Presently, these techniques have permitted the detection and quantitation of prostaglandins D2, E2, F2α 6-keto-prostaglandin F1α (6KPGF1α), and thromboxane B2 and the 15-keto-13, 14-dihydro metabolites of PGE2, PGF2α, and 6KPGF1α in biological samples. Also, the use of GC-mass spectrometry for simultaneous determinations of the profile and kinetics of prostaglandin biosynthesis and metabolism in isolated tissues and in cultured cells is featured. The use of alternative interface systems of mass spectrometers as they relate to the chemistry and inherent lability of biologically derived eicosanoids is also addressed.