DETERMINATION OF DEHYDROEPIANDROSTERONE-SULFATE IN HUMAN PLASMA BY GAS-CHROMATOGRAPHY MASS-SPECTROMETRY USING A DEUTERATED INTERNAL STANDARD - A METHOD SUITABLE FOR ROUTINE CLINICAL USE

A capillary gas chromatographic-mass spectrometric method for the dete rmination of dehydroepiandrosterone sulfate (DHEA-S) in human plasma i s described. [7,7-H-2(2)]DHEA-S is used as internal standard. After de sulfation by methanolysis, heptafluorobutyryl derivatives are prepared , and selected ion monitoring of characteristic fragment ions - m/z 27 0 for DHEA and m/z 272 for [7,7-H-2(2)]DHEA - is carried out. Requirin g small amounts of plasma, the rapid, convenient work-up and the appli cation of bench-top GC/MS instrumentation proved our method to be suit ed for routine clinical use in adults and children. The method needs n o complex corrections for isotope contributions and provides good accu racy and precision. Comparative values of samples assayed by our GC/MS procedure and by a direct RIA indicated that the RIA overestimates th e true concentration.