Mass fragmentography as reference method in clinical steroid assay

Abstract

Mass fragmentography may serve as a powerful tool in the fields of steroid biochemistry and clinical chemistry; it provides a simple and highly specific method for the determination of steroids in body fluids. Isotopically labelled steroids, corresponding to the natural occurring steroids, may be used as internal standards in order to correct for procedural losses as well as adsorption effects on the gas Chromatographie columns. Since the mass spectrometer is capable of separating isotopes, quantitative determinations may be performed by comparing the peak areas of the unlabelled and the isotopically labelled steroids; the peaks are recorded simultaneously by monitoring two m/e- values (multiple ion detection). With respect to sensitivity and specificity, the method may be considerably improved by the use of special derivatives, e.g. heptafluorobutyrates. Because of their high specificity, determinations by mass fragmentography will be increasingly used as reference methods in the field of steroid hormones. In the present paper the procedure has been applied to the specific determination of oestrogens, testosterone, 5α-dihydrotestosterone, cortisol and aldosterone in human plasma.