Publisher Summary This chapter discusses the newer approaches to the isolation, identification, and quantitation of steroids in biological materials. Progress in steroid analysis has been remarkable in the last 15 years. Much of present knowledge in steroid endocrinology could not have been acquired without the development of radioimmunoassay and other competitive protein-binding methods. These methods have provided the sensitivity and speed required for measurement of physiological concentrations of steroid hormones in large series of samples. Parallel with this development, both liquid and gas-liquid chromatographic methods have been markedly improved and mass spectrometers have become available for routine use. The most important advancement in this area has been the successful combination of gas chromatography and mass spectrometry (GC-MS) for analysis of molecules as large as steroids. Immunoassay and GC-MS are complementary methods. GC-MS is important as a reference method to test and validate the specificity of an immunoassay. The steroid composition of biological samples taken under different physiological and pathological conditions can be characterized by GC-MS, and immunoassays may then be developed for detailed studies of selected steroids in larger numbers of samples.

Newer approaches to the isolation, identification, and quantitation of steroids in biological materials.

Mass Spectrometry and the Stereochemistry of Organic Molecules

An easy determination of epimeric androsterones by collision spectroscopy: the molar ratio of 5β‐androstan‐3α‐ol‐17‐one and 5β‐androstan‐3β‐ol‐17‐one obtained by hydrogenation of 5β‐androstan‐3,17‐dione on Cu/Al2O3 58‐Androstan‐3,17‐dione on Cu/A1203

The mass spectrometric behaviour of ring A substituted allobetulane derivatives is discussed. The position and nature of a substituent both influence the mass spectral decomposition remarkably. In the case of the epimeric 1-hydroxy- and acetoxy allobetulanes, the mass spectral differences are great enough to distinguish these from each other. The results should yield a general rationalization for other saturated triterpenes having the same A, B, C ring system.

Mass spectroscopy of natural products. V—Mass spectroscopic studies of ring a substituted allobetulane derivatives

The mass spectra of androstan-3,16,17beta-triols are very similar, so that a distinction between isomers is rather difficult. Main degradation reactions correspond to expulsion of substituents and loss of parts of the D-ring system.

Location of functional groups with the aid of mass spectrometry. XVI.--Mass spectra of trimethylsilylated androstan-3,16,17 beta-triols.

Mass spectra of steroids containing a carbonyl group in position 11 and a 3α-hydroxy group in a cis connected A/B ring system are characterised by very strong [M – 72]+· key ions and may therefore be clearly differentiated from the spectra of their isomers. The mechanism of this fragmentation reaction was investigated by deuterium labelling and the DADI technique. The 3α-hydroxy group is eliminated together with the 9α-H atom. Next a hydrogen atom is transferred from the A ring to the B/C/D ring system. This causes the cleavage of the C-3C-4 bond and expulsion of C atoms 1 to 4 as butadiene. In 3α-hydroxy-5α-androstanes possessing no 11-keto group an analogous [M – 18]+. fragment is fromed, followed by the elimination of ethylene originating mostly from C-1 and C-2.

ZUM MECHANISMUS MASSENSPEKTROMETRISCHER FRAGMENTIERUNGSREAKTIONEN BEI A/B‐CIS‐ VERKNüPFTEN 3α‐HYDROXYSTEROIDEN MIT UND OHNE 11‐KETOGRUPPE

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ZUM MECHANISMUS MASSENSPEKTROMETRISCHER FRAGMENTIERUNGSREAKTIONEN BEI A/B‐CIS‐ VERKNüPFTEN 3α‐HYDROXYSTEROIDEN MIT UND OHNE 11‐KETOGRUPPE