Mass spectrometric investigations on estrogen glucuronides) (Abstract only

Recently various methods have been described which make use of combined gas chromatography/mass spectrometry (GC/MS) for the determination of steroids in body fluids. In the course of our studies on the occurrence and metabolism of phenolic steroids in man it became necessary to synthesize and to investigate by MS the following estrogen glucuronides (gluc): estrone 3-gluc estradiol-17beta 3-gluc estradiol-17beta 17beta-gluc estriol 3-gluc estriol 16alpha-gluc 2-hydroxyestradiol-17beta 2-gluc 2-methoxyestradiol-17beta 3-gluc and 2-hydroxy 3-methoxyestradiol-17beta 2-gluc. MS of the free glucuronides did not reveal characteristic fragment ions. This is in accordance with the results obtained with carbohydrates and their derivatives; mass spectra of these compounds rarely show a peak of the molecular ion. However after silylation of the hydroxyl groups of the estrogen glucuronides the mass spectra had typical patterns. All spectra exhibited molecular ions with relatively high intensity; it is noteworthy that in ring D-glucuronides the intensities were about 100-fold greater than in ring A-glucuronides. Fragmentation also allowed a definite discrimination between aromatic (ring A) and aliphatic (ring d) glucuronides. The main fragment of the entire pertrimethylsilylated glucuronic acid moiety of ring D glucuronides was 465 and that of ring A-glucuronides 464. Furthermore aromatic glucuronides yielded a fragment of M-392 which represents the aglycone moiety and 1 additional TMS group from glucuronic acid. Aliphatic glucuronides do not show this phenomenon but form a fragment of M-481 due to the loss of the glucuronic acid moiety together with the glycoisidic oxygen. (full text)