Some Observations on Hydrolysis of Oestrogen Conjugates in Bovine Urine

Abstract

Oestratetraenol is an artifact arising from oestradiol-17α during acid hydrolysis of bovine urine. This finding led us to investigate the influence of acid concentration and time of heating on the yield of these two substances as compared with enzyme hydrolysis. For oestradiol-17α enzyme hydrolysis resulted in a 5 to 6 times higher yield than acid hydrolysis (6 vol.% HCl. 1 hour at 100° C). The results being the same whether the starting material was natural urine or previously extracted conjugates. When acid hydrolysis was used as mentioned above, the conversion of pure oestradiol-17α to oestratetraenol was of the order of 10 to 15%. In view of the extreme lability of oestradiol-17α to acid hydrolysis and its partial transformation to oestratetraenol, the problems of acid hydrolysis of bovine urinary oestrogen conjugates are discussed.

Reply to comment on “Isolation and detection of steroids from human urine by molecularly imprinted solid-phase extraction and liquid chromatography” by Tse Sum Bui and Haupt [J. Chromatogr. B 877 (2009) 4180–4181]

“…Hydrolysis is strongly influenced by several parameters including the type of acid employed (i.e., hydrochloric acid, sulphuric acid), acid molarity, temperature, and the time of reaction [3,4]. Hence, an analysis of these hormones in urine requires complete hydrolysis of the known conjugates and sulphates.…”

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Reply to comment on "Isolation and detection of steroids from human urine by molecularly imprinted solid-phase extraction and liquid chromatography" by Tse Sum Bui and Haupt [J. Chromatogr. Hydrolysis is strongly influenced by several parameters including the type of acid employed (i.e., hydrochloric acid, sulphuric acid), acid molarity, temperature, and the time of reaction [3,4]. Hence, an analysis of these hormones in urine requires complete hydrolysis of the known conjugates and sulphates.

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