The colorimetric estimation of stilboestrol, hexoestrol and their glucuronides in urine.

1. A reinvestigation of the methods for the purification of ox-spleen P-glucuronidase using the variable solvent solubility test has revealed the presence oftwo fractions having different pH optima. The two enzymes have been separated and purified by fractional precipitation with ammonium sulphate and shown to have the foll6wing pH optima: with 1-menthylglucuronide 4-5 and 5 0; phenylglucuronide 4-5 and 5*2; phenolphthalein glucuronide 4-5 and 5-2. 2. Methods of P-glucuronidase assay using 1menthylglucuronnide, phenyiglucuronide andphenol phthalein glucuronide are presented. 3. The relation ofthese results to those ofprevious workers is discussed.