The behaviour of the glucuronide derivative of 2'-hydroxymethylmethaqualone with hydrochloric acid was investigated. Three methods of hydrolysis were selected. With method I(12-13% HCl; 30 min at 100 degrees C) about 27% and with method II (20% HCl; 6 min heated azeotrope in open vessel) about 94-95% of the glucuronide derivative was hydrolyzed. With method III (approx. 5% HCl; 30 min at 100 degrees C) only about 3% of the conjugated compound was converted to the free form.