IMPROVED EXTRACTION PROCEDURE FOR THE ASSAY OF ISOSORBIDE-5-MONONITRATE IN SERUM

A procedure is described for the extraction of isosorbide-5-mononitrat e from serum with diethyl ether-n-butyl acetate (15:1, v/v). After ext raction, the diethyl ether is evaporated at room temperature and the n itrate remains dissolved in the relatively non-volatile n-butyl acetat e phase. Glassware must be used throughout as the recovery of isosorbi de-5-mononitrate is not reproducible when plastic tubes or plastic pip ettes are used. The extraction recovery of isosorbide-5-mononitrate fr om serum is 67+/-7%, measured relative to external standards.