Colorimetric Method for Determination of Guanazole in Blood and Urine

A colorimetric method, based on diazotization and coupling, for the determination of guanazole in aqueous solution, blood, and urine is described. The average relative standard deviation of the method is about 0.9%. Determination in blood involves precipitation of proteins with trichloroacetic acid and diazotization and coupling of guanazole in the filtrate. Determination in urine involves separation of guanazole from the diazotizable, naturally occurring urinary aromatic amines using ion-exchange chromatography.