SPECTROPHOTOMETRIC DETERMINATION OF BIOACTIVE COMPOUNDS IN COMMERCIALSAMPLES WITH NITROUS-ACID AND CRESYL FAST VIOLET ACETATE

A simple and sensitive method for the spectrophotometric determination of bio-active compounds (drugs and non-nutritive sweeteners) containi ng reactive functional groups, viz., aromatic primary amine (drugs: Su lphamethoxazole), aromatic secondary amine (drug: Pindolol), secondary amine (non-nutritive sweetener: Cyclamate), acid hydrazide (drug: Iso niazid) and thiol (drug: Captopril), is proposed. The method involves the addition of excess of sodium nitrite to the compound in the presen ce of 0.25 M hydrochloric acid solution and the unreacted nitrous acid is determined by the measurement of corresponding decrease in the abs orbance of cresyl fast violet acetate (lambda(max) : 555 nm), the most suitable one out of several dyes tested, This method was applied for the determination of bio-active compounds in commercial samples. (drug s: pharmaceutical formulations; non-nutritive sweetener (cyclamate): f oodstuffs). The newly proposed method enabled the determination of the bio-active compounds in microgram quantities (0.1 - 0.5 mu g/ml). Sta ndard deviation values evaluated through replicate determinations were found to be < 0.5 mg per dose (RSD : 0.5 - 1.2%). The common excipien ts do not effect the determination of the drugs in pharmaceutical form ulations. Many of the usually occurring additives in food stuffs are t olerated to a very high level in the determination of cyclamate in bev erages, syrup, ice candy and ice cream. The validity of the method was tested against the reference method. Recoveries to the tune of 99.2 - 101.1% were observed by adopting this method.