Primaquine Phosphate as a Promising Substitute for N-(1-Naphthyl)ethylenediamine. II. Analysis of Sulfa Drugs in Pharmaceutical Dosage Forms and Biological Samples.

Abstract

A simple and sensitive spectrophotometric method for the determination of sulfonamides in bulk, in pharmaceutical dosage forms and in biological fluids was developed. The method is based on coupling the diazotized sulfa with the anti-malarial ingredient, primaquine phosphate, in an acid medium. The resulting orange color is stable for several weeks and has an absorption maximum between 468 - 474 nm, depending on the sulfa drug. The effect of different variables on color development was studied. Calibration graphs were established in the concentration range of 0.1 to 12 µg/ml with a minimum detection limit of 0.05 µg/ml. The molar absorptivities were in the range of 47589 - 66414 l mol-1 cm-1 , depending upon the sulfa drug. The percentage recoveries of sulfa drugs in dosage forms were in the range of 97.4 to 104.0%. The method was also utilized in the determination of sulfamethoxazole and N-acetyl sulfamethoxazole in serum and urine samples.