Spectrofluorimetric determination of oxamniquine in dosage forms and spiked human plasma through derivatization with 1-dimethylaminonaphthalene-5-sulphonyl chloride.

A sensitive, simple and selective spectrofluorimetric method was developed for the determination of oxamniquine (OXM) in pharmaceutical formulations and biological fluids. The method is based on the reaction between the drug and 1-dimethylaminonaphthalene-5-sulphonyl chloride (dansyl chloride) in presence of 0.5 M sodium carbonate (pH 10) to yield a highly fluorescent derivative that is measured at 445 nm after excitation at 335 nm. The different experimental parameters affecting the development and stability of the reaction product were carefully studied and optimized. The fluorescence concentration plot was rectilinear over the range of 0.02-0.2 microg ml(-1) with a lower detection limit (LOD) of 0.007 microg ml(-1) and limit of quantitation (LOQ) of 0.02 microg ml(-1). The proposed method was successfully applied to the analysis of commercial capsules. The results obtained were in good agreement with those obtained using the official spectrophotometric method. Furthermore, the method was applied for the determination of oxamniquine in spiked human plasma, the mean % recovery (n = 4) is 97.77 +/- 1.19. A proposal of the reaction pathway was presented.