Spectrofluorimetric and Spectrophotometric Determination of Oxamniquine in Pharmaceuticals and Biological Fluids via Derivatization with 4-Chloro-7-Nitrobenzo-2-oxa-1,3-Diazole (NBD-Cl)

Spectrophotometric and spectrofluorimetric methods were developed for the determination of oxamniquine (OXM). Both methods are based on coupling with 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl) in borate buffer of pH 7.6, and the reaction product was measured at 400 nm (Method I). The same product was measured by spectrofluorimetry at 480 nm upon excitation at 400 nm (Method II). The absorbance and the fluorescence intensity were enhanced by addition of sodium dodecyl sulphate (SDS). The absorbance-concentration plot is rectilinear over the range of 5-25 μg/mL with an LOD of 0.31 μg/mL. The fluorescence-concentration plot is linear over the range of 0.2-1.2 μg/mL with an LOD of 0.03 μg/mL. Both methods were applied to the analysis of capsules, and the results were in good agreement with those obtained using the official method. The method was applied to spiked human plasma; the mean % recovery (n = 5) is 101.05 ± 1.65. A proposal of the reaction pathway is presented.