Stability-indicating first-derivative spectrophotometric determination of furazolidone

A first derivative (1D) spectrophotometric method is described for the determination of furazolidone in the presence of its degradation product (5-nitrofuraldehyde). The method was based on the direct measurement at the maximum of the first derivative curve for furazolidone at 390 nm, which is the zero crossing point of 5-nitrofuraldehyde thus avoiding interference from the degradation product. 5-Nitrofuraldehyde was determined after thin-layer chromatographic separation using silica gel G254 as the coating substance, and mixture of toluene and 1.4-dioxan (95:5) as the developing system. After separation, furazolidone content and its degradation product, 5-nitrofuraldehyde, could be determined separately by first-derivative spectrophotometry at 390 and 290 nm, respectively. 2.5-25 micrograms ml-1 of furazolidone and 5-nitrofuraldehyde could be determined by this method with good accuracy. The proposed method was successfully applied to determine furazolidone in its tablets and 5-nitrofuraldehyde in expired tablets. The results obtained were in good agreement with those obtained by the official method.