HPLC-DAD stability indicating determination of nitrofurazone and lidocaine hydrochloride in their combined topical dosage form

In this work, a simple, rapid, and selective high-performance liquid chromatography (HPLC) method with diode array detection was developed for the simultaneous determination of nitrofurazone (NZ) and lidocaine hydrochloride (LD). The chromatographic separation was achieved by using Zorbax Eclipse XDB-C18 (4.6 × 150 mm, 5 μm p.s.) analytical column and a mobile phase composed of 0.025 M disodium hydrogen phosphate- methanoltriethylamine (70:30:0.1, v/v/v) (pH 4.0) at a flow rate of 1 mL/min. The detector was set at wavelengths 374 and 220 nm for NZ and LD, respectively, and quantification of the analytes was based on measuring their peak areas. The retention times for NZ and LD were ∼ 4.5 and 5.7 min, respectively. The reliability and analytical performance of the proposed HPLC procedure were statistically validated with respect to system suitability, linearity, ranges, precision, accuracy, selectivity, robustness, and detection and quantification limits. The linear dynamic ranges were 0.5-25 and 2.5-100 μg/mL for NZ and LD, respectively, with correlation coefficients > 0.999. The stability-indicating aspects of the proposed method were demonstrated by the resolution of the two analytes from the related substance and potential impurity (2,6-dimethylaniline) as well as from forced-degradation products. The validated HPLC method was successfully extended to the analysis of the combined topical dosage form (soluble dressing) where no interfering peaks were encountered from the dosage form matrix or the inactive ingredients.