Green micellar factorial design optimized first derivative synchronous spectrofluorimetric method for tripelennamine and diphenhydramine determination in pharmaceutical gel.

A green micellar synchronous spectrofluorimetric method was developed and validated for simultaneous determination of tripelennamine hydrochloride and diphenhydramine in bulk and combined pharmaceutical formulation. Synchronous fluorescence of tripelennamine hydrochloride and diphenhydramine was determined using Δλ = 60 nm. The first derivative of synchronous fluorescence was computed to resolve overlap in the synchronous fluorescence spectra. Tripelennamine hydrochloride was quantified at 375 nm, whereas diphenhydramine was quantified at 293 nm; each is the zero-crossing point of the other. As diphenhydramine exhibited weak native fluorescence, micelle enhancement upon incorporation of sodium dodecyl sulfate was considered. Two-level full factorial design was carried out to optimize experimental parameters. Optimum conditions involved using SDS (2% w/v) along with Teorell and Stenhagen buffer (pH 9). The method was found to be linear over the range 0.2-4.5 and 0.2-5 μg/mL for tripelennamine and diphenhydramine, respectively, with limits of detection 0.211 and 0.159 μg/mL. The method was successfully applied for simultaneous determination of tripelennamine hydrochloride and diphenhydramine in laboratory-prepared gel containing all possible excipients with mean percent recoveries ±SD 100.59 ± 0.79 and 98.99 ± 0.98 for tripelennamine hydrochloride and diphenhydramine, respectively. The proposed method was proved to be eco-friendly using different greenness assessment tools.