STABILITY INDICATING GREEN ANALYTICAL GAS CHROMATOGRAPHY METHOD FOR THE DETERMINATION OF DIPHENHYDRAMINE IN PURE AND MARKETED FORMULATIONS

The current work defines development of a simple, rapid and precise method based on gas chromatography coupled with Flame Ionization Detector (GC-FID) for the quantitative estimation of diphenhydramine (DPH) present in the marketed formulations following the principles of green analytical chemistry. The analysis was performed using Zebron Phase: ZB-DRUG-1 column with Nitrogen as a carrier gas having a flow rate of 1 ml/min. The injection volume was 1 µL and with the split ratio of 1:10. The retention time of the drug was found to be 4.5 minutes. The developed method was validated according to the ICH guidelines, proving the method to be sensitive towards the analyte with accuracy (mean recovery = 98%), linearity in the range of 2-10 µg/ml (r² 0.993), precision (intraday = 1.118% RSD, interday = 1.16 % RSD), LOD 0.2 µg/ml and LOQ 0.5 µg/ml. The degradation study showed that the drug remains stable in acid, base, neutral, oxidation, and photolytic method. The developed method can be effectively employed for the day to day analysis of DPH in pure and marketed formulations by industries and not so well equipped laboratories, as the method employs direct analysis of DPH without any derivatization technique by gas chromatography with simple flame ionization detection.