Development and validation of an HPTLC method for the simultaneous estimation of Clonazepam and Paroxetine hydrochloride using a DOE approach

The present study examines simultaneous multiple response optimization using Derringer's desirability function for the development of an HPTLC method to detect Clonazepam and Paroxetine hydrochloride in pharmaceutical dosage form. Central composite design (CCD) was used to optimize the chromatographic conditions for HPTLC. The independent variables used for the optimization were the n-butanol content in the mobile phase, the chamber saturation time and the distance travelled. HPTLC separation was performed on aluminium plates pre-coated with silica gel 60 F254 as the stationary phase using n-butanol:glacial acetic acid:water (9:2:0.5% v/v/v) as the mobile phase. Quantification was achieved based on a densitometric analysis of Clonazepam and Paroxetine hydrochloride over the concentration range of 40-240 ng/band and 300-1800 ng/band, respectively, at 288 nm. The method yielded compact and well-resolved bands at Rf of 0.77 ± 0.02 and 0.34 ± 0.02 for Clonazepam and Paroxetine hydrochloride, respectively. The linear regression analysis for the calibration plots produced r2 = 0.9958 and r2 = 0.9989 for Clonazepam and Paroxetine hydrochloride, respectively. The precision, accuracy, robustness, specificity, limit of detection and limit of quantitation of the method were validated according to the ICH guidelines. The factors evaluated in the robustness test were determined to have an insignificant effect on the selected responses. The results indicate that the method is suitable for the routine quality control testing of marketed tablet formulations.