Optimization Quantitative Determination of Cimetidine in Pharmaceutical Preparations via Bromothymol Blue Using Central Composite Design

Abstract

Optimum conditions for ion-pair complex formation between cimetidine-bromothymol blue (BTB) are determined using central composite design (CCD) by investigating the effects of three experimental factors including pH, reagent concentration and shaking time. The optimum conditions were found to be pH=5.53, %BTB=0.05% and shaking time=5.71 minutes. The linearity dynamic range for cimetidine are (0.5-15) µg.mL-1 at 427.5 nm with detection limit of 0.222 µg.mL-1. The results show the absence of interferences from the excipients on the determination of the above drug. The proposed method has been successfully applied for the determination of cimetidine in pharmaceutical preparations.