Abstract
In the presented work, potassium dichromate in the presence of sulfuric acid was used as a reagent for spectrophotometric determination of imipramine HCl concentration in tablet formulations. The variables of the proposed method such as volume of potassium dichromate (0.01%), volume of sulfuric acid (10 M) and concentration of imipramine HCl (µg mL−1) were optimized by response surface methodology via Box-Behnken design. The optimum conditions were 14 µg mL−1 of imipramine HCl, 0.6 mL of 0.01% potassium dichromate and 5.0 mL of 10 M sulfuric acid. The green coloured product (dimeric compound of imipramine HCl) absorbed maximally at 620 nm. The stoichiometric ratio between imipramine HCl and potassium dichromate was studied by mole ratio method and found to be 2:1. The formation constant (Kf) and apparent Gibb’s free energy (ΔG°) were calculated and found to be 1.858 × 1014 and −81.182 kJ mol−1, respectively. Beer’s law was obeyed in the imipramine HCl concentration range of 1–14 μg mL−1 with molar absorptivity of 2.25 × 104 Lmol−1 cm−1. The proposed method was successfully applied for the determination of imipramine HCl concentration in tablet formulations (solid materials) and statistically found to be in good agreement with the reference method. The % recovery of proposed and reference methods was in the range of 99.94–100.08% and showed the compliance (100 ± 2%) with regulatory guidelines.