Abstract

This work presents a fast spectrophotometric method for measuring metformin in bulk and pharmaceutical forms. The method uses the oxidative coupling of metformin with 3-methyl-2-benzthiazolinone hydrazone (MBTH) in the presence of ferric chloride, producing a stable green chromophore that absorbs best at 615 nm. Key experimental factors, including reagent levels and addition sequence, were optimized. The calibration curve showed a linear range of 1–16 μg/mL (r = 0.9991), with a molar absorptivity of 3.32×104 L·mol−1·cm−1. Detection and quantification limits were 0.0089 and 0.040 μg/mL, respectively. Accuracy and precision tests indicated excellent recovery rates (99.87–99.99%) and low RSD (<0.1%). The method successfully applied to pharmaceutical preparations. Compared to existing UV and HPLC methods, this it offers advantages in simplicity, sensitivity, and cost-effectiveness, eliminating the need of pretreatment. This technique may serve as a reliable tool for routine quality control of metformin products as an environmentally friendly alternative.

Keywords: metformin, spectrophotometry, MBTH, ferric chloride, oxidative coupling, pharmaceutical control

Article language: En