Facile HPLC/Uv Method for Determination of Metformin and 1-Cyanoguanidine Using Novel Halogenated Stationary Phase

Abstract

Metformin is the most prescribed drug for diabetes. We aimed to develop a new HPLC method for determination of metformin and its main impurity 1-cyanoguanidine in raw material and its pharmaceutical tablets. The separation was achieved on pentabromobenzyl column using a mixture of 20% 10.0 mM phosphate buffer (pH 5.5) and 80% methanol as a mobile phase at a flow rate of 1.0 mL min -1 and UV detection at 227 nm. The analysis time was less than 4.0 minutes. The method was linear through concentration ranges of 3.0 -80 µg mL -1 and 0.5-10 µg mL -1 and detection limits of 0.73 µg mL -1 and 0.11 µg mL -1 for metformin and 1cyanoguanidine, respectively. The method was successfully applied for determination of metformin in bulk and pharmaceutical dosage forms. The high sensitivity of the developed method allowed for determination of 1-cyanoguanidine below its specified limits in metformin raw material and tablets.