Electrochemical stability of metformin in NaHCO3 and Na2SO4 water solution at Au, GC and IrOx electrodes

In this study the electrochemical behavior of metformin (MET), oral antihyperglycaemic agent, was assayed at three different electrodes. The drug standard was investigated by cyclic voltammetry and square wave voltammetry via its electrooxidation at Au and glassy carbon electrode in 0.05 M NaHCO3. Under these conditions transformation of MET to corresponding N-carbonyl guanidine via oxime intermediate is suggested. The stability of MET was tested under directed stress conditions using IrOx electrode with sodium sulphate as an electrolyte and cyclic 4-amino-2-imino-1-methyl-1,2-dihydro-1,3,5-triazine appeared as the main end-product. The courses of the electrochemical processes at three electrodes were followed by UV spectroscopy and evaluated by total organic carbon analysis.