Fast sequential determination of amoxicillin and clavulanate in pharmaceutical samples using batch injection analysis with amperometric detection

The combination of amoxicillin (AMX) and clavulanic acid (CLA) is one of the most widely used antibiotic medicines in the world. This paper describes a novel electrochemical method for the fast sequential determination of AMX and CLA using batch injection analysis with amperometric detection (BIA-AD) and boron-doped diamond (BDD) as the working electrode. In the proposed strategy, AMX was selectively detected at +1.3 V and both compounds (AMX+CLA) at +1.8 V. The oxidation current from CLA was accessed by subtracting the currents detected at both potential pulses (i+(1.8 V)-i+(1.3V)) and using a simple correction factor. The developed method proved to be simple, cost-effective, precise (RSD<1.3 %, n=10), rapid (>200 injection h(-1)), required simple sample preparation steps (dissolution and dilution only) and can be used in laboratories with minimal infrastructure (portable characteristics). The limits of detection were 0.31 (0.13) and 1.99 (0.47) mu mol L-1 (mg L-1) for AMX and CLA, respectively. The results obtained by the proposed BIA-AD method were comparable to those obtained by capillary electrophorese (95 % confidence level).