Determination of Paracetamol in Presence of Ascorbic Acid in Pharmaceutical Products by Scanning Electrochemical Microscopy

The selective amperometric determination of paracetamol in pharmaceutical formulations containing ascorbate was achieved by removing the interfering species in the diffusion layer created between a platinum substrate and a disc microelectrode in a Scanning Electrochemical Microscopy (SECM) configuration, while the target analyte was kept unconsumed. After complete depletion of ascorbate, paracetamol was detected at the SECM tip in a free-interference solution zone. The influence of the substrate potential and the gap distance on the efficiency of ascorbate removal was systematically examined. The effectiveness of the device towards the determination of paracetamol in pharmaceutical samples was evaluated and under optimal conditions the results obtained agreed well with the labeled value.