Simultaneous electrochemical determination of the tumour biomarkers homovanillic acid and vanillylmandelic acid using a modified pencil graphite electrode

This study describes the fabrication of an electrochemical sensor for the simultaneous detection of the tumour biomarkers homovanillic acid (HVA) and vanillylmandelic acid (VMA). The electrooxidation of HVA and VMA were studied at a pencil graphite electrode (PGE) modified with an electropolymer of 4-Aminosalicylic acid (ASA). Cyclic voltammetric (CV) studies of HVA and VMA on PGE and poly-ASA modified PGE (PASA-PGE) showed that simultaneous resolution of these analytes was possible only on PASA-PGE. The differential pulse voltammetric (DPV) response of HVA and VMA on PASA-PGE was found to be linear in a concentration range of 3.00 mu M-61.40 mu M and 0.50 mu M -15.35 mu M with a respective lower detection limit (LOD) of 1.82 mu M and 0.28 mu M. This is the first work reporting the electrochemical quantification of HVA and VMA simultaneously on PGE and was analytically applied for the determination of these analytes from human urine samples.