Investigation of Electrochemical Behavior of Bilirubin at Unmodified Carbon Paste Electrode

Bilirubin is predominantly formed in the liver as a result of breakdown of hemoglobin. Knowing the concentration of bilirubin in serum is important in evaluating the health of the liver, and for the diagnosis of hyperbilirubinemia (a condition that afflicts approximately 60% of full term and 80% of pre-term newborns). In this work, a carbon paste electrode (CPE) has been used to study the electrochemical oxidation of bilirubin (BR) and its feasibility to be performed at unmodified or untreated carbon paste in an effort to propose a simple voltammetric method for detection of bilirubin. Irreversible oxidation of BR at CPE had occurred at about +0.32 V vs. Ag/AgCl as a diffusion-controlled process, when suitable pH for this redox transformation was either a mild alkaline solution (of Phosphate buffer, pH 8) or a neutral supporting medium. After having chosen the DPV mode and optimizing the electroanalytical parameters, the oxidation responses of the analyte has been justly proportional to concentration in the range of 3.5–25 μmol. L-1 with LOD of 1.2 μmol. L-1 in phosphate buffer.