Amperometric nonenzymatic determination of serum glucose by means of a nickel-catalyst electrode

We describe a new, nonenzymatic method for determining serum glucose. This method is based upon the direct electrochemical oxidation of glucose by means of stable nickel-catalyst that is electrodeposited onto a lead dioxide electrode surface. Linear calibration plots are obtained for glucose in the 0.1 to 4500 mg/liter range. Values for 23 sera with glucose concentrations ranging from 300 to 4300 mg/liter showed a linear correlation coefficient of 0.996 when compared with values reported by a hospital laboratory using the hexokinase method. Typically a 25-microliter sample is used, but samples as small as 5 microliter have been successfully analyzed. The sample is added to 25.00 ml of pH 13 electrolyte containing 1 mmol of NiSO4 per liter; the amount of increase in anodic current comproses the analytical signal. For 20 repetitive analyses of a serum specimen, the CV was less than 4%. Ascorbic acid is rapidly decomposed in the electrolyte used and thus does not interfere. Uric acid is inactive at the concentrations present in serum samples. The sensitivity and simplicity of the new method suggest it as an alternative to currently available procedures.