Reduction of the interferences of biochemicals and hematocrit ratio on the determination of whole blood glucose using multiple screen-printed carbon electrode test strips

A practical approach to reduce the interferences of biochemicals and hematocrit ratio (Hct%) in the determination of whole blood glucose using multiple screen-printed carbon electrode (SPCE) test strips is described. SPCE test strips with and without glucose oxidase [i.e., GOD(+)-SPCEs and GOD(-)-SPCEs] were used and the chronoamperometric currents of test glucose solutions with various spiked uric acid concentrations and Hct% were measured. By establishing the interference relationships between glucose concentrations and uric acid concentrations as well as Hct% values and with appropriate corrections, the whole blood glucose determinations could be made to be more accurate and comparable to those determined by the reference YSI method. Specifically, the use of the Delta I value, i.e., the current difference between GOD(+)-SPCE and GOD(-)-SPCE measurements, would reduce most of the uric acid/biochemical interferences. An interpolation method was also established to correct for the glucose determinations with Hct% interferences. The Hct% corrections using the interpolation method are especially important and necessary for those blood samples with glucose concentrations higher than 110 mg dL(-1) and Hct% values lower than 35%. This approach should also be applicable to other biochemical determinations using similar electrochemical techniques.