Clinical evaluation of amperometric enzyme electrodes in continuous-flow analysis for glucose in undiluted whole blood

Abstract

We have evaluated the carbon-paste enzyme/wall-jet electrode in continuous-flow analysis for glucose in undiluted whole blood. Responses of the electrode to protein-based and aqueous samples under wall-jet configuration are described. Imprecision in the flow-injection mode was <2% for glucose values in the usual analytical range (1-25 mmol/L). The dynamic range for glucose was from 0.03 to 45 mmol/L, with about 100% recovery of added substrate. The performance of the electrode (y) in flow-injection and steady-state modes was compared with a colorimetric method (x; Kodak Ektachem XR700), yielding linear-regression equations of y = 1.152x + 0.295 and y = 0.979x + 0.500, respectively. Among the anticoagulants, blood preservatives, and interfering substances investigated, only ascorbic acid gave a significant positive bias. The electrode exhibited good stability for analyses of undiluted whole-blood samples.