EVALUATION OF A MINIATURIZED THERMAL BIOSENSOR FOR THE DETERMINATION OF GLUCOSE IN WHOLE-BLOOD

A miniaturized thermal biosensor has been evaluated as part of a flow- injection analysis system for the determination of glucose in whole bl ood. Glucose was determined by measuring the heat evolved when samples containing glucose passed through a small column with immobilized glu cose oxidase and catalase. Samples of whole blood (1 mu l) can be meas ured directly, without any pretreatment. The correlation in the respon se between the thermal biosensor, the Reflolux S meter (Boehringer Man nheim), the Granutest 100 glucose test kit (Merck Diagnostica) and the Ektachem (Kodak) instrument was evaluated. The influence of the hemat ocrit value and of possible interferences is reported. The correlation measurements show that the thermal biosensor calibrated with aqueous glucose standards generally gives lower values on blood glucose than t he reference methods calibrated for serum or blood measurements. Mean negative biases range from 0.53 to 1.16 mmol/l. Differences in sample treatment clearly complicate comparisons and the proper choice of refe rence method. There was no influence from substances such as ascorbic acid (0.11 mmol/l), uric acid (0.48 mmol/l), urea (4.3 mmol/l) and ace taminophen (0.17 mmol/l) on the response to 5 mmol/l glucose. The hema tocrit value does not influence the glucose determination, for hematoc rit values of between 13 and 53%. (C) 1997 Elsevier Science B.V.