A rapid and specific method for the estimation of glucose using and oxygen electrode and simple differentiating...

A simple differentiating circuit is described which, together with an oxygen electrode assembly, provides a rapid (20 sec) and cheap system for the estimation of glucose in body fluids using a sample volume of 20 microliter. Response was linear over the range 0-22 mmol/l. The complete system has been evaluated using plasma and whole blood. "Within-day" precision on control plasmas over the concentration range 2.73-8.33 mmol/l lies between 2.0 and 3.3% (C.V., n = 23); "day-to-day" precision was 4.6% (C.V., n = 23). On whole blood, to which nitrate had been added, precision was 4.5% (C.V., n = 15); precision using standard glucose solutions was never greater than 3.3% (C.V., n = 15) over the concentration range 1.1-22.2 mmol/l. Recoveries of added glucose to plasma and whole blood were greater than 90%. Good correlation between glucose values obtained by the oxygen electrode system described here and an automated system were obtained for plasma (r = 0.9902, n = 35) and whole blood (r = 0.9610, n = 35), although whole blood gave values on average 27% lower than plasma. The use of the system for the measurement of plasma cholesterol is also demonstrated.