Enzyme sensor for the determination of lactate and lactate dehydrogenase activity

Abstract

L-Lactate monooxygenase was immobilised by gelatin entrapment and fixed to a Clark-type oxygen probe. The resulting enzyme sensor was utilised in a Glukometer, an enzyme electrode based analyser. With this combination L-lactate was determined with a linear range between 10^–5 and 6 × 10^–4M. The relative standard deviation was below 1% and the stability of the sensor was 55 d. By addition of NADH and pyruvate to the measuring solution, sequential determination of lactate and lactate dehydrogenase activity was possible. The linear measuring range for the latter was 4.5 × 10^–8–9 × 10^–7 mol s^–1 l^–1(2.7–54.0 U l^–1). With human plasma and serum good agreement between the sensor and spectrophotometric methods was obtained.