| Abstract: | A method has been developed for the modification of a carbon fiber microcylinder electrode with acylation. The stability and surface coverage of the Toluidine Blue O-modified microelectrode were studied by cyclic voltammetry. The modified electrode showed significant activity for the electrocatalytic oxidation of NADH in pH 6.8-7.8 solution. The catalytic current increased linearly with increasing concentration of NADH from 4.0 x 10(-5) to 1.5 x 10(-3) M. A simple amperometric determination based on electrochemical detection of NADH produced from the enzymatic reaction of lactate with NAD(+) under the catalysic effect of lactate dehydrogenase (LDH) is reported. The experimental factors which had primary influence on the analytical performance were studied. The sensor had a linear response over a range of LDH concentrations from 5.0 U l(-1) to 200 U l(-1) at -0.2 V vs. SCE under optimum conditions. A satisfactory result was obtained for the determination of LDH in clinical blood samples. |
