1.2 - Feasibility of a L-(+)-Lactate Disposable Dry Chemistry Sensor

Abstract

This chapter elaborates the feasibility of l-(+)-lactate disposable dry chemistry sensor. The reduction of pyruvate to l-lactate is catalyzed by NAD-linked lactate dehydrogenase (LDH) in muscle to regenerate oxidized NAD, so that glycolysis can proceed in active skeletal muscle. Alternatively, l-lactate can be oxidized to pyruvate by at least two different types of l-lactate oxidases, utilizing oxygen as the electron acceptor. In the experiments, O2 was effectively replaced with 0.6 M potassium ferricyanide as the electron acceptor in an attempt to adapt an l-lactate assay to a dry chemistry sensor application. Feasibility of ferricyanide as an electron acceptor as well as a reaction endpoint determination was first characterized by hydrodynamic amperometry (HDA) utilizing a 3 mm platinum rotating disc electrode (RDE) and a Ag/AgCl reference electrode. The linear range exhibited with this system was well beyond the upper limit of normal for lactate in male serum at 1.77 mM/L. It is expected that the linearity could be extended to as high as 25 mM/L or more, levels evidenced in severe cases of lactic acidosis.