Lactic acid dehydrogenase, stability

Gorton et al. reported carbon paste electrodes based on Toluidine Blue O (TBO)-methacrylate co-polymers or ethylenediamine polymer derivative and NAD" " with yeast alcohol dehydrogenase for the analysis of ethanol [152,153] and with D-lactate dehydrogenase for the analysis of D-lactic acid [154]. Use of electrodes prepared with dye-modified polymeric electron transfer systems and NAD+/NADH to detect vitamin K and pyruvic acid has also been reported by Okamoto et al. [153]. Although these sensors showed acceptable performances, insensitivity to ambient oxygen concentration, sensor stability and lifetime still need to be improved to obtain optimal dehydrogenase based enzyme biosensors. 

Most investigations have employed the technique of Barker and Sum-merson (Bl) (transformation into acetaldehyde, which is estimated colorimetrically by its reaction with p-hydroxydiphenyl) or a modification of the original technique (B20, H30, M6, T25). More recent studies have been made with specific enzymatic methods using lactic dehydrogenase (H27). The stabilization of lactic acid in blood samples has been studied by Long (L16). 

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