Abstract
We present an automated enzymatic method for simple, rapid and sensitive assay of various biological substances in serum by use of H2O2 electrode. A flow through chamber was specially designed to connect the H2O2 electrode with Technicon Auto Analyzer and to allow the reaction mixture to pass through the surface of the electrode. H ydrogenp eroxidee nzymaticallyp roduced was determined amperometrically.
1) Optimalc onditionsf or measurementso f uric acid, c holesterolt, riglycerides and phospholipids were established. Good results were obtained in a precision study. Turbid or coloured serum specimens did not affect the electrode response. Interference by catalase was avoided by the additiono f NaN3. A scorbateo xidasep rotected the interferenceb y ascorbica cid.
2) The type of buffer solution and pH value had an effect on the electrode response. Each buffer solution had an original basal electric current and showed different response to H2O2 added. Phosphatea nd PIPESw ere shown to be more favorablef or the H2O2 electrodet han Tris-HCl and other Good's buffers.
3) Effect of various compounds present in reaction mixture or specimens on the electrode response was investigated. Reducing compounds such as ascorbic acid, uric acid, cysteine or glutathione which consume dissolved oxygen was found to increase the electrode response even in the absence of H2O2. Pyruvic acid and a-ketoglutaric acid continuously decreased the current level by consuming H2O2.
