Abstract
We developed a new automated method for determining serum total and direct bilirubin using nitrite as a unique oxidizing agent. Bilirubin is quickly oxidized by nitrite in a pH3.7 buffer solution with a decrease in the absorbance at 450nm. We used n-tetradecyltrimethyl ammonium bromide as the reaction accelerator for total bilirubin measurement, and polyoxyethylene (n-alkyl or iso-alkyl) ether and polyvinylpyrrolidone as the inhibitor of oxidation with free bilirubin for direct bilirubin measurement. Our new method showed good reproducibility, no interference from coexisting substances in serum, good correlation with various commercial kits such as enzymatic and chemical methods, and reasonable cost. These results indicated the usefulness of our new method.
