[A colorimetric method for determination of delta-bilirubin in serum using bilirubin oxidase (Trachyderma tsunodae)]

We developed a colorimetric method to measure delta-Bilirubin in human serum using bilirubin oxidase from Trachyderma tsunodae and diazo reagent. In the first step, bilirubin fractions except for delta-Bilirubin, such as diconjugated, monoconjugated and unconjugated forms, are removed by enzymatic oxidation at pH 8.0 in the presence of sodium salicylate. In the second step, delta-Bilirubin remaining after enzymatic oxidation is determined by the conventional indirect diazo method. The results obtained by this method showed intra-day CV of 2.4%, satisfactory linearity and good correlation (r = 0.93, p less than 0.001) with those obtained by high performance liquid chromatography method. This simple and rapid method was clinical useful for determining the bilirubin fractions in sera of hepatic patients.