Centrifugal analyzer method for total bilirubin in serum by use of diazotized 2-chloroaniline-5-sulfonic acid

We describe two centrifugal analyzer methods for mea-suring total bilirubin in serum. Diazotized 2-chloroani-line-5-sulfonic acid is used in both. In the first procedure, ethylene glycol and methanol are used as an accelerator solvent; results correlate well with those by a Jendrassik and Grof method adapted to the centrifugal analyzer, but there is considerable hemolysis interference. In the second method, dimethyl sulfoxide is used with the ethylene gly-col/methanol solvent and almost all hemolysis interference is eliminated. For either method, a 15-L sample is re-quired. In the second method, instrument response is lin-early related to concentration to 250 mg/L and the within-run precision (CV) is about 1 %. One problem in measuring bilirubin, aside from its being a light-sensitive substance (1), is interference from hemolysis