Reaction of unconjugated and conjugated bilirubin with Fast Red TR and related diazonium salts
Hoffmann, G.E.; Hiefinger, R.; Weiss, L.
Journal of Clinical Chemistry and Clinical Biochemistry 23(11): 759-763
1985
ISSN/ISBN: 0340-076X PMID: 4086980 Document Number: 257721
In the present study, the reaction of 15 different diazonium salts with serum bilirubin is examined. It is shown that the selectivity of the determination of non-conjugated and total bilirubin greatly depends on two conditions: the pH-value of the reaction mixture and the nature and position of substituents within the benzene ring. Introduction of "electron-pushing" groups such as the o-methyl group of Fast Red TR will change the reactivity of the diazonium cation towards bilirubin in such a way that the co-reaction of the conjugated fraction becomes negligible at pH-values between 2 and 5. After neutralization to pH 7 the total bilirubin can be determined.