Final answer:
In the total bilirubin assay, bilirubin reacts with diazotized sulfuric acid to form azobilirubin which is part of the Van Den Bergh reaction used to diagnose liver conditions.
Step-by-step explanation:
In the total bilirubin assay, bilirubin reacts with diazotized sulfuric acid to form azobilirubin. This reaction is part of the diagnostic tests used to understand bilirubin metabolism in the body and determine the presence of certain liver conditions, like obstructive jaundice. This diagnostic approach underlines the Van Den Bergh reaction, which helps differentiate between conjugated and unconjugated bilirubin in the body. Conjugated bilirubin reacts directly to form a purple red color, known as the direct Van Den Bergh reaction. Conversely, unconjugated bilirubin requires the presence of alcohol to show the purple red color, known as the indirect Van Den Bergh reaction.