Jendrassik-Grof method

1. (for conjugated bilirubin) a fasting sample of serum or plasma is collected and acidified by the addition of hydrochloric acid. Ehrlich's diazo reagent is added so that the conjugated bilirubin begins forming blue azobilirubin. After 10 minutes the reaction is stopped and the amount of azobilirubin in the sample is measured. 2. (for total bilirubin) to an acidified fasting sample as in the previous method, caffeine benzoate is added as an accelerator for the unconjugated bilirubin to form azobilirubin. When the reaction is stopped, the azobilirubin in the sample thus represents the total of both conjugated and unconjugated bilirubin.