Final answer:
The second step in the Jendrassik-Grof method for total bilirubin analysis reacts azobilirubin with Nitric Acid in order to get azobilirubin measured at 600 nm.
Step-by-step explanation:
The second step in the Jendrassik-Grof method for total bilirubin analysis reacts azobilirubin with Nitric Acid in order to get azobilirubin measured at 600 nm. This step is known as the Van Den Bergh test. The reaction between azobilirubin and nitric acid produces a purple-red color that can be measured spectrophotometrically at 600 nm.