Final answer:
Alcohol is required along with bilirubin and diazo reagent in the Malloy & Evelyn Method for measuring total bilirubin to produce azobilirubin.
Step-by-step explanation:
When measuring total bilirubin using the Malloy & Evelyn Method, alcohol is needed along with the bilirubin and diazo to produce azobilirubin. This is because unconjugated bilirubin does not react with the Diazo reagent to give a color. However, when alcohol is added, it yields a purple-red color which indicates the presence of indirect bilirubin. This test is known as the indirect Van Den Bergh test and is useful for diagnosing conditions like hemolytic and infective jaundice.