Final answer:
The most common quantitative methods for urobilinogen involve its reaction with Diazo reagent to form a red color.
Step-by-step explanation:
The most common quantitative methods for urobilinogen involve its reaction with Diazo reagent to form a red color. There are two types of tests commonly used: the Direct Van Den Bergh test and the Indirect Van Den Bergh test. In the Direct Van Den Bergh test, conjugated bilirubin reacts with Diazo reagent to produce a purple red color, while in the Indirect Van Den Bergh test, unconjugated bilirubin reacts with Diazo reagent in the presence of alcohol to produce a purple red color.