Which accelerator is used in the Evelyn-Malloy method?

• A. 50% methanol
• B. caffeine
• C. Ascorbic acid
• D. Sodium acetate

Answer: (A)

In the Malloy-Evelyn bilirubin assay, bilirubin reacts with diazotized sulfanilic acid to form a colored complex, but bilirubin’s limited solubility in water can hinder full color development. Using an organic solvent like methanol boosts bilirubin solubility and facilitates the reaction, so a 50% methanol solution acts as the accelerator to produce a stronger, more reliable color signal. Caffeine is an accelerator in a different bilirubin method (enhancing color development there), while ascorbic acid and sodium acetate don’t serve this purpose in the Evelyn-Malloy procedure.