Why you add zinc dust in mulliken barker test?

Zinc dust is added in the Mulliken-Barker test to reduce any oxidized forms of the carbonyl compound present in the reaction mixture. This reduction facilitates the formation of the corresponding alcohol, which can then react with the reagent to form a colored complex. The presence of zinc dust helps improve the sensitivity and accuracy of the test by ensuring that the carbonyl compounds are fully converted to their reduced forms, allowing for better detection and quantification.