NEET BIOLOGY

Detailed explanation-1: -Therefore, the biuret test can also be used to gauge the amount of protein present in the analyte. In this test, the presence of peptides results in the formation of pale purple coloured (or mauve coloured) coordination compounds of the copper(II) ion (when the solution is sufficiently alkaline).

Detailed explanation-2: -In the presence of alkaline, when Biuret is reacted with dilute copper sulphate, a purple coloured substance is formed. The reason behind this colour is the formation of a chelate complex or the copper coordination complex.

Detailed explanation-3: -A positive test is indicated by: a deep blue/purple color due to the copper ion complex with the amide group of the protein.

Detailed explanation-4: -We used Biuret’s reagent to detect the presence of proteins in solution. The reagent is pale blue when pure, but when mixed with proteins, the resulting reaction produces a pale purple color.

Detailed explanation-5: -Water plus Biuret’s reagent is a negative control for the protein test. It demonstrates a negative test result (no protein present). Egg albumin plus Biuret’s reagent is a positive control for the protein test. It demonstrates a positive test result (protein is present).