Question
You perform a biuret test, letting the samples stand for 10 minutes. How do you think...
You perform a biuret test, letting the samples stand for 10 minutes. How do you think the results may be affected?
A The results will not be affected. The reagent reacts instantly.
B Ten minutes is less than the required reaction time, so the color will not be as dark. This means that you will detect less analyte than is actually in the sample.
C Ten minutes is less than the required reaction time, so the color will not be as dark. This means that you will detect more analyte than is actually in the sample.
D Ten minutes is more than the required reaction time, so the color will be darker.
During the experiment, the solutions were allowed to stand for 20 minutes after the addition of Biuret reagent. Therefore, I do not see how "A" would be the correct option. Please explain your answer.
Answers
Biuret test is performed to detect the presence of peptide bond in a substance. It detects the presence of protein in a sample. Under biuret reagent the reaction is very quick almost takes place instantly as if autocatalyzed. In presence of peptide bond a copper (II) ion forms a violet coloured complex compound. So, even letting the sample stand for 10min will not affect the results. Therefore, correct option is (A)