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positive result for when buiret is added to protein is blue or violet/pale lilac colour. (not pink).
positive result for when iodine is added to starch is blue or black colour (not pink).
Wiki User
∙ 13y ago
Wiki User
∙ 12y agoThe biuret test is a chemical test used for detecting the presence of peptide bonds. In a positive test, a copper(II) ion is reduced to copper(I), which forms a complex with the nitrogens of the peptide bonds in an alkaline solution. A violet color indicates the presence of proteins.
Copy and pasted straight from wikipedia. Did you do any research at all before asking this? do your own homework.
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just sayin, wikipedia is unreliable, but yea in this case its right. the solution will turn pink/violet.
Wiki User
∙ 11y agoThe Biuret reagent is made of potassium hydroxide (KOH) and hydrated copper(II) sulfate, together with potassium sodium tartrate and has blue colour.
The reagent turns from blue to violet in the presence of proteins, blue to pink when combined with short-chain polypeptides.
Wiki User
∙ 13y agoIt will change violetish because the solution reacts with the peptide bonds that link the individual amino acids into the protein chains.
Wiki User
∙ 12y agoA Biuret test gives positive when it turns violet or pink.
Wiki User
∙ 11y agoWhen tested with iodine, you will see a blue-black colour if starch is present.
If there is no starch present, the iodine will remain brown.
Wiki User
∙ 10y agoIn the Biuret test, the blue reagent turns violet it it detects proteins, and changes to pink when combined with short-chain polypeptides.
Wiki User
∙ 14y agodeep blue/purple color
Wiki User
∙ 12y agoProteins
Gisella Gomez
purple
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Does phenol give a positive biuret test?
No. The Biuret test only gives a positive result if a peptide bond exists. Phenol doesn't have a peptide bond, so it will not give a positive test.
If Biuret and Millon's test give positive result what is the conclusion?
The conclusion is that the sample contain proteins.
Would glucose give a positive result with the Biuret test?
No because glucose does not consist of two or more peptide bonds
Would cysteine test positive in a biuret test?
no! no change in colour confirms presence of cysteine
Would albumin give a positive biuret test?
Hey. okay.. the biuret test is a test for peptide bonds. when CuSO4 is added to KOH, an alkaline solution, nitrogen atoms from the peptide bond forms a purple compound with the Cu2+ ions. hope this helps! read it in a text book.
How many of these chemical groupings must be present in a molecule to give a positive biuret test?
you should have at least 2 of these,to obtain a positive result in Biuret's test. because biuret test is a test used to detect if there is peptide linkages.
Does phenol give a positive biuret test?
No. The Biuret test only gives a positive result if a peptide bond exists. Phenol doesn't have a peptide bond, so it will not give a positive test.
What is the color of biruet solution?
The biuret solution used in the biuret test for peptide bonds is blue in the absence of peptide bonds or biuret which also results in a positive result. A positive result for peptide bonds or biuret is apparent as the biuret solution turns purple/violet in color.
Is biuret test suitable to test the presence of proteins in the urine?
Yes, the biuret test will indicate the presence of peptides. If it turns violet, it is a positive result.
If Biuret and Millon's test give positive result what is the conclusion?
The conclusion is that the sample contain proteins.
Does pepsin test positive in biuret test?
No
How do you tell if a substance contains protein by using biuret test?
If Biuret Reagent is related to the presence of Protein macromolecules, then a positive result will change it's colour from blue to violet.
Would glucose give a positive result with the Biuret test?
No because glucose does not consist of two or more peptide bonds
Will glutamic acid give a positive biuret test?
Amino acids doesn't react with the biuret reagent.
What color is a positive test for protein?
A positive test, when using Biuret reagent, would be purple-ish
What are the biuret test results for egg albumin?
Yes. The Biuret test is a test for the presence of peptide bonds. Since albumin is a class of protein, and proteins are composed of many amino acids joined together by peptide bonds, the test will yield a positive result.
Would cysteine test positive in a biuret test?
no! no change in colour confirms presence of cysteine
