How to use the biuret reagent, what are the solutions A and B of the biuret reagents

Biuret reagent.

A is the quality score.

for the aqueous solution of NaOH;

Biuret reagent B is a mass fraction of.

g ml CuSO4 in water.

First, add biuret reagent A to the solution to be tested

3ml, shake evenly (to create an alkaline environment), and then add 1 2 drops of biuret reagent B, shake evenly. If the solution to be tested contains protein, you will see the solution turn purple. Has two or more peptide bonds.

can produce a purple reaction with biuret reagent.

The peptide bond of the protein can be complexed with Cu2+ in an alkaline solution to form a purple complex.

The shade of color is directly proportional to the protein concentration.

Extended Materials. To determine whether a protein is present in a biological tissue, a biuret reagent is used, and a biuret reaction occurs.

The diuret reaction is essentially a purple reaction between Cu2+ and the biuret reagent in an alkaline environment.

The protein molecule contains many peptide bonds similar to the structure of H2NOC-NH-conhH2, so the protein can react with the biuret reagent in purple, and the presence of the protein can be identified with the biuret reagent.

Biuret reagent.

First, the mass fraction of biuret reagent a (sodium hydroxide is.

g ml of aqueous solution) was added to the tissue sample solution, shaken evenly (an alkaline environment must be created), and then biuret reagent b (the mass fraction of copper sulfate was.

g ml of aqueous solution), shake well. If the tissue contains protein, you will see the solution turn purple. Compounds with two or more peptide bonds can react purple with biuret reagents.

The peptide bond of the protein can be complexed with Cu2+ in alkaline solution to form purplish-red compounds. The shade of color is directly proportional to the protein concentration.

1. The composition of biuret reagent a is sodium hydroxide.

g ml of aqueous solution; The composition of biuret reagent B is copper sulfate with a mass fraction of .

g ml of aqueous solution; 2. The first reason is that after adding liquid A, there is no sufficient oscillation, which causes the reaction of sodium hydroxide and copper sulfate at the mouth of the test tube to form copper hydroxide precipitation; The second is to add too much B solution, copper sulfate masks the purple color, as long as 4-5 drops.

The biuret reagent is composed of liquid A (sodium hydroxide solution by mass) and liquid B (copper sulfate solution by mass).

For the identification of proteins, it is necessary to add solution A before adding solution B, and the amount of solution B added should be small.

The substance is different, and the diuret reagent A solution is an aqueous solution of NaOH. Diuret B solution is an aqueous solution of CuSO4.

The difference between the two: the mass fraction of solution A of diuret reagent is g ml at different concentrations. The mass fraction of solution B of biuret reagent was g ml.

In order to create an alkaline environment, the amount of diuret reagent A is generally 3 ml. The purpose of diuret reagent B solution is to make the peptide bond of the protein complex with Cu2+ complex in alkaline solution. The shade of color is directly proportional to the protein concentration.

Add a smaller amount, just a few drops.

Note: When using biuret reagent, add g ml of sodium hydroxide solution first, and then add g ml of copper sulfate in aqueous solution. If copper sulfate solution is added first, and then sodium hydroxide NaOH solution is added, the alkaline environment cannot be fully created.

Diuret is a chemical substance, and the two reagents used to detect proteins are called biuret reagents because the detection principle is similar to the formation of biuret.

The above content refers to: Encyclopedia-biuret reagent.

The composition of the biuret reagent is sodium hydroxide at a mass concentration.

solution and copper sulphate solution at a mass concentration.

The biuret reagent is an analytical chemistry reagent used to identify proteins. It is an alkaline copper-containing test solution that is blue in color and consists of sodium hydroxide or potassium hydroxide.

Copper sulphate and potassium sodium tartrate are formulated.

The biuret reagent is originally used to detect biuret because the protein molecule contains many peptide bonds that are structurally similar to biuret.

Therefore, it can also react with copper ions in alkaline solution. When the substrate contains peptide bonds, the copper in the test solution coordinates with the polypeptide, a complex.

Purple in color. Concentrations can be analyzed colorimetrically, with a wavelength of 540 nm in the UV-Vis spectrum. The sensitivity of the identification reaction is 5-160 mg ml.

Copper sulfate is used in the diuret reagent, while potassium hydroxide is only used to provide an alkaline environment, so it can be replaced by other bases such as sodium hydroxide. Adding potassium iodide to the reagent will prolong the life of the reagent. The function of potassium sodium tartrate is to protect the complex ions generated by the reaction from being precipitated into respectful stuffy precipitate, so that the reagent becomes ineffective.

1. The role is different

Filin reagent. is a newly formulated solution that reacts with the aldehyde group under heating conditions and is reduced to a brick-red precipitate that can be used to identify soluble reducing sugars.

exists. When the soluble reducing sugar is identified with Filin reagent, the color change process of the solution is: light blue, brown, brick red (precipitate).

When identifying whether a protein is present in a biological tissue, the biuret method is commonly used, using a biuret reagent, and a biuret reaction occurs. The diuret reaction is essentially a purple reaction with the biuret reagent in an alkaline environment. Protein molecules, on the other hand, contain many peptide bonds that are structurally similar to biuret.

Therefore, the protein can react with the color of the biuret reagent.

2. The configuration method is different

Preparation method of Filin reagent: G mi NaOH (solution A) and G mi CuSO4 (solution B). The solution is prepared by mixing 50 g of sodium hydroxide.

and 137 g potassium sodium tartrate in 500 mi distilled water (store in a bottle with a rubber stopper). Liquid B is prepared by combining g crystallized copper sulfate.

Dissolve in 500 ml of water and add MI sulfuric acid. Mix well.

Biuret reagent A is the mass fraction.

g ml of aqueous NaOH solution; Biuret reagent B is a cuSO4 solution in water with a mass fraction of g ml. First, add 3ml of biuret reagent A to the solution to be tested with uniform shaking (to create an alkaline environment), and then add 1 2 drops of biuret reagent B with uniform shaking.

3. Different ways to use:

When using the Filin reagent, the solution is mixed with the solution (drops of the solution are dropped into the solution) and then used immediately.

When using the biuret reagent, first add the solution (2ml), shake and shake well to create an alkaline reaction environment, and then add 3 4 drops of the solution to the hood, shake and observe the phenomenon.

Because if liquid A and liquid B are added together at the same time, there will be reactions between them, which will affect the effect of the experiment, so it is better to add them separately.

Liquid A is added first to provide an alkaline environment, and the protein contains aldehyde groups, together with freshly made copper hydroxide.

A redox reaction occurs.

The resulting copper peroxide can only exist in an alkaline environment, and because the copper peroxide is brick-red precipitate, it will appear purple when combined with blue copper ions.