When used for reducing sugar (glucose, fructose, maltose), the phenomenon is light blue → brick red, but it needs water bath heating. The main reason is the newly produced copper oxide suspension.

2: Bancroft reagent

It is mainly used to detect urine sugar and diabetes.

3. Sudan Ⅲ dye solution to identify fat → orange.

4: biuret reagent

Used to recognize protein (most enzymes, hormones, antibodies).

(So: If there is an enzyme in the solution, it will turn purple. ) The phenomenon is blue → purple.

5: Iodine solution

Used to identify the phenomenon that starch (non-reducing sugar) turns blue.

6: gentian violet

The phenomenon used to identify chromosomes is → purple.

Now the formulas of the two favorite reagents in the college entrance examination are listed as follows.

1, linfei reagent:

Composition: 0. 1g/ml NaOH (solution a) and 0.05g/ml CuSO4 (solution b).

Usage: Drop 4~5 drops of solution B into 2ml of solution A to obtain Cu(OH)2 suspension, namely phenanthrene reagent, and then pour it into the solution to be tested and heat it in water bath or directly.

If there is reducing sugar in the solution to be tested, it is brick red.

2, biuret reagent:

Components: 0. 1g/ml NaOH (solution a) and 0.0 1g/ml CuSO4 (solution b).

Usage: Add 2ml of solution A to the solution to be tested, shake well, then add 3~4 drops of solution B, and shake well.

If there is protein in the test, it will appear purple.

Respondent: A classmate of Class 08 bioengineering in School of Environmental Engineering, Chang 'an University.