8.1. Defining the properties of vitamin b2, b3, b6,

Equipment, tools and materials: glasses, chemical, pypetky, solutions or dry preparations of vitamins B2, B3, B6, tubes, tripods, UV transparent glasses or tubes, electric, safe source of UV light, pH meter, indicator paper, refractometer, water, alcohol alcohol, cotton, filter paper, 0.1 M KOH solution, 5% solution of acetate of copper. 10% acetic acid, 5% solution of ferric chloride (III).

The order of performance

Prepare the working solution of vitamin B2. With a dry preparation to cook 10 - 20 ml 0.01% solution.

Using indicator paper or a pH meter to determine the pH of solutions. Along with a pH meter determined using refractometer refractive index of the solutions. The results of measurements and color of the preset table

On the source of ultraviolet radiation.

Using transparent to UV light dishes to assess the ability of samples for fluorescence, the data recorded in the table.

Add to a solution that fluorestsuye few drops of 0.1 M KOH solution, to monitor the disappearance of fluorescence. Measure the pH again and the index of refraction.

Treatment of experimental data

Table 8.1

	Свіжий розчин	Після зміни рН
Колір
рН
Покажчик заломлення
Наявність флуоресценції
Наявність осаду

8.2. The color reaction of vitamin b6 chloride of iron (III)

Mix 2 ml of 5% solution of ferric chloride (III) and 2 ml of 5% solution of vitamin B6. The result should be a change in the color red.

8.3. The color reaction of vitamin b3 with copper acetate

Add 100 mg of vitamin E in a test tube with 2 ml of 10% acetic acid, after dilution mixture add 2 ml of 5% solution of copper acetate. Must be formed precipitate blue.

pre flask stopper. Then the content is titrated with a solution of 2,6-dyhlofenolindofenolyatu sodium.

8.4. Determination of vitamin c

Procedures and recommendations for performance

Extraction. To prepare the sample extract samples weighing from 5 to 50 g weighed with pohybkoyuyu ± 0,01 g

For extraction of vitamin C with dry food samples 5-10 g sample is ground in a mortar with a small amount of the mixture or solution ekstrahuvalnoho acids (at least 1 cm3 of solution per 1 g of sample) and sand transferred to a volumetric flask or graduated cylinder capacity of 100 cm3, washing the mortar and small portions pestyk ekstrahuvalnoho solution until the volume reaches the mark. Stand for 10 minutes, stirred and filtered.

For extraction of vitamin C from foods thick consistency sample of 5-10 g homogenized sample of no more than 2 minutes with a little ekstrahuvalnoho solution (at least 1 cm3 of solution per 1 g of sample) and transferred to a volumetric flask or cylinder capacity of 100 cm3, washing the homogenizer small portions ekstrahvalnoho solution until the volume reaches the mark. Contents to stand for 10 minutes, stirred and filtered.

Visual titration. In the flask 50 or 100 cm3 pipette made ​​from 1 to 10 cm3 extract, dilute with water to 10 cm3 and titrated with a solution of sodium 2,6-dyhlorfenolindofenolyatu to light pink color that persists for 15-20 sec.

At the same time control experiment is carried out on the contents of the product substances reduces. To this flask is placed in a same volume of extract, as well as to determine (1 to 10 cm3) was added an equal volume of acetate it buffer formaldehyde solution in a volume equal to half the volume of buffer solution, stirred and allowed to stand for 10 minutes, closing.

Processing of obtained data

Ascorbic acid mass fraction X,%, calculated by the formula

where V1 - volume of solution of sodium 2,6-dyhlorfenolindofenolyata spent for titration of the extract sample, cm3; V2 - volume of solution of sodium 2,6-dyhlorfenolindofenolyata spent a control experiment, cm3; T - titer solution of 2,6-dyhlorfenolindofenolyata sodium g/cm3; V3 - the volume of the extract obtained by extraction of vitamin C with sample product cm3; V4 - extract volume used for titration cm3; m-mass of sample products, g

Analysis of the results

The student should draw conclusions about the stability of vitamins. a comparative analysis of the properties of vitamins.

  Question for self-testing

1. What vitamins that they have molecular weight, chemical composition?

2. Which properties of vitamins used in the analysis and identification.

3. Which there are limits to the storage and research vitamins?

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