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.

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.

Дата добавления: 2015-11-14