How To Test The Assay Of Sodium Metabisulfite

Reagents And Materials:

1. Iodine standard titration solution: Iodine standard titration solution

2. Ice acetic acid solution:1+3;

3. Sodium thiosulfate standard titration solution: c (Na2S203) approximately 0.1mol/L;

4. Soluble starch solution: 5g/L;

Analysis Steps:

1. Transfer 50ml of iodine standard titration solution to an iodine

volumetric flask. Dissolve about 0.2g sample, accurate to 0.0002g, added to the iodine solution, stoppered, frozen, put it in the dark place for 5 minutes.

Added to 5ml of glacial acetic acid solution, titration with sodium thiosulfate standard titration solution, when near the end, add 2ml soluble starch solution and continue titration until the solution blue color disappears as the end point.

2. At the same time take 50 ml iodine standard titration solution, blank test in the same conditions.

Results Calculation

Main content of sodium metabisulfite (Na2S2O5) the mass fraction of W1 and its value is expressed in%, according to equation (A.1):

Main content of sodium metabisulphite

Notice:

V0-Blank test of sodium thiosulfate standard titration solution consumed volume, the unit is ml (ml);

V1-Titration test solution of sodium thiosulfate standard titration solution consumed volume, the unit is ml (ml);

c-The concentration of sodium thiosulfate standard titration solution accurate numerical, unit for moles per liter (mol/L);

m-The Numerical of the sample quality, the unit is gram (g);

M-A quarter sodium metabisulfite (1/4 Na2S2O5) numerical of molar mass, units of grams per mole (g/mol) (M = 47.52).

Take the arithmetic mean of the parallel determination results of the measurement results, the absolute difference between the two parallel determination results is not more than 0.2%.