[Share] GB/T 3049-2006 Determination method of total iron in ethylene glycol

Determination of total iron in ethylene glycol GB/T 3049-2006

1. Determination principle

● Reduce the Fe3 + in the sample to Fe2 + with ascorbic acid. At pH = 2.5~ 9, Fe2 + can form an orange-red complex with o-phenanthroline. At maximum absorption

At a wavelength of 510m, the absorbance was measured with a spectrophotometer.

2. Determine the required reagents

2.1 Hydrochloric acid, 180 g/L solution, 409 ml of hydrochloric acid solution with a mass fraction of 38% (γ = 1.19 g/mL) is diluted to 1000 mL with water and mixed well (be careful during operation).

2.2 Ammonia solution, 85g/L solution, 374 ml of 25% ammonia solution (γ = 0.910 g/mL) was diluted to 1000 mL with water and mixed.

2.3 Acetic acid-sodium acetate buffer solution, pH = 4.5 at 20 ° C, weigh 164 g of anhydrous sodium acetate and dissolve in 500 ml of water, add 240 ml of glacial acetic acid, and dilute to 1000 mL with water.

2.4 Ascorbic acid, 100g/L solution, this solution cannot be used after one week.

2.5 1g/L solution of 1,10-phenanthroline hydrochloride-hydrate (C12H8N2.HCl. H2O), or 1,10-phenanthroline-hydrate (C12H8N2.H2O), dissolve 1g with water

 1,10-Phenanthroline Hydrate or 110-Phenanthroline Hydrochloride-Hydrate and diluted to 1000 mL. Store in the dark with a colorless solution.

3. Analysis steps

3.1 Accurately weigh 60g of ethylene glycol sample;

3.2 Adjust the pH to 2 with hydrochloric acid solution (check with precision pH test paper);

3.3 Add 1ml ascorbic acid solution;

3.4 Then add 20 ml of buffer solution and 10 ml of 1,10-phenanthroline solution.

3.5 Dilute with water to the scale, shake well, and leave for not less than 15 minutes.

3.6 Colorimetric at a wavelength of 510nm.

4. Calculation formula

4.1 The iron content in the test solution and the test blank solution is found from the standard curve by the corresponding absorbance value measured after color development, and the international standards related to the product will give the appropriate

The formula for calculating the final result.

Where: Fe (%) = m/M

M - Displays the value of the mass in grams (ug);

The mass of the ethylene glycol sample is weighed in grams (g).