GB/T 4702.5-2008Chromium metal - Determination of aluminium content - EDTA titrimetric method and flame atomic absorption spectrometric method (English PDF)

3.1 Principle

Sample was dissolved with hydrochloric acid, perchloric acid smoke, then made basic with ammonia to separate most of the chromium. Hydroxide precipitate dissolved in nitric acid,

Join smoke perchlorate, chromium chloride acid generated volatile chromium residue with hydrochloric acid, water and dissolved salts, after adjusting the pH to sulfosalicylic acid to indicate

Agents, disodium edetate After titration standard solution titration iron, plus disodium edetate over standard titration solution, pH5.3 ~ pH5.9 acidic medium to xylenol orange as indicator. Zinc standard titration solution titrate excess of disodium edetate. plus

The ammonium fluoride complex aluminum and release a considerable amount of disodium edetate, and then the zinc standard solution titration titration. According to its consumption, calculated

The percentage content of aluminum.

3.2 Reagents and materials

Unless otherwise indicated in the analysis using only recognized as analytical grade reagents and distilled water or its equivalent purity water.

3.2.1

ammonium chloride as a solid.

3.2.2

ammonia, rho0.90g/mL.

3.2.3

perchloric acid, rho1.67g/mL.

3.2.4

hydrochloric acid, rho1.19g/mL.

3.2.5

nitrate, rho1.42g/mL.

3.2.6

hydrochloric acid, 1 + 1.

3.2.7

hydrochloric acid, 99 + 1.

3.2.8

hexamethylenetetramine solution, 250g/L.

3.2.9

hexamethylenetetramine solution, 5g/L.

3.2.10

sulfosalicylic acid solution, 5g/L.

3.2.11 XO solution, 1g/L

Alcohol formulation, now with the current.