GB/T 4372.1-2014 in English

《GB/T 4372.1-2014直接法氧化锌化学分析方法 第1部分：氧化锌量的测定 Na2EDTA滴定法》由TC243（全国有色金属标准化技术委员会）归口，TC243SC2（全国有色金属标准化技术委员会重金属分会）执行，主管部门为中国有色金属工业协会。

Methods for chemical analysis of zinc oxide produced by direct process -
Part 1: Determination of zinc oxide content - Na2EDTA titration method

1 Scope

This part of GB/T 4372 specifies the methods for determining the zinc oxide content of zinc oxide produced by direct process.

This part is applicable to the determination of zinc oxide content of zinc oxide produced by direct process, with the determination range ≥ 98.00%.

2 Method summary

Dissolve the specimen with dilute sulfuric acid, add potassium iodide into the hexamethylene tetramine-sulfuric acid buffer solution with a pH of 5~6 to mask the cadmium, add sodium sulfite to mask the lead and, taking xylenol orange as the indicator, titrate with Na2EDTA standard solution until the solution takes on bright yellow.

3 Reagents

Unless otherwise specified, only the recognized analytical reagents and distilled water or deionized water or water with equivalent purity shall be used during the analysis.

3.1 Ascorbic acid.

3.2 Reference zinc oxide (ωZnO≥99.999%): ignite at 800℃ for 2 h~3 h before use, take it out and cool it to ambient temperature in a desiccator.

3.3 Sulfuric acid (ρ 1.84 g/mL).

3.4 Ammonia.

3.5 Sulfuric acid (1+3).

3.6 Ammonia (1+1).

3.7 Hexamethylene tetramine-sulfuric acid buffer solution (pH of 5 to 6): weigh 300 g of hexamethylenetetramine in a 2,000mL beaker, add 950 mL of water to dissolve it (if the

Foreword i
1 Scope
2 Method summary
3 Reagents
4 Apparatus
5 Specimen
6 Analysis procedures
7 Calculation of analysis results
8 Precision
9 Test report