GB/T 4324.1-2012Methods for chemical analysis of tungsten - Part 1: Determination of lead content - Flame atomic absorption spectrometry (English PDF)

1 Scope

This part of GB/T 4324 specifies tungsten powder, tungsten, tungsten carbide, tungsten trioxide, tungstic acid, blue tungsten, tungsten, ammonium paratungstate, ammonium metatungstate

Determination of lead content in the method.

This part is applicable to the determination of lead content in tungsten powder, tungsten, tungsten carbide, tungsten trioxide, tungstic acid, blue tungsten, purple tungsten, ammonium paratungstate and ammonium metatungstate set. The measurement range is 0.0003% ~ 0.0050%.

2 method summary

Tungsten powder, tungsten, fine, medium tungsten carbide decomposition with hydrogen peroxide; blue tungsten with hydrogen peroxide and sodium hydroxide decomposition; tungsten trioxide, tungstic acid,

Ammonium tungstate, ammonium metatungstate with sodium hydroxide decomposition; purple tungsten, coarse particles of tungsten carbide oxidation of tungsten trioxide after decomposition with sodium hydroxide. In alkaline

The solution was enriched with iron (III) as a coprecipitant, the residual tungsten was complexed with citric acid, and the amount of lead was measured on an atomic absorption spectrometer.

3 reagent

Unless otherwise stated, the reagents used in this section are analytical reagents that conform to national standards or industry standards, and the water used is distilled water.

4 instruments

Atomic Absorption Spectrometer with Lead Hollow Cathode Lamp.

In the best working conditions of the instrument, who can achieve the following indicators can be used.

--- Characteristic concentration. In the solution consistent with the substrate of the measurement solution, the characteristic mass concentration of lead is not more than 0.3µg/mL;

Precision. the maximum concentration of the standard solution measured 10 times the absorbance, the standard deviation should not exceed 1.0% of the average absorbance;

The standard deviation should not exceed the maximum of 10 absorbance measured with the lowest concentration of the standard solution (not the "zero concentration" standard solution)

Concentration Standard solution 0.5% of the average absorbance;

--- Working curve linearity. the working curve according to the concentration is divided into five segments, the highest section of the difference between the absorbance difference and the lowest of the difference in absorbance

Ratio, should not be less than 0.7.