YS/T 37.1-2018Methods for chemical analysis of high pure germanium dioxide -- Determination of chlorine content by silver nitrate turbidimetric method (English PDF)

1 Scope

This Part specifies the determination of the chlorine content in high-purity germanium dioxide.

This Part applies to the determination of the chlorine content in high-purity germanium dioxide, with a determination range of 0.0050% to 0.1000%.

2 Method Summary

The test material was dissolved in sodium hydroxide and neutralized to a weakly acidic state with nitric acid. In dilute nitric acid medium, chloride ions reacted with silver ions to form silver chloride colloid. The silver chloride colloid remained suspended in the solution in the presence of the stabilizer glycerol. Turbidity was measured at 430 nm using a spectrophotometer to indirectly determine the chloride content.

3 Reagents and Materials

3.1 The water used in this Part is deionized water with a resistivity of no less than 18 Mohm·cm.

3.2 Nitric acid (rho = 1.42 g/mL), guarantee reagent.

3.3 Glycerol, analytical reagent.

3.4 Nitric acid (1+1), prepared from nitric acid (3.2).

3.5 Glycerol (1+1), prepared from glycerol 3.3.

3.6 Silver nitrate solution (5 g/L). Take 2.5 g of silver nitrate (analytical reagent) into a 250 mL beaker; dissolve completely in deionized water. Transfer to a 500 mL volumetric flask; make constant volume; and store in a 500 mL amber bottle. 1 mL of this solution contains 5 mg of silver nitrate.

3.7 Sodium hydroxide solution (400 g/L). Take 100 g of sodium hydroxide (analytical reagent) into a 500 mL beaker; dissolve completely in deionized water; cool to room temperature.

Transfer to a 250 mL volumetric flask; make constant volume; mix well; and store in a plastic bottle. 1 mL of this solution contains 400 mg of sodium hydroxide.

3.8 Sodium chloride [w(NaCl)>=99.99%]. Ignite at 400 °C~450 °C for 4 h to constant weight.

3.9 Chlorine standard stock solution. Accurately take 1.6485 g of sodium chloride (3.8); place in a 250 mL beaker; dissolve in an appropriate amount of water. Transfer to a 1000 mL volumetric flask; dilute with water; make constant volume to the mark; and mix well. 1 mL of this solution contains 1 mg of chlorine.

3.10 Chlorine Standard Stock Solution A. Pipette 10.0 mL of chlorine standard stock solution (3.9) to a 100 mL volumetric flask; dilute with water; make constant volume to the mark; and mix well. 1 mL of this solution contains 100 µg of chlorine.

3.11 Chlorine Standard Solution B. Pipette 10.0 mL of Chlorine Standard Stock Solution A (3.10) to a 100 mL volumetric flask; dilute with water; make constant volume to the mark; and mix well. 1 mL of this solution contains 10 µg of chlorine.

4 Instruments

Spectrophotometer.

5 Analytical Procedures

6 Test Data Processing

The chlorine content is expressed as its mass fraction w(Cl) and calculated according to

Formula (1).

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