GB/T 4698.25-2017Methods for chemical analysis of titanium sponge, titanium and titanium alloys - Part 25: Determination of chlorine content - Silver chlorin spectrophotometry (English PDF)

3.1

Hydrofluoric acid (1 + 4), extra-pure.

3.2

Saturated boric acid solution.

3.3

Nitric acid (1 + 1).

3.4

Acetone.

3.5

Silver nitrate solution (10 g/L).

3.6 Chlorine standard stock solution

Weigh 1.6485 g of standard sodium chloride (preliminarily calcined at 400 °C ~ 500 °C to constant mass and cooled to room temperature in a desiccator); dissolve it in water; transfer it to a 1000 mL volumetric flask; use water to dilute to the mark; mix thoroughly. 1 mL of this solution contains 1 mg of chlorine.

3.7 Chlorine standard solution

Pipette 10.00 mL of the chlorine standard stock solution (3.6) into a 100 mL volumetric flask; use water to dilute to the mark; mix thoroughly. 1 mL of this solution contains 100 µg of chlorine.

6.1 Sample

Weigh 0.50 g of sample, accurate to 0.0001 g.

6.2 Number of determinations

Perform two independent determinations; calculate the average value.

6.3 Blank test

Perform a blank test with the sample.

6.4 Determination

6.4.1

Place the sample (6.1) in a 250 mL polyethylene cup (with lid); add 10 mL of hydrofluoric acid (3.1) to dissolve at room temperature.

6.4.2

After the sample is completely dissolved, add 40 mL of saturated boric acid solution (3.2); mix well; cool it. Transfer to a 100 mL volumetric flask; use water to dilute to the mark; mix well.

6.4.3

Transfer the solution according to Table 1 to a 50 mL brown volumetric flask; add

5 mL of nitric acid (3.3); mix well; allow to stand until the solution becomes clear. Add

1.0 mL of acetone (3.4) and mix well. Add 1.0 mL of silver nitrate solution (3.5); mix well; use water to dilute to the mark; mix well.