GB/T 4324.23-2012Methods for chemical analysis of tungsten - Part 23: Determination of sulfur content - The combustion-conductometric titration and high frequency combustion-infrared absorption method (English PDF)

4.1 Method summary

Sample in an oxygen stream of high temperature combustion generates sulfur dioxide by iodine absorption, conductivity method.

4.2 Reagents and materials

4.2.1 copper oxide

blank value is high when dealing with the following manner. The copper cable was cut, washed through the outer layer of dirt dilute nitric acid, washed with distilled water nitrate

Acid, dried, placed in a porcelain boat, under flowing oxygen at 1250 °C calcined 10min, remove, pour in the alloy mortar, hammer mill, over 0.147mm sieve

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4.2.2 Zinc oxide

zinc oxide loaded into the AR porcelain evaporating dish at 800 °C ~ 900 °C high temperature furnace firing 2h, then cool, crush, through

Over standard 0.147mm sieve. If the blank does not meet the requirements, it can be loaded inside a porcelain boat, by 1250 °C calcined under flowing oxygen 15min, removed,

Cooled and pulverized by standard 0.147mm sieve and set aside.

4.2.3 Saturated iodine solution

Weigh 5g iodine, placed in pre-filled with double distilled water 2000mL brown bottle, shake regularly, place a few days later, electricity

Less than 20µS guide values can be used.

4.2.4 alkaline potassium permanganate solution (30g/L)

Weigh 3g of potassium permanganate dissolved in 100mL of potassium hydroxide solution (100g/L) of.

4.2.5 sulfur standard solution

4.2.5.1 preparation

Weigh 0.4430g benchmark anhydrous sodium sulfate (advance after 105 °C ~ 110 °C baking 1h, placed in a desiccator, cooled to room

Temperature), was dissolved in double distilled water and transferred to 1000mL volumetric flask, dilute with water to volume, and mix. This solution 1mL containing about 0.1mg sulfur.