GB/T 39538-2020Determination of arsenic, selenium and mercury in coal - Hydride generation-atomic fluorescence spectrometry (English PDF)

3.1 Method summary

The coal sample is mixed with Eschka reagent and burned, and the burned substance is dissolved with hydrochloric acid. When arsenic is measured, thiourea-ascorbic acid is used to reduce pentavalent arsenic to three.

When determining selenium, use hydrochloric acid heating to reduce hexavalent selenium to tetravalent selenium, then use sodium borohydride as a reducing agent, and argon as a carrier gas to reduce the result

The obtained gaseous hydride is introduced into an atomizer and measured by an atomic fluorescence spectrometer.

3.2 Reagents and materials

Unless otherwise specified, only use reagents and distilled or deionized water or equivalent purity water confirmed to be analytically pure in the analysis.

3.2.1 Ashika reagent (hereinafter referred to as Aldrin)

commercially available, or mix 2 parts by mass of light magnesium oxide and 1 part by mass of anhydrous sodium carbonate

After grinding to a particle size of less than 0.2mm, store it in a closed container.

3.2.2 Argon gas

purity above 99.99%.

3.2.3 Hydrochloric acid

the relative density is 1.18.

3.2.4 Hydrochloric acid solution

50mL/L, add 50mL of hydrochloric acid (3.2.3) to an appropriate amount of water, and then dilute to 1L with water.

3.2.5 Sulfuric acid solution

c(1/2H2SO4)=6mol/L. Measure 167 mL of sulfuric acid with a relative density of 1.84 and slowly add it to an appropriate amount of water.

Stir while adding, then dilute to 1L with water.

3.2.6 Sodium hydroxide solution

5g/L. Weigh 5.0g of sodium hydroxide and dissolve in 1L of water.

3.2.7 Sodium hydroxide solution

c(NaOH)=6mol/L. Weigh 48.0g of sodium hydroxide dissolved in a small amount of water and dilute to.200mL.

3.2.8 Sodium borohydride solution

10g/L. Weigh 10.0g of sodium borohydride and dissolve it in 1L of sodium hydroxide solution (3.2.6) and prepare it before use.

3.2.9 Thiourea-ascorbic acid solution

50g/L. Weigh 5.0 g of thiourea and 5.0 g of ascorbic acid, dissolve them in 100 mL of water, and prepare them before use.

3.2.10 Arsenic standard stock solution

100µg/mL. Accurately weigh the premium grade pure arsenic trioxide that has been dried at 105°C~110°C for about 2h

0.1320g dissolved in 2mL sodium hydroxide solution (3.2.7), add about 50mL water, after it is completely dissolved, add 2.5mL sulfuric acid solution […]