GB/T 22105.1-2008Soil quality - Analysis of total mercury、arsenic and lead contents in soils - Atomic fluorescence spectrometry - Part 1: Analysis of total mercury contents in soils (English PDF)

1 Scope

This part of GB/T 22105 specifies the atomic fluorescence spectrometry method for the determination of total mercury content in the soil.

This part applies to the determination of total mercury content in the soil.

The detection limit of the method of this part is 0.002 mg/kg.

2 Principles

The mixed reagent of nitric acid-hydrochloric acid is used to heat and digest the soil sample in a boiling water bath, and then potassium borohydride (KBH4) or sodium borohydride (NaBH4) is used to reduce the mercury contained in the sample to atomic mercury, which is introduced into the atomizer by the carrier gas (argon); under the irradiation of a special mercury hollow cathode lamp, the mercury atoms in the ground state are excited to a high-energy state; when deactivated and returned to the ground state, they emit fluorescence at a characteristic wavelength, and the fluorescence intensity is proportional to the mercury content. Compared with the standard series, the content of mercury in the sample is obtained.

2.00 mL of mercury standard intermediate solution (3.14) into a 100 mL volumetric flask, dilute to the mark with preservation solution (3.11), and shake well. The concentration of mercury in this standard solution is 20.0 ng/mL (prepare this solution for current use).

3 Reagents

Unless otherwise specified, the reagents used in this part are analytical reagents, and the test water is deionized water.

3.1 Hydrochloric acid (HCl): rho=1.19 g/mL, guarantee reagent.

3.2 Nitric acid (HNO3): rho=1.42 g/mL, guarantee reagent.

3.3 Sulfuric acid (H2SO4): rho=1.84 g/mL, guarantee reagent.

3.4 Potassium hydroxide (KOH): guarantee reagent.

3.5 Potassium borohydride (KBH4): guarantee reagent.

3.6 Potassium dichromate (K2Cr2O7): guarantee reagent.

3.7 Mercury chloride (HgCl2): guarantee reagent.

3.8 Nitric acid-hydrochloric acid mixed reagent [(1+1) aqua regia]: Mix 1 part of nitric acid (3.2) with 3 parts of hydrochloric acid (3.1), and then dilute one time with deionized water.

3.10 Carrier liquid [(1+19) nitric acid solution]: Take 25 mL of nitric acid (3.2), slowly pour it into a 500 mL volumetric flask in which there is a small amount of deionized water, dilute to the mark with deionized water, and shake well.

3.11 Preservation solution: Weigh 0.5 g of potassium dichromate (3.6), dissolve it with a small amount of water, add 50 mL of nitric acid (3.2), dilute the solution to 1000 mL with water, and shake well.

3.12 Diluent: Weigh 0.2 g of potassium dichromate (3.6), dissolve it with a small amount of water, add 28 mL of sulfuric acid (3.3), dilute the solution to 1000 mL with water, and shake well.

3.13 Mercury standard stock solution: Weigh 0.1354 g of mercuric chloride (3.7) that has been dried, dissolve it with the preservation solution (3.11), transfer it to a 1000 mL volumetric flask, and then use the preservation solution (3.11) to dilute to the mark; shake well. The concentration of mercury in this standard solution is 100 µg/mL (the able organizations can purchase the standard stock solution directly from the department recognized by the country).

3.14 Mercury standard intermediate solution: Pipette 10.00 mL of mercury standard stock solution (3.13) into a 1000 mL volumetric flask, dilute to the mark with preservation solution (3.11), and shake well. The concentration of mercury in this standard solution is 1.00 µg/mL.

3.15 Mercury standard working solution: Pipette.