Soil and sediment mercury, arsenic, selenium, bismuth, and antimony atomic fluorescence method (1)

(1) Scope of application

Microwave digestion/atomic fluorescence method is suitable for determining the content of mercury, arsenic, selenium, bismuth and antimony in soil and sediment

Application of standard analytical methods: "Marine Monitoring Specification Part 3: Sample Collection, Storage and Transportation" (GB17378.

(2) Method principle

After the sample is digested by microwave, the test solution enters the atomic fluorescence photometer.

(3) Reagents and materials

(1) Ultrapure water: resistivity greater than 18.

(2) Nitric acid, hydrochloric acid , potassium borohydride : pure superior grade

(3) Sulfur, sodium hydroxide : analytically pure

(4) Potassium borohydride solution A, p=2g/L: Weigh 0.

(5) Potassium borohydride solution B, p=20g/L: Weigh 0.

(6) Thiourea solution p=100g/L: Take 10g of thiourea , dissolve it with pure water, and dilute to 100mL

(7) Standard solution of arsenic, selenium, antimony and bismuth (1000pg/L), produced by AccuStandard, USA

(4) Instruments and equipment

(1) Atomic fluorescence spectrophotometer: Atomic fluorescence spectrophotometer with mercury, arsenic, smash, bismuth, and antimony element lamps that should meet the requirements of GB/T21191

(2) Microwave digestion instrument: The model is ETHOS TC

(3) Constant temperature water bath device

(4) Analytical balance: the accuracy is 0.

(5) Commonly used equipment in other laboratories

(5) Sample preparation

1.

According to the "Technical Specifications for Soil Environmental Monitoring" (HJ/T166-2004) and "Marine Monitoring Specifications Part 3: Sample Collection, Storage and Transportation" (GB17378.
3-2007), the soil samples and sediment samples were air-dried and broken.
, Sieved, and preserved
.
Calculate the moisture content of soil and sediment samples according to "Gravimetric Method for Determination of Soil Dry Matter and Moisture" (HJ613) and "Marine Monitoring Specification Part 5: Sediment Analysis" (GB17378.
5-2007)
.

2.
Digestion of the sample

Weigh 0.
1～0.
5g sample in a microwave digestion tank, wet it with a small amount of water, add 6mL hydrochloric acid and 2mL nitric acid in a fume hood , mix well, and make the sample fully contact the digestion solution
.
After the violent chemical reaction is over, put it into the microwave digestion apparatus, set up the microwave digestion apparatus and run it according to the recommended heating program in Table 5-52
.
After the program has finished cooling, take out the microwave digestion tank and release the pressure in a fume hood, filter with quantitative filter paper and transfer it into a 50mL volumetric flask, use experimental water to make the volume up to the mark, and mix well
.

Table 5-52 Heating program of microwave digestion