GB/T 16658-2026Determination of copper, cobalt, nickel, zinc, chromium, cadmium and lead in coal (English PDF)

5.4 Sodium sulfate solution..200 g/L. Weigh.200 g (accurate to 1

g) of anhydrous sodium sulfate into a 1000 mL beaker, add a small amount of water to dissolve, and then... Transfer to a 1000mL volumetric flask, dilute to the mark with water, and mix well. Transfer to a plastic bottle.

5.5 Copper Standard Stock Solution. 1 mg/mL. Weigh 1.0000 g (accurate to 0.0002

g) of metallic copper (mass fraction not less than 99.99%). Dissolve in a small amount of nitric acid solution with a volume ratio of (1.1). Dilute to 1000 mL with 1% nitric acid solution and mix well. Put it into a plastic bottle.

5.6 Cobalt Standard Stock Solution. 1 mg/mL. Weigh 1.0000 g (accurate to 0.0002

g) of metallic cobalt (mass fraction not less than 99.99%). Dissolve in a small amount of hydrochloric acid solution with a volume ratio of (1.1). Dilute to 1000 mL with a 1% hydrochloric acid solution and mix well. Put it into a plastic bottle.

5.7 Nickel Standard Stock Solution. 1 mg/mL. Weigh 1.0000 g (accurate to 0.0002

g) of metallic nickel (mass fraction not less than 99.99%). Dissolve in a small amount of nitric acid solution with a volume ratio of (1.1). Dilute to 1000 mL with 1% nitric acid solution and mix well. Put it into a plastic bottle.

5.8 Zinc Standard Stock Solution. 1 mg/mL. Weigh 1.0000 g (accurate to 0.0002

g) of metallic zinc (mass fraction not less than 99.99%). Dissolve in a small amount of hydrochloric acid solution with a volume ratio of (1.1). Dilute to 1000 mL with a 1% hydrochloric acid solution and mix well. Put it into a plastic bottle.

5.9 Chromium Standard Stock Solution. 1 mg/mL. Weigh 2.8288 g (accurate to 0.0002

g) of spectroscopically pure potassium dichromate into a 300 mL beaker. Add 50 mL each of water and nitric acid solution in a

1.1 volume ratio to the solution. After complete dissolution, transfer the solution to a 1000 mL volumetric flask and dilute with water to the mark. Shake well. Transfer to a plastic bottle.

5.10 Cadmium Standard Stock Solution. 1 mg/mL. Weigh 1.0000 g (accurate to 0.0002

g) of metallic cadmium (mass fraction not less than 99.99%) into... Add 50 mL of nitric acid solution (

1.1 volume ratio) to a 300 mL beaker. After complete dissolution, transfer the solution to a 1000 mL volumetric flask and dilute with water. Pour to the mark and shake well. Transfer to a plastic bottle.

5.11 Lead Standard Stock Solution. 1 mg/mL. Weigh 1.0000 g (accurate to 0.0002

g) of metallic lead (mass fraction not less than 99.99%) into... Add 50 mL of nitric acid solution (

1.1 volume ratio) to a 300 mL beaker. After complete dissolution, transfer to a 1000 mL volumetric flask and dilute with water. Fill to the mark and shake well. Transfer to a plastic bottle.

5.12 Copper, cobalt, and nickel mixed standard working solution. 20 µg/mL each. Accurately pipette the copper standard stock solution (5.5) and the cobalt standard stock solution. (5.6) and 10 mL of nickel standard stock solution (5.7) were placed in a 500 mL volumetric flask and diluted to the mark with 2% nitric acid solution. Shake well. Transfer to a plastic bottle.

5.13 Cadmium and lead mixed standard working solution. 20 µg/mL each. Accurately pipette the cadmium standard stock solution (5.10) and the lead standard stock solution. (5.11) Dilute 10 mL of each solution in a 500 mL volumetric flask with 1% nitric acid solution to the mark and shake well. Transfer to a plastic bottle.

5.14 Zinc standard working solution. 50 µg/mL. Accurately pipette 25 mL of zinc standard stock solution (5.8) into a 500 mL volumetric flask, and use a syringe... Dilute a 2% nitric acid solution to the mark, shake well, and transfer to a plastic bottle.

5.15 Chromium Standard Working Solution. 20 µg/mL. Accurately pipette 10 mL of the chromium standard stock solution (5.9) into a 500 mL volumetric flask, and use a syringe... Dilute a 1% nitric acid solution to the mark and shake well. Transfer to a plastic bottle.

Note. Standard stock solutions for copper, cobalt, nickel, zinc, chromium, cadmium, and lead may also use commercially available certified reference materials with matching concentrations.

5.16 Acetylene. Purity not less than 99.9%.

6.3 Analytical balance. graduation value

0.1 mg.

6.4 Heating plate. Temperature controllable from room temperature to 300°C.

6.5 Muffle furnace. Equipped with a temperature control device, thermocouples, and a pyrometer, capable of maintaining a temperature of (500±10)°C. The furnace chamber has sufficient constant temperature. The upper part of the rear wall of the furnace has a chimney with a diameter of 25mm~30mm, and the lower part has an insertion point located 20mm~30mm from the bottom of the furnace. The thermocouple orifice. There is a 20mm diameter vent hole on the furnace door.

6.6 Polytetrafluoroethylene crucible. 30 mL capacity.

6.7 Ash dish. Porcelain, rectangular, bottom base length 45mm, bottom base width 22mm, top base length 55mm, top base width 25mm, height 14mm.

7.1.1 Accurately weigh (2±0.1) g (accurate to 0.0002

g) of general analytical test coal sample into an ash dish, spread it evenly, place it in a muffle furnace, and heat it in a self-heating furnace. However, with proper ventilation and a 15mm gap left in the furnace door, the furnace was slowly heated from room temperature to (500±10)°C, and then burned at this temperature until no black residue remained. Remove and cool until the colored particles are removed (at least 4 hours).

Note. Weigh 1g of coal sample when the ash content on an air-dried basis is greater than 30%.

7.1.2 Transfer the entire ash sample (7.1.1) into a polytetrafluoroethylene crucible, moisten it with a small amount of water, add 4 mL of perchloric acid and 10 mL of hydrofluoric acid, and place it in a container. Heat slowly on a hot plate at a low temperature (not exceeding 250°C) until nearly dry. Remove the crucible and let it cool slightly, then add 10 mL of hydrofluoric acid and continue heating on the hot plate. Heat on a hot plate until all white smoke is emitted. Remove the crucible, let it cool slightly, add 10 mL of nitric acid solution (5.3) and 10 mL of water, and heat on a hot plate until nearly... Boil and maintain the temperature for 2 minutes. Remove the crucible and transfer the solution from the crucible to a 100 mL volumetric flask using hot water. Cool to room temperature and dilute with water to the mark. Shake well. This solution is the sample solution.

7.2 Preparation of Sample Blank Solution A sample blank solution should be prepared simultaneously for each batch of samples digested. The preparation of the sample blank solution is the same as that of the previous batch, except that no ash sample is added. 7.1.2.

7.3 Preparation of the sample solution to be tested

7.3.1 Sample solutions for copper, cobalt, nickel, zinc, cadmium and lead. namely, sample solutions (7.1.2) and blank solutions (7.2).

7.3.2 Chromium test sample solution. Accurately pipette 25 mL each of the sample solution (7.1.2) and the blank solution (7.2) into a 50 mL volumetric volumetric precipitate. Add

7.5 mL of sodium sulfate solution to the bottle, dilute with water to the mark, and shake well.

7.4 Preparation of a series of standard solutions

7.4.1 Copper, Cobalt, and Nickel Standard Solutions. Take six 100mL volumetric flasks and add the mixed standard working solution of copper, cobalt, and nickel (5.12) to each flask. 0 mL,

5.0 mL, and 4 mL of nitric acid solution (5.3), dilute with water to the mark, and shake well.

7.4.2 Cadmium and Lead Standard Solutions. Take six 100mL volumetric flasks and add 0mL of each of the cadmium and lead mixed standard working solution (5.13). Add

5.0 mL, and 4 mL of nitric acid solution (5.3), dilute with water to the mark, and shake well.

7.4.3 Zinc series standard solutions. Take six 100mL volumetric flasks and add 0mL and 1.0mL of zinc standard working solution (5.14) to each flask. Add

5.0 mL, and 4 mL of nitric acid solution (5.3), dilute with water to the mark, and shake well.

7.4.4 Chromium series standard solutions. Take six 100mL volumetric flasks and add 0mL, 1.0mL, and 1.0mL of chromium standard working solution (5.15) to each flask. Add

5.0 mL, and 4 mL of nitric acid solution (5.3), and 15 mL of sodium sulfate solution, dilute with water to the mark, and shake well.

7.5 Measurement

7.5.1 Determination of Instrument Operating Conditions. The flame gas used in the instrument is acetylene-air. Except for the analytical lines for each element specified in Table 1. In addition, other instrument parameters-lamp current, bandwidth, burner height, and gas and auxiliary gas flow rates-should be adjusted to their optimal values through testing. Excellent value. GB/T 16658-2026. Methods for the determination of copper, cobalt, nickel, zinc, chromium, cadmium and lead in coal ICS

21 National Standards of the People's Republic of China Replaces GB/T 16658-2007 and GB/T 19225-2003 Methods for determining copper, cobalt, nickel, zinc, chromium, cadmium, and lead in coal Published on 2026-03-

31 Implemented on October 1, 2026 State Administration for Market Regulation The State Administration for Standardization issued a statement.