GB/T 38292-2019Determination of mercury in plastic materials (English PDF)

3.1 Principle

Pulverize the sample, weigh a certain amount of sample powder, digest it by microwave digestion, the digestion solution enters the atomic fluorescence instrument, and the potassium borohydride solution

Under reduction, mercury atom vapor is generated. These gases form ground-state atoms in an argon-hydrogen flame and are produced under the excitation of light emitted by a hollow cathode lamp

Atomic fluorescence, the intensity of atomic fluorescence is proportional to the mercury content in the sample, and is quantified by external standard method.

3.2 Reagent

Warning-tetrafluoroboric acid is highly corrosive and irritating, and can cause burns to the human body. Pay attention to protection during the dropping process.

Unless otherwise stated, the reagents used should be of superior grade pure and above, and the water used should meet the requirements of first-class water specified in GB/T 6682.

3.2.1

Nitric acid (HNO3), analytically pure.

3.2.2

Hydrochloric acid (HCl), analytically pure.

3.2.3

Hydrogen peroxide (H2O2), analytically pure.

3.2.4

Tetrafluoroboric acid (40%), analytically pure.

3.2.5

Potassium borohydride (KBH4), analytically pure.

3.2.6

Potassium hydroxide (KOH), analytically pure.

3.2.7

Potassium dichromate (K2CrO4), analytically pure.

3.2.8 Potassium borohydride (KBH4) solution

Weigh 0.5g of potassium hydroxide into a beaker containing 100mL of distilled water, stir with a glass rod

After complete dissolution, add 1.0 g of potassium borohydride weighed and stir to dissolve. This solution should be prepared daily. Can also use sodium hydroxide, borohydride

Sodium is used to prepare sodium borohydride solution.

3.2.9 Hydrochloric acid solution (5 95)

Measure 50mL of hydrochloric acid, add 950mL of water, and mix.

3.2.10 Potassium dichromate solution (fixing solution)

Dissolve 0.5g potassium dichromate in 950mL water, then add 50mL nitric acid and mix well.

3.2.11

Mercury element standard stock solution (1000mg/L or other concentration). use a certain concentration that has been certified by the state and granted a standard substance certificate […]