range
GB/T22 105 This part specifies the method for the determination of total mercury in soil by atomic fluorescence spectrometry. This part is applicable to the determination of total mercury in soil. The detection limit of this method is 0002mg/kg.
principle
The mixed reagent of nitric acid and hydrochloric acid was heated in boiling water bath to digest the soil sample, and then the mercury in the sample was reduced to atomic state by potassium borohydride (KBH) or sodium borohydride (NaBH). In the atomization process of carrier gas (gas), mercury atoms in the ground state are excited to high energy state under the irradiation of special hollow cathode lamp.
When it deactivates and returns to the ground state, it emits fluorescence with characteristic wavelength, and its fluorescence intensity is proportional to the content of mercury. Compared with the standard series, the mercury content in the sample is obtained.
Instruments and equipment
Hydride generation atomic fluorescence photometer. Mercury hollow cathode lamp. Water bath pot.
Analytical method
Sample preparation; Blank test: prepare at least 2 blank solutions for each batch of samples; Calibration curve; Reference conditions of instruments: the best parameters of different models of instruments are different, which can be selected according to the instruction manual of the instrument.
Determination: adjust the instrument to the best working state, calibrate the fluorescence intensity of each point in the standard series (calibration curve is drawn after subtracting the standard blank from the fluorescence intensity to the concentration) driven by reducing agent (3.9) and carrier liquid (3. 10), and then measure the fluorescence intensity of the sample blank and the sample; Results show
Finally, carry out precision and accuracy: when determining total mercury in soil according to this part, the absolute value of relative error shall not exceed 5%. Under the condition of repetition, the relative deviation of two independent determination results shall not exceed 65438 02%.
What is total mercury?
Total mercury refers to the concentration of mercury measured after severe digestion of unfiltered water samples, including inorganic and organic combined soluble and suspended mercury.
Physical and chemical properties of mercury
Physical properties: It is the only metal that exists in liquid state at normal temperature and pressure. Melting point -38.87C, boiling point 356.6C, density 13.59g/cm3.