T/SXSYSJSXH 0003-2024 Active

Scope: This standard specifies the atomic fluorescence spectrometry method for determining the effective selenium in soil using diethylenetriamine pentaacetic acid (DTPA) extraction. This standard is applicable to the determination of the effective selenium in soil; Main technical content: 4. Method principle: The effective selenium in soil is extracted using a DTPA-CaCl2-TEA buffer solution, and its content is determined by atomic fluorescence spectrometry. In a 6 mol/L hydrochloric acid medium, the selenium in the sample is reduced to tetravalent selenium. Potassium borohydride is used as a reducing agent to reduce tetravalent selenium in the hydrochloric acid medium to hydrogen selenide, which is carried into the atomizer by carrier gas for atomization. Under the irradiation of a selenium-specific hollow cathode lamp, the ground state selenium atoms are excited to a high energy state. When they deactivate and return to the ground state, they emit fluorescence with a characteristic wavelength, and the fluorescence intensity is proportional to the selenium content. 5. Interference and elimination 5.1 Transition metals such as copper at a certain concentration may interfere with the determination. Under the experimental conditions of this standard, samples containing less than 100 mg/L Cu2+, 50 mg/L Fe3+, 1 mg/L Co2+, 5 mg/L Pb2+, and 2 mg/L Mn2+ do not affect the determination. 5.2 Common anions do not interfere with the determination. 5.3 Physical interference elimination. A double-layer quartz tube atomizer is selected, with both inner and outer layers filled with argon. An outer protective layer is formed to isolate the air, preventing the ground state atoms of the elements to be determined from colliding with oxygen and nitrogen in the air, thereby reducing the influence of fluorescence quenching on the determination. 6. Reagents and materials Unless otherwise specified, analytical-grade reagents conforming to national standards are used for analy