GB/T 6730.80-2019 in English

Standard background and significance

GB/T 6730.80-2019 "Determination of mercury (Hg) content in iron ore - Cold atomic absorption spectrometry" is an important part of the national standard of the People's Republic of China, mainly for the determination of mercury (Hg) content in iron ore.

Scope and applicability of the standard

Determination principle and steps

1. Microwave digestion instrument is used for acidification and decomposition of the sample, using a mixed acid system of hydrochloric acid, nitric acid and hydrofluoric acid.
2. Under acidic conditions, stannous chloride is used to reduce mercury ions to mercury vapor.
3. The mercury content is determined at a wavelength of 253.7 nm using a cold atomic absorption spectrometer.

Instrument and reagent requirements

The standard specifies detailed instrument and reagent requirements, including:

• Cold atomic absorption spectrometer: detection limit not greater than 0.05 μg/L, linear correlation coefficient not less than 0.997.
• Microwave digestion instrument: equipped with 100 mL polytetrafluoroethylene sealed digestion tank.
• Analytical balance: sensitivity is 0.0001 g.

Result calculation and precision analysis

The mercury content (mass fraction) was calculated according to formula (1):

w(Hg) = [(ρ - ρ₀) × f × V] / m × 10⁻⁷

Wherein: ρ is the mass concentration of mercury in the test solution, ρ₀ is the mass concentration of mercury in the blank test solution, f is the dilution factor of the sample solution, V is the total volume of the test solution, and m is the mass of the sample.

Precision and Correctness Verification

Implementation Recommendations

To ensure the effective implementation of the standard, it is recommended that:

• The laboratory should have professional equipment and operators.
• Regularly calibrate the instrument and perform blank tests.
• Use certified standard samples for method validation.
• Establish a complete experimental record and data management system.