長光路吸収管による二酸化イオウの分光学的定量法

概要

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For rapid and sensitive determination of sulfur dioxide by means of its u.v. absorption, the use of long absorption cells of 50, 100 and 150 cm lengths is recommended. A Hitachi 207 atomic absorption spectrophotometer was modified to accommodate those long absorption cells. The standard gas from the gas cylinder was diluted properly with nitrogen, and was introduced into the absorption cell. Nitrogen is used also as the reference gas. At 207 nm the absorption is linearly proportional to the concentration of sulfur dioxide in the range from 0.2 ppm to 15 ppm almost independently of the flow rate of sample gas through the absorption cell. The detection limit of this method is 0.2 ppm. Vapors of several organic solvents and nitrogen dioxide interfere with the absorption at 207 nm.<BR>A small portion of sample gas was injected into a tube connected to the absorption cell and was passed through the absorption cell with carrier nitrogen. By this procedure, 4×10<SUP>-9</SUP> mol of pure sulfur dioxide gives 1% absorption.<BR>The Mg 2025 Å line emitted from magnesium hollow cathode lamp may also be used as the light source for this purpose.