Anhydrous ethanol absorption-gas chromatography method for determining extremely tiny amount of iodomethane in gas

Abstract

The invention belongs to a method for analyzing an iodomethane gas in environment air, and concretely relates to an anhydrous ethanol absorption-gas chromatography method for determining an extremely tiny amount of iodomethane in a gas. The method comprises the following steps: carrying out chromatographic leaching by using anhydrous ethanol with the concentration being not lower than 99.8% to absorb the iodomethane gas, determining the content of iodomethane in anhydrous ethanol by using a gas chromatograph detector to obtain the concentration of an absorption liquid, obtaining the mass of iodomethane in the absorption liquid according to the concentration of the absorption liquid, obtaining a standard sampling time according to the sampling flow, the sampling time, the sampling volume and the temperature and the gas pressure in the sampling process, and calculating to obtain the concentration of the iodomethane gas in air. The method reduces the detection limit of the iodomethane gas in the environment air, provides bases for adoption of effective protection measures for occupational health work places and workers, and provides calculating bases for chemical removal of the radioactive iodomethane gas from air in the places.

Description

technical field [0001] The invention belongs to an analysis method of methyl iodide gas in ambient air, and in particular relates to an anhydrous ethanol absorption-gas chromatography analysis method of a very small amount of methyl iodide in the gas. Background technique [0002] Methyl iodide is a nerve gas with cumulative effects that can seriously damage the human nervous system. It is generally measured quantitatively by 1,2 naphthoquinone-4 sodium sulfonate spectrophotometry (GBZ / T160.45-2007). This method is relatively mature, and the minimum detection concentration is 0.8mg / m 3 , while occupational health allows the limit concentration of methyl iodide gas in the ambient air to be 1mg / m 3 , although the standard method can qualitatively judge whether the concentration of methyl iodide gas in the ambient air exceeds the standard, due to the continuous improvement of occupational health requirements, the allowable limit concentration of methyl iodide in the ambient a...

AI Technical Summary

Problems solved by technology

There are following techniques to reduce the detection limit of methyl iodide gas, but all there are disadvantages to a certain extent: 1) use metal sodium to convert methyl iodide into iodide ion, and then measure its content with spectrophotometry, the detection limit can be reduced, but due to the introduction Sodium metal is extremely active in chemical properties and has a high risk of fire; 2) The direct analysis of methyl iodide gas method by gas chromatography has a low detection limit, but the gas collection and analysis is not easy to control and has poor stability; 3) Gas chromatography-mass spectrometry technology measures iodine Methane gas method, adsorption cold trap enrichment, low detection limit, but the instrument is expensive and maintenance costs are high, which is not conducive to the use of general units

[0003] In the nuclear field, the measurement of radioactive methyl iodide gas usually adopts the method of activated carbon adsorption and gamma spectrometer to measure its activity to determine its radioactivity, and the mass concentration of radioactive methyl iodide gas in the ambient air of the site cannot be determined

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