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采用气相色谱分离空气和甲烷是测定土壤脱附气中微量甲烷碳同位素δ~(13)C整个实验的一个重要部分。此项分离,国外采用-70℃低温进样,我们由于设备条件所限,只能在20℃以上初温下注样。由计算得知,如果色谱分离的空气峰和甲烷峰保留时间间隔能保证在0.9分钟以上,就能使百分之百甲烷进入碳同位素测定的制样系统,为达此目的,必须选定可宜的色谱条件。
The separation of air and methane by gas chromatography is an important part of the whole experiment for the determination of trace δ13C in soil desorption gas. This separation, the use of foreign -70 ℃ low temperature injection, we are limited due to equipment conditions, only 20 ℃ above the initial injection temperature. It is calculated that if chromatographic separation of the air peak and the methane peak retention interval can be guaranteed for more than 0.9 minutes, one hundred percent methane will be allowed to enter the sample preparation system for the carbon isotope determination. For this purpose, it is necessary to select suitable chromatograms condition.