，其日變化曲線呈雙峰形。

甲烷柱直接法測(cè)定大氣中的非甲烷烴 圖片：


Direct determination of non-methane hydrocarbons in the atmosphere by methane column
Direct determination of non-methane hydrocarbons in the atmosphere by methane column direct method:

Stationary phase: polymer pellet
GDX-502, 2m*3mm, 2m*4mm, 2m*1/8, 60-80 mesh
Methane column

Total hydrocarbon column
2m*3mm, 2m*4mm, 2m*1/8, silanized glass microspheres


On-line monitoring and analysis of 56 non-methane hydrocarbons (NMHCs) in the four seasons. From the compositional point of view, the average concentration of total NMHCs in the four seasons was 23.6×10-9, showing the characteristics of winter>autumn>summer and spring. The highest proportion of alkanes (65.4%~74.7%), followed by aromatic hydrocarbons (13.3%~21.7%) and olefins (7.1%~11.6%), propane, toluene, ethane, n-hexane, n-butane, acetylene, 2- Methyl pentane, isobutane, ethylene and 3-methylpentane are the highest concentrations of 10 species. Correlation and daily variation analysis indicate that NMHCs in the atmosphere of Shenzhen are subject to motor vehicles, solvent volatilization-related industrial sources, and plant release. The combined effects of multiple sources, among which toluene, 2-methylpentane, 3-methylpentane and n-hexane are most affected by industrial sources, and isoprene mainly comes from natural sources.
Tengzhou Haohao Chromatography Instrument Technology Service Co., Ltd. introduced the determination of non-methane hydrocarbons in the atmosphere by direct method at two monitoring points. The detection limit of the determination method was up to 0.0065 mg/m^3. In the linear range of 0-10 mg/m^3, the linear correlation coefficient was 0.9995, and the relative standard anxiety difference was 2.8%. The results show that the daily variation curve is bimodal due to the influence of atmospheric inversion layer, industrial emission source and automobile exhaust on the concentration change of non-methane hydrocarbons.

Determination of non-methane hydrocarbons in the atmosphere by direct methane column method