Sampling Method Of Solid Phase Extraction For Monitoring Of VOCs In Ambient Air

Pollution problems of volatile organic compounds (VOCs) have aroused widespread concern in academic circles at home and abroad, especially for the effect of secdary fine particles in the air, so it is urgent to control emissions of VOCs. Now main monitoring methods include thermal analysis, digital tank and the recovery bag. These methods are mainly applicable to high concentration of VOCs sample collection, but it is difficult to sample the low concentration and trace VOCs. VOCs are mainly from unorganized emissions, despite the low concentration, but its origin is widespread, causing serious pollution to the environment, especially the contribution to PM2.5 of inestimable, Therefore, the urgent need for research on monitoring technology of VOCs emission.In this paper using a new low volume air sampler, using 50 mg solid phase extraction column to sample 53 VOCs, the analysis of elution volume, extraction recovery, and sampling efficiency, main results are as followed:(1) Elution volume:elution solvent is n-hexane, elution volume of ENV+ cartridge is 1 mL,38 VOCs can be eluted;(2) Elution recovery:one of 38 VOCs is lower,33.86%; 37 VOCs are 91.19-203.66%;(3) Breakthrough:17 kinds of VOCs less than 5%, does not penetrate the columella of extraction, extraction column can better adsorption of the compounds;(4) Sampling efficiency:6 VOCs are<20%; 7 VOCs are 24.81%-49.32%; 16 VOCs are 50%-70%; naphthalene is 118.46%;(5) According to four indicators of elution volume, elution recovery, breakthrough and sampling efficiency, the method can be used for qualitative analysis of 16 VOCs, qualitative and quantitative analysis of naphthalene.Continuous monitoring of 7 VOCs in ambient air, the maximum concentration is 323.37 ng/m3.Average concentration is 33.48 ng/m3, lower than 10 cities (695.54 ng/m3).The method can monitor VOCs in ambient air. Compared with the conventional method, the advantages are simple operation, sample collection and analysis of low cost, wide applicability, and it can meet the needs of environmental monitoring and scientific research departments.