Mass Spectrometry Identification of VOCs in the Atmosphere by a Combination of Cartridge Adsorption and SPME

Integration of cartridge adsorption and SPME for sampling with library search and deconvolution for data elaboration. The identification of volatile organic compounds (VOCs) in the atmosphere is a very important task for environmental control. Air is a fundamental environmental matrix as everybody, humans, animals, plants, are in continuous contact with it. Moreover it is the most important carrier for transportation of pollution. The analysis of volatile pollutants is complicated by the fact that they are present at low concentration in a complex matrix, so that the samples need to be enriched prior to analysis. The sampling is performed by adsorption on cartridges contaning Tenax TA as a sorbent material (Supelco ORBO 402). Analysis is performed by SPME of the headspace above the sorbent material, after transferring in a vial, coupled to a GC-MS system (Varian 3800 gas-chromatograph and Saturn 2000 ion trap mass spectrometer), using both EI and CI ionization. Data are elaborated by a combination of library search (NIST 2002) and a deconvolution program (AMDIS 32) for maximum reliability. The method has been used for the identification of bad smelling organic volatile compounds in the area of a solid waste landfill. The species present at the highest levels were at the ppt level, and the classic solvent desorption methods were able to reveal only a few components. The use of our integrated approach allowed to identify more than one hundred organic compounds, including idrocarbons, carbonyl compounds, carboxylic acids and esters, alcohols, chlorinated compounds and some natural terpenoids. It has also used to make a comparison of the quality of the air in different areas and situations. In particular, we collected samples, using the same adsorption time and flow rate, in two different sites in a town, a main road during the rush hour and a pedestrian precinct, in a natural reserve, in a countryside location and in a resinous trees wood. The results obtained clearly indicate the power of these approach for environmental qualitative analysis