| Title: | Evaluation of sequential solvent and thermal extraction followed by analytical pyrolysis for chemical characterization of carbonaceous particulate matter |
| Author(s): | Beranek J; Kozliak E; Kubatova A; |
| Address: | "University of North Dakota, Department of Chemistry, 151 Cornell Street Stop 9024, Grand Forks, ND 58202, USA" |
| DOI: | 10.1016/j.chroma.2013.01.021 |
| ISSN/ISBN: | 1873-3778 (Electronic) 0021-9673 (Linking) |
| Abstract: | "A stepwise analytical protocol is presented for recognition of uncharacterized organic chemical entities comprising carbonaceous air particulate matter (PM). In this method, thermal treatment of PM samples starts with thermal extraction (TE) using temperatures below 300 degrees C to evolve volatile low molecular weight (LMW) chemicals followed by pyrolysis (Py) of non-volatile high molecular weight (HMW) compounds to yield signature patterns of their decomposition products. Both volatile species and pyrolyzed products are characterized using gas chromatography (GC) with a mass spectrometric (MS) detection. The efficacy of sequential TE (at 200 and 300 degrees C) and Py (at 400, 500, 600, 700, 800, 900 and 1000 degrees C) was demonstrated on a defined mixture of LMW species and non-volatile polystyrene, a model HMW compound. When a solid matrix, in a form of silica or graphite particles, was introduced to this system, we determined that a solvent extraction (SE) applied prior to a sequential TE/Py-GC/MS sample analysis was an essential step to eliminate the analyte-matrix interactions, which hindered the vaporization of LMW compounds from a solid matrix resulting in a poor TE/Py separation. This SE/TE/Py-GC/MS method was then successfully applied to PM samples representing real-world PM matrices to discover several novel features of PM composition. HMW species were observed in both water-soluble (extracts) and unextractable (solid residues after an exhaustive solvent extraction) fractions of wood smoke and urban PM. The species evolving upon pyrolysis were associated with the corresponding precursor polymers, such as oxidized fragments of lignin, polysaccharides and lipids, in wood smoke PM and non-volatile anthropogenic hydrocarbons in urban PM. The proposed sequential SE/TE/Py-GC/MS protocol is capable of revealing otherwise unobserved chemical components while providing useful information on their interactions within a complex and poorly characterized PM matrix. Signature SE/TE/Py profiles, i.e., PM 'fingerprints,' provided by our approach may prove useful in source apportionment studies" |
| Keywords: | Air Pollutants/*chemistry/isolation & purification Chemical Fractionation/instrumentation/*methods Environmental Monitoring Gas Chromatography-Mass Spectrometry Organic Chemicals/*chemistry/isolation & purification Particulate Matter/*chemistry/isolation; |
| Notes: | "MedlineBeranek, Josef Kozliak, Evguenii Kubatova, Alena eng Evaluation Study Research Support, U.S. Gov't, Non-P.H.S. Netherlands 2013/02/12 J Chromatogr A. 2013 Mar 1; 1279:27-35. doi: 10.1016/j.chroma.2013.01.021. Epub 2013 Jan 12" |
