| Title: | Optimization of the solvent-based dissolution method to sample volatile organic compound vapors for compound-specific isotope analysis |
| Author(s): | Bouchard D; Wanner P; Luo H; McLoughlin PW; Henderson JK; Pirkle RJ; Hunkeler D; |
| Address: | "Centre for Hydrogeology and Geothermics (CHYN), University of Neuchatel, Rue Emile Argand 11, 2000 Neuchatel, Switzerland. Electronic address: dbouchard@sanexen.com. Centre for Hydrogeology and Geothermics (CHYN), University of Neuchatel, Rue Emile Argand 11, 2000 Neuchatel, Switzerland. Chevron Energy Technology Company,1400 Smith Street, Houston, TX 77002, USA. Pace Analytical Energy Services, LLC, 220 William Pitt Way, Pittsburgh, PA, 15238, USA. DuPont de Nemours,6324 Fairview Road, Charlotte, NC 28210, USA" |
| DOI: | 10.1016/j.chroma.2017.08.059 |
| ISSN/ISBN: | 1873-3778 (Electronic) 0021-9673 (Linking) |
| Abstract: | "The methodology of the solvent-based dissolution method used to sample gas phase volatile organic compounds (VOC) for compound-specific isotope analysis (CSIA) was optimized to lower the method detection limits for TCE and benzene. The sampling methodology previously evaluated by [1] consists in pulling the air through a solvent to dissolve and accumulate the gaseous VOC. After the sampling process, the solvent can then be treated similarly as groundwater samples to perform routine CSIA by diluting an aliquot of the solvent into water to reach the required concentration of the targeted contaminant. Among solvents tested, tetraethylene glycol dimethyl ether (TGDE) showed the best aptitude for the method. TGDE has a great affinity with TCE and benzene, hence efficiently dissolving the compounds during their transition through the solvent. The method detection limit for TCE (5+/-1mug/m(3)) and benzene (1.7+/-0.5mug/m(3)) is lower when using TGDE compared to methanol, which was previously used (385mug/m(3) for TCE and 130mug/m(3) for benzene) [2]. The method detection limit refers to the minimal gas phase concentration in ambient air required to load sufficient VOC mass into TGDE to perform delta(13)C analysis. Due to a different analytical procedure, the method detection limit associated with delta(37)Cl analysis was found to be 156+/-6mug/m(3) for TCE. Furthermore, the experimental results validated the relationship between the gas phase TCE and the progressive accumulation of dissolved TCE in the solvent during the sampling process. Accordingly, based on the air-solvent partitioning coefficient, the sampling methodology (e.g. sampling rate, sampling duration, amount of solvent) and the final TCE concentration in the solvent, the concentration of TCE in the gas phase prevailing during the sampling event can be determined. Moreover, the possibility to analyse for TCE concentration in the solvent after sampling (or other targeted VOCs) allows the field deployment of the sampling method without the need to determine the initial gas phase TCE concentration. The simplified field deployment approach of the solvent-based dissolution method combined with the conventional analytical procedure used for groundwater samples substantially facilitates the application of CSIA to gas phase studies" |
| Keywords: | "Benzene/analysis Environmental Monitoring/*methods Gases/chemistry Groundwater/chemistry Isotopes/*analysis Limit of Detection Solvents/chemistry Volatile Organic Compounds/*analysis/chemistry Water Pollutants, Chemical/analysis Air analysis Air sampling;" |
| Notes: | "MedlineBouchard, Daniel Wanner, Philipp Luo, Hong McLoughlin, Patrick W Henderson, James K Pirkle, Robert J Hunkeler, Daniel eng Netherlands 2017/09/25 J Chromatogr A. 2017 Oct 20; 1520:23-34. doi: 10.1016/j.chroma.2017.08.059. Epub 2017 Aug 24" |
