Impact/Purpose:

The primary technical goal is to apply SFE to a variety of environmental sampling and analytical problems and to develop an alternative to existing sampling/analysis technology based upon the PS1 sampler and subsequent Soxhlet extraction. Additionally, we will replace standard liquid injection GC-MS methodology with a large volume injection (LVI-GC-MS) method.

Description:

EPA Regional Laboratories are currently using high volume samplers with a combination of filter and sorbent vapor trap to collect large volume samples (250 liter/min for 24 hours) of semi-volatile organic compounds (SVOCs) and non-volatile organic compounds (NVOCs). These are subsequently extracted using solvents such as methylene chloride or hexane/ether (typically 250 -500 ml/sample). This is a time consuming process taking typically 18 hours/sample and generating large volume of waste solvent in the form of vapors vented through a fume hood. The sampling devices are large and noisy, and the sample format requires special in-field handling prior to shipping. The research to be performed here will investigate the possibility of replacing this technology with the more environmentally friendly CO2 supercritical fluid extraction (SFE) process, and in reducing the physical size of the sampler and sampling cartridges. An expected bonus of this conversion will be cost reduction through streamlining of laboratory procedures and reduction of logistics costs of shipping and handling.

Record Details:

Record Type:PROJECT

Start Date:10/01/2000

Completion Date:09/01/2003

Record ID: 56163

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Project Information:

Progress :The SFE project has been started again after being dormant for a year. A number of related yet separate technical issues have been studied: We have investigated the compatibility of four commonly used air sampling adsorbent materials (Tenax-GC, Tenax-GR, XAD-2, and Carboxen 563) with the rigors of repeated SFE procedures; we have studied the relative extraction efficiencies of SFE vs. Soxhlet using carpet samples as the solid matrix; we have developed LVI-GC-MS for analysis of blood extracts and are beginning to apply the methodology to pesticide and SVOCs analysis. Some related outputs from these investigations are:

Bowyer, J.R. and J.D. Pleil, 1995. "Supercritical Fluid Extraction as a Means of Cleaning and Desorbing Common Air Sampling Sorbents", Chemosphere, 31:3 (1995) 2905-2918.

Bowyer, J.R. and J.D. Pleil, 1997. "Comparison of Supercritical Fluid Extraction and Soxhlet Extraction of organic compounds from carpet samples", Journal of Chromatography A 787(1&2): 171-179.

Liu, S. and J.D. Pleil, 1999. "Method for Liquid/liquid extraction of blood surrogates for assessing human exposure to jet fuel", Journal of Chromatography B, Biomedical Applications, 728: 193-207.

Liu, S. and J.D. Pleil, 2000. "Optimized determination of trace jet fuel VOCs in human blood using in-field liquid-liquid extraction with subsequent laboratory GC-MS analysis and on-column large volume injection", Journal of Chromatography B, Biomedical Applications (in press)

Childers, J.W., C. Witherspoon, L.B. Smith and J.D. Pleil, 2000. "Instrument evaluation for real-time and integrated measurement of particle bound polycyclic aromatic hydrocarbons (PAH) from aircraft exhaust", Environmental Health Perspectives (in press - Sept. issue).

Brande, R.E. and J.W. Childers, 2000. Final Report for WA-108, Contract 68-D5-0049, ManTech Environmental Technology, Inc. "Regional Sampling and Analytical Methods Research for SFE as an Alternative to Soxhlet Extraction for trace-level SVOCs and NVOCs", TR-4423-00-01, June 30, 2000, Mantech Environmental Technology, Inc., PO Box 12313, Research Triangle Park, NC 27709.



Relevance :The EPA Regions need a faster, more accurate measurement method for ambient trace-level SVOCs and NVOCs to allow them to reduce the physical size of the samplers and sampling cartridges and to avoid generating large volumes of organic waste. To date, the EPA Regional Laboratories are using high volume samplers with a combination of filter and sorbent vapor trap to collect large volume samples (250 liter/min for 24 hours). These are subsequently extracted using solvents such as methylene chloride or hexane/ether (typically 250 -500 ml/sample with an additional 500 ml/cartridge for cleanup). This is a time consuming process taking typically 18 hours/sample and generating large volume of waste solvent in the form of vapors vented through a fume hood. The sampling devices are large and noisy, and the sample format requires special in-field handling prior to shipping. The research to be performed here will investigate the possibility of replacing this technology with the more environmentally friendly CO2 SFE extraction process, and in reducing the physical size of the sampler and sampling cartridges. To accommodate the potentially smaller absolute sample size, the analytical system/methodology needs to be improved in sensitivity. LVI-GC-MS will be employed as recently developed in our laboratory. The eventual impact will be to develop turn-key, commercially available methods and instrumentation for replacing Soxhlet extraction at the regional level that is faster, cheaper, and much more environmentally friendly than existing methodology.

Clients :EPA Regional Laboratories

Project IDs:

ID Code :4873

Project type :OMIS