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Field Determination of Organics from Soil and Sludge using Sub-critical Water Extraction Coupled with Solid Phase Extraction

EPA Grant Number: R825368
Title: Field Determination of Organics from Soil and Sludge using Sub-critical Water Extraction Coupled with Solid Phase Extraction
Investigators: Hawthorne, Steven B.
Institution: University of North Dakota
EPA Project Officer: Stelz, Bill
Project Period: October 1, 1996 through September 30, 1999
Project Amount: $279,935
RFA: Analytical and Monitoring Methods (1996)
Research Category: Environmental Statistics , Ecological Indicators/Assessment/Restoration

Description:

The primary purpose of the proposed investigations is to couple well-known extraction methods for water, solid phase extraction (SPE) and solid phase microextraction (SPME), with subcritical water extraction of soils and sludges to allow field-portable water methods to be applied to contaminated solids.

For water samples, both SPE and SPME can be used to extract and concentrate organics in the field for subsequent analysis (e.g., field-portable GC), but are not applicable to extracting organic pollutants from solid samples. If organic pollutants on soils and sludges could be efficiently transferred to water, both SPE and SPME could be very useful for field determinations of organic pollutants from solids. We have demonstrated that subcritical water (hot water maintained as a liquid by a few bar pressure) is an excellent solvent to quantitatively extract polar and non-polar organics from soils and sludges. Subcritical water extractions can be highly selective; polar organics extract at lower temperatures (e.g., phenols and amines extract at 50 to 100oC), and non-polar organics extract at high temperatures (e.g., 200 to 250?C). By simply heating water under low pressure, solubilities of polar organics increase dramatically, and even non-polar organics such as PAHs can increase solubilities by >106-fold. Preliminary experiments have demonstrated that coupling subcritical water extraction with SPE and SPME can provide an extremely simple, rapid, and inexpensive method to determine organic pollutants found on soils, sediments, and sludges. Quantitative results have been obtained with total sample preparation (including extraction from the solid and SPE or SPME sorption) of ca. 30 minutes. Detection limits of <ppb are easily obtained. Based on these initial results, the proposed investigations will: 1) develop the use of subcritical water coupled to SPE (exhaustive extraction) for the quantitative determination of polar and non-polar organics from soils and sludges; 2) develop the use of subcritical water extraction coupled with SPME (equilibrium extraction) for the rapid and quantitative determination of polar and non-polar organics from soils and sludges; 3) optimize the selectivity of the extractions based on water extraction temperature and on SPE and SPME sorbent selectivity; and 4) demonstrate the best approaches in the field and compare results to conventional EPA extraction and analysis methods.

Based on preliminary studies, it is expected that the proposed investigations will yield an extremely simple (requiring only an extraction cell and oven), inexpensive, and field-portable approach to utilizing SPE and SPME with subcritical water for the extraction and quantitative determination of polar and non-polar organics from contaminated solids and semi-solids.

Publications and Presentations:

Publications have been submitted on this project: View all 16 publications for this project

Journal Articles:

Journal Articles have been submitted on this project: View all 6 journal articles for this project

Supplemental Keywords:

water, water extraction, methods, field analysis, detection limits, inexpensive methods, soils, solids. , Ecosystem Protection/Environmental Exposure & Risk, Water, Scientific Discipline, Waste, Physics, Chemistry, Environmental Chemistry, Contaminated Sediments, Monitoring/Modeling, water extraction, hydrocarbons, gas chromatography, field portable monitoring, sucritical water , solid phase microextraction, contaminated sediment, organic contaminants, PAH, soil, organics

Progress and Final Reports:
1997 Progress Report
Final Report

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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