Date of Award

Summer 1997

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Chemistry & Biochemistry

Program/Concentration

Chemistry

Committee Director

Frank E. Scully, Jr.

Committee Member

Kenneth G. Brown

Committee Member

John R. Donat

Call Number for Print

Special Collections LD4331.C45 C67

Abstract

The Environmental Protection Agency (EPA) developed the toxicity characteristic leaching procedure (TCLP) to determine the potential for unknown wastes to leach haz.ardous constituents into the environment. Methods currently being used for the extraction of semi-volatile organic compounds from aqueous TCLP leachates involve acid/base partitioning into methylene chloride. The concentrated extract is then analyzed by gas chromatography/mass spectrometry (GC/MS). The methods are either timeconsuming or labor intensive and they generate significant volumes of haz.ardous wastes themselves. Considering the haz.ards and disposal costs of methylene chloride wastes, great interest has been elicited by the EPA in other extraction techniques which would reduce the volume of solvent wastes being generated by environmental laboratories. An analytical technique utilizing solid phase extraction (SPE) followed by elution with supercritical fluid carbon dioxide (SFE) has been developed. Method development included the optimization of both the SPE and SF variables. The SPE variables consisted of type of active phase, pH, ionic strength, and volume of the TCLP leachate being extracted. The SFE variables consisted of eluent pressure, temperature, volume, and evaluation of co-solvent or modifier used. Other variables associated with the trapping of the SF-eluted compounds included type of trapping media, trapping temperature, and evaluation of the final collection solvent. The modified method has been found to show comparable detection limits, accuracy, and precision for most of the compounds evaluated while drastically decreasing extraction time and virtually eliminating the need for methylene chloride. Results of TCLP leachate extractions by the SPE-SFE method and currently used liquid solvent protocols have been compared.

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DOI

10.25777/p57q-nb78

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