LE3 .A278 2010

2010

Tong, Anthony

Acadia University

Bachelor of Science

Honours

Environmental Science

Earth & Environmental Sciences

The development of modern analytical instrumentation has made identifying and quantifying environmental contamination increasingly easier, however little improvement has been made to sample preparation as in the case of solid samples ( soils and sludges). When preparing solid samples one currently has to choose either expensive or time- consuming methods. Soxhlet extractions, a traditional technique, continue for a period of 16 - 24 hours. Innovation in the realm of extraction has been mostly to change the characteristics of Soxhlet extraction ( under high pressure, under high temperature, or using a supercritical fluid) to reduce the time needed for the extraction. These alterations often require expensive equipment. Therefore the Soxhlet extraction method itself is still widely in use, currently. It was hypothesized that one could complete an extraction in a reasonable time frame without the cost associated with specialized equipment by using a system of solvents. The system of solvents used for this study was methanol, toluene, and water. The contaminants analyzed were sixteen polycyclic aromatic hydrocarbons ( PAHs). Methanol was used to extract contaminants from the soil sample and toluene was added to preferentially keep organic contaminants ( in this case PAHs). When water was added, it separated the toluene layer from the methanol, as toluene is insoluble in water. In this way the toluene layer rises to the top and can be removed and analyzed using gas chromatography coupled with mass spectrometry. Between each addition of solvent, the sample was either shaken or sonicated to ensure complete mixing. The ternary phase extraction was expected to have relative percent recoveries similar to that of the Soxhlet method but require much less preparation time. After optimization, extractions had an average percent recovery of 117% for the sonicator trials, 126% for shaker trials, and 107% for Soxhlet. 1

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