Epsilon Open Archive

Abstract

This thesis deals with the use of supercritical fluid extraction (SFE) in environmental analysis. Traditionally SFE in environmental analysis has been used for quantitative extraction. In this thesis, quantitative extraction as well as other applications of SFE will be discussed.

Studies of SFE extraction efficiency of pesticides from water and soil matrices were performed. Solid phase extraction (SPE) with Empore discs and bulk sorbent in combination with SFE, showed promising results for extraction of pesticides from water samples. With the bulk sorbent, it may also be possible to design effective extraction procedures for specific target analytes, using sorbents with different chemical properties. Sulfonylurea herbicides were extracted from soil with the objective to develop a general SFE procedure for sulfonylureas. The results showed that optimized SFE methods cannot always be directly applied to similar compounds without further method development.

The possibility to fine tune the selectivity of SFE were used for pesticide retention
studies on model matrices and soils. Investigation on model matrices with well known properties (sand and silica) gave valuable information for further studies on binding mechanisms. The purpose of such studies would be to characterize different interactions that determine the behaviour of pesticides in complex matrices such as soils. Extraction of soils under moderate SFE condition, i.e. nonquantitative extraction, allows the interaction between soil and analyte to influence the recovery. This is useful for pesticide retention studies. The results indicate that nonquantitative extraction can be used to study the relative strength of different types of sorptive sites. The use of SFE to determine pesticide sorption coefficients (~) in field-moist soil has the potential to yield better information to model the fate of pesticides in the field than sorption coefficients characterized by traditional batch-slurry techniques.