ABSTRACT

I. INTRODUCTION Solid phase microextraction (SPME) was developed to address the need to facilitate rapid sample preparation both in the laboratory and on-site where the investigated system is located [1]. In the technique a small amount of extracting phase dispersed on a solid support is exposed to the sample for a well-defined period of time. In one approach a partitioning equilibrium between the sample matrix and extraction phase is reached. In this case convection conditions do not affect the amount extracted. In a second approach utilizing short-time preequilibrium extraction, if convection/agitation are constant, then the amount of analyte extracted is related to time. Quantification can then be performed based on timed accumulation of analytes in the coating. Figure 1 illustrates several implementations of SPME that have been considered. They include mainly open bed extraction concepts such as coated fibers, vessels, and agitation mechanism disks, but in-tube approaches are also considered. Some best address issues associated with agitation, and others ease of implementing sample introduction to the analytical instrument. It should be noted that solid phase microextraction was originally named after the first experiment using an SPME device, which involved extraction on solid fused silica fibers, and later, as such, as a reference to the appearance of the extracting phase, relative to a liquid or gaseous donor phase, even though it is recognized that the extraction phase is not always technically a solid.