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was less than 1 g/l then it was shown that very low recoveries were likely. Nevertheless, for the more
volatile contaminants, the technique gave results that were sufficiently accurate for many environmental
analyses.
Boyd-Boland et al. [24] developed a solid phase micro extraction procedure for measuring 60 different
pesticides in water, using a small-diameter optical fiber that had been coated with a polymeric
stationary phase. The fiber is housed in a syringe assembly and the fiber exposed to the water sample
inside the syringe for about 15 minutes. After the water contaminant have been absorbed into the fiber
coating, the fiber is removed and placed in the injection system of the gas chromatograph. The fiber is
then heated and the materials desorbed and passed onto the GC column.
Figure 5.22
Total Ion Current Chromatogram Showing the
Simultaneous Determination of 60 Pesticides (ref.24).
Two types of polymer coating were used, polydimethylsiloxane (100 µm thick) and polyacrylate (95
µm thick). The fibers were prepared in accordance with the manufacturers instructions which amounted
to heating
