Analytical features of SPME

This section deals with the basic analytical properties enhanced by the use of SPME (viz. selectivity and sensitivity), in addition to other major analytical properties including accuracy and precision. 

The amount of analytes that is extracted by SPME depends mainly on the nature of the coating, its volume, whether and how the target analytes are derivatized and the matrix modified, and whether the sample is heated or the coating cooled. 

As noted earlier for the extraction of BTX compounds and shown in Fig. 4.28, coating/sample partition coefficients depend largely on the type of coating for a given analyte. Derivatization and temperature also have some influenee on selectivity and must be adjusted as a funetion of the analytes, matrix and state of the sample. 

Solid sample treatments involving the removal of volatile species 

Because SPME is a single-step technique — which minimizes sources of random errors associated with transfer of the analytes — it exhibits very good precision with clean, model samples. In fact, the precision of SPME is typically in the region of 5% (as RSD) with manual operation and can be as low as 1% with model samples processed using an auto-sampler. On the other hand, complex matrices and carry-over effects can result in RSD values as high as 92% [226,227], 

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