Solid phase extraction is the very popular technique currently available for rapid and selective sample prepara- tion. The versatility of SPE allows use of this technique for many purposes, such as purification, trace enrichment, desalting, derivatisation and class fractionation. The last few years have been chracterized by a wide interest in this technique and many publications describing SPE methods have been published [1]. This period is connected with theintensive development of research procedures for novel types of sorptive materials and lasted from the late 1960s until the beginning of the 1980s. The introduction of a wide spectrum of sorptive materials into analytical pro- cedures gave a new stimulus for the development of SPE methodology [2].
The principle of SPE is similar to that of liquid-liquid extraction (LLE), involving a partitioning of solutes be- tween two phases. However, instead of two immiscible liquid phases, as in LLE, SPE involves partitioning be- tween a liquid (sample matrix or solvent with analytes) and a solid (sorbent) phase. This sample treatment tech-