Solid Phase Microextraction for Trace Element Determination: The Fiber and Its Evolution

Abstract

Trace element determination and speciation at the part-per-trillion level (ng L−1) are challenging for most elemental detectors and become harder when complex samples are analyzed. Solid phase microextraction (SPME) can provide matrix separation along with analyte preconcentration which are essential steps to obtain interference free and measurable signals for quantitation of inorganics at these low levels. Fiber SPME was introduced first and it is still an indispensable tool for Hg and Sn speciation, and for the analysis of volatile organometallic metabolites. In recent years, several other SPME approaches have been employed for inorganic analysis, including in-tube SPME, capillary microextraction, hollow fiber SPME, micropipette tip SPME, SPME on a stir bar, SPME on a microfluidic device and dispersive SPME. A significant advancement in coatings has closely followed the developments of novel SPME formats: at this time a number of nanocomposites and polymers were available enabling the microextraction of most transition metal ions, directly in solution, without the need for derivatization.