A new alternative to liquid–liquid extraction for the speciation of organotin compounds is proposed using NaBEt4
ethylation–simultaneous solid phase microextraction (SPME)–GC-FPD. SPME is carried out using a
polydimethylsiloxane (PDMS) fibre immersed in 100 ml of solution for an adsorption time of 60 min. The
optimisation step confirms the importance of stirring the solution. The higher efficiency of mechanical stirring is
also clearly demonstrated. Under these conditions, SPME was applied for the first time to the simultaneous
extraction of butyl- and phenyltins and the analytical performances were evaluated. Very low detection limits were
reached, in the range 0.006–0.031 ng Sn l21
for butyltins and 0.2–0.6 ng Sn l21
for phenyltins. The repeatability
is also improved compared with classical liquid–liquid extraction thanks to the small volume of the fibre and the
on-line procedure (between 3 and 9% except for triphenyltin). The new method was applied to various
environmental samples such as natural aqueous samples, sediment and sewage sludge. The competitive extractions
between some organotins and organic matter present in complex matrices are discussed.