DEVELOPMENT OF A SUPERCRITICAL-FLUID EXTRACTION PROCEDURE FOR TRIBUTYLTIN DETERMINATION IN SEDIMENTS

The effect of extraction variables, such as extraction time, temperatu re and extraction agent composition (X), in supercritical fluid extrac tion (SFE) of tributyltin (TBT) from a spiked sediment, has been optim ized by using a factorial-fractional experimental design. Under the op timum conditions (T = 60 degrees C, P = 35 MPa, X = 5.1 M methanol in CO2, t = 30 min) the TBT extraction efficiency was 82% with a coeffici ent of variation (C.V.) of 9.2% (n = 5). Furthermore, the analytical p rocedure was validated using a reference material (RM) certified for i ts TBT content and was successfully applied to the analysis of a Certi fied Reference Material (CRM). Furthermore, an intercomparison of the SFE with another extraction procedure based on atmospheric pressure li quid extraction (APE) for the TBT determination in sediments has been carried out. Although TBT recoveries were significantly higher in the SFE procedure, the precision of both methods was comparable, probably associated to the similar steps in the extract treatment procedure (de rivatization and clean up).