Effects of complexing agents and acid modifiers on the supercritical fluid extraction of native phenyl- and butyl-tins from sediment

Abstract

The effects of: (1) the modifier type (methanol and formic, acetic and propionic acids), (2) complexing agents (diethylammonium diethyldithiocarbamate, ammonium pyrrolidinedithiocarbamate) either with or without acidic modifiers, (3) the extraction temperature (50–80 °C) and pressure (30–50 MPa), (4) the extraction procedure (static–dynamic or dynamic), and (5) the volume of static modifier, on the extraction efficiency of native butyl- and phenyl-tin compounds from sediment, were evaluated comprehensively. The highest extraction efficiency for butyl- and phenyl-tin compounds was obtained at 30 MPa and 50 °C by using CO2 modified with acetic acid (200 μl in the cell). Supercritical fluid extraction (SFE) extracts were hexylated and determined by GC–FPD using a 610 nm bandpass filter without any clean-up step. In summary, the developed analytical procedure is robust (no restrictor clogging; free from FPD interferences), it is low-cost (no complexing agents needed), it has a high sample throughput (<3 h), it is independent of the matrix for the determination of butyltin compounds in sediment, and it provides the highest precision among the SFE procedures reported for organotin determination. © 1998 John Wiley & Sons, Ltd.