A quantitative extraction method for the determination of trace amounts of both butyl- and phenyltin compounds in sediments by gas chromatography-inductively coupled plasma mass spectrometry

Abstract

A simple and reliable extraction method was developed for quantitative determination of both butyl- and phenyltin compounds in sediments by capillary gas chromatography combined with inductively coupled plasma mass spectrometry (GC-ICP-MS). Both types of organotin compounds were extracted quantitatively from sediment by mechanical shaking into tropolone-toluene and HCl-methanol. After phase separation and pH adjustment, these organotins were ethylated with sodium tetraethylborate. The method was evaluated by analyzing PACS-2 and NIES No. 12 sediment certified reference materials. The dibutyltin (DBT; 1.14 +/- 0.02 micrograms g-1) and tributyltin (TBT; 1.01 +/- 0.04 micrograms g-1) values observed in PACS-2 sediment closely matched the certified values (DBT, 1.09 +/- 0.15; TBT, 0.98 +/- 0.13 microgram g-1 as tin). The monobutyltin (MBT) value was higher (0.62 +/- 0.02 microgram g-1) by more than two fold over the reference value (0.3 microgram g-1 as tin). The concentrations of TBT (0.18 +/- 0.04 microgram g-1) and triphenyltin (TPhT; 0.0099 +/- 0.002 microgram g-1) in the NIES No. 12 sediment were also in good agreement with the certified and reference values of TBT (0.19 +/- 0.03 microgram g-1 as compound) and TPhT (0.008 microgram g-1 as compound), respectively. Recoveries of TBT, tripentyltin (TPeT) and TPhT from spiked sediments were satisfactory (TBT, 102 +/- 3.4%; TPrT, 96 +/- 3.4%; TPhT, 99 +/- 8.5%). The detection limits as tin were in the range 0.23-0.48 ng g-1 for a 0.5 g sample size. It is also noteworthy that clean-up of the extract is not necessary because of the superior selectivity of ICP-MS detection. The present method was successfully applied to marine sediment samples.