Headspace solid-phase micro-extraction and gas chromatography-ion trap tandem mass spectrometry method for butyltin analysis in sediments: Optimization and validation

In this work, headspace solid-phase micro-extraction (SPME) combined with gas chromatography-mass spectrometry (GC-MS) method for analysis of butyltin compounds in sediment samples was upgraded by the introduction of tandem mass spectrometry (MS/MS). Optimization and validation of this method based on an one step procedure, tetraethylborate in situ ethylation with simultaneous extraction by headspace SPME, combined with tandem mass spectrometry is described. A simple leaching/extraction step of mono-(M), di-(D) and tri-(T) butyltin (BT) compounds from the sediment is required as sample pre-treatment. The combination of the two techniques headspace SPME and MS/MS, led to very little matrix interference which permitted to attain limits of detection three or more orders of magnitude lower than those attained in previous methods: 0.3 pg g(-1) for MBT, 1 pg g(-1) for DBT and 0.4 pg g(-1) for TBT. Linear response range was from 0.02-1260 ng g(-1) for MBT, 0.07-1568 ng g(-1) for DBT and 0.04-2146 ng g(-1) for TBT and RSD < 15% was also obtained. The method was efficiently applied to a real sample sediment from Sado River estuary in Portugal, revealing the existence of BTs pollution, as the TBT level of 189 +/- 15 ng g(-1) was much higher than the maximum established as provisional ecotoxicological assessment criteria. (C) 2007 Elsevier B.V. All rights reserved.