Author(s): Federica Bianchi, Maria Careri, Monica Maffini, Alessandro Mangia, Claudio Mucchino
The quality assessment of water in term of organometallic compounds is one of the key tasks of modern environmental analytical chemistry. For this purpose a rapid and very sensitive method based on solid-phase microextraction (SPME) followed by gas chromatography-inductively coupled plasma-mass spectrometry (GC-ICP-MS) was developed and validated aimed at the determination of dimethyl-, dibutyl- and tributyltin in water samples. A divinylbenzene/ carboxen/polidimethylsiloxane fiber was used for the SPME sample treatment. Coupling of the ICP-MS with GC was accomplished developing an easy-to-fit in-house interface. In general optimal conditions were found by using the enhanced “hot plasma/protective ion extraction” introduction system. Validation was carried out in terms of limit of detection, limit of quantitation, linearity, precision and trueness. GC-ICPMS made possible the detection of the organotin compounds at ultratrace levels, quantitation limits ranging from 0.04 to 5 ng l-1. Linearity was established over two orders of magnitude for all the investigated compounds. Good precision was obtained both in terms of intra-day repeatability and between-day precision on two concentration levels (RSD lower than 15%). Recovery values ranging from 75±2% to 99±1.2% (n = 3) were calculated. The method was proved rapid, GC-ICPMS allowing for the separation of organotin species in less than 7 minutes. The method was used in routine analysis of environmental samples (fresh and marine water samples).