Sampling and determination of metal hydrides by solid phase microextraction thermal desorption inductively coupled plasma mass spectrometry

Direct coupling of solid phase microextraction (SPME) with inductively coupled plasma mass spectrometry (ICP-MS) was used for the non-selective determination of arsenic, selenium, antimony and tin species amenable to hydride generation. A thermal desorption interface consisting of a heated glass-lined splitless type GC injector was placed directly at the base of the torch to minimize the length of the transfer-line. The effects of time and concentrations of sodium borohydride and hydrochloric acid on the extraction efficiency were optimized. Polydimethylsiloxane (PDMS) and polydimethylsiloxane/Carboxen (PDMS/Carboxen) SPME coatings were compared for the headspace extraction of the hydrides. PDMS/Carboxen showed better extraction capacity and enhanced selectivity for tin hydrides. SPME provided good sensitivity and an approximately 3.5 decade linear response range. Detection limits for As, Se, Sn and Sb using a PDMS/Carboxen fiber were 70, 5300, 8 and 310 pg mL(-1), respectively. Method validation using NRCC SLRS-4 (Riverine Water) and CASS-4 (Nearshore Seawater) reference materials showed good agreement between certified and measured values for total arsenic.