Solid phase microextraction gas chromatography-glow discharge-optical emission detection for tin and lead speciation

Abstract

A modified interface between a gas chromatograph (GC) and a hollow cathode (HC) radiofrequency (rf) glow discharge (GD) with detection by optical emission spectrometry (OES) has been investigated for elemental speciation studies. Solid phase microextraction (SPME), used for extraction and preconcentration of organic compounds, is here used for the introduction of the metal species under investigation into the injector of the GC, after preconcentration of metal species ethylated “in situ” with sodium tetraethylborate. Tin [monobutyltin (MBT), dibutyltin (DBT) and tributyltin (TBT)] and lead species [trimethyllead (TML) and triethyllead (TEL)] were used as models and separated using a capillary column. Detection by rf-(HC)GD-OES was accomplished at 283.9 nm for tin and 283.3 nm for lead. After optimization of the parameters affecting the rf-(HC)GD signals (pressure, radiofrequency power and He flow rate used as plasma gas) and also the parameters affecting the SPME technique (adsorption time, desorption time, injector temperature and position of the fiber into the injector of the GC), the analytical characteristics were calculated. Good detection limits for the tin and lead species under study (0.021 µg L⁻¹ for MBT, 0.026 µg L⁻¹ for DBT, 0.075 µg L⁻¹ for TBT, 0.03 µg L⁻¹ for TEL and 0.15 µg L⁻¹ for TML) were achieved. Finally, the accuracy of the proposed speciation methodology was tested by analysing a certified reference material (sediment PACS-2) from the National Research Council of Canada.