Custom-made interface between electrothermal vaporiser and inductively coupled plasma-mass spectrometer: determination of nickel by isotope dilution in plant samples

ICP-mass spectrometer Perkin Elmer Elan 6000 was adapted for ETV analysis by coupling with GBC GF 3000 graphite furnace atomiser. Both instruments were connected by a 25 cm long PTFE tubing of 6 mm i.d. and a custom-made interface. The apparatus was applied to nickel determination using isotope dilution technique. The efficiency of analyte transfer through the interface was approximately 20%, however the incomplete transfer did not influence the blank values. Measured isotope ratio was very stable, whereas the magnitude of ion signal showed a little shift. CRM samples were analysed after microwave decomposition and by slurry technique as well. Obtained results were compared with those of pneumatic sample nebulisation after nickel separation on Chelex column. All tested techniques gave accurate results with comparable precision. However, the slurry technique allowed significant decreasing of the blank values and the limit of detection. The duration of analysis run can also be substantially shortened from several hours to a few minutes.