Determination of absolute transport efficiencies of Be, Cd, In, Pb and Bi for electrothermal vaporization sample introduction into an inductively coupled plasma using an in-line electrostatic precipitator

A novel laboratory-constructed electrostatic precipitator for the determination of analyte transport efficiencies from a tube furnace electrothermal vaporization (ETV) sample introduction system is described. This simple experimental set up captures the analyte electrostatically using a negative corona discharge. The absolute transport efficiencies using experimental conditions typical of those applied to real analysis by ETV-ICP-MS were determined for Be, Cd, In, Pb and Bi to be 26 +/- 3, 39 +/- 8, 35 +/- 1, 50 +/- 11 and 35 +/- 1%, respectively. Pd and NaCl were evaluated as 'carriers' and were found to only marginally increase analyte transport for the elements investigated. Pd enhanced efficiencies 20-50% for all but Bi, which decreased by 17%. The NaCl produced transport enhancements of 10-50% for all five analytes. However, uncertainties in the measurements made several of the individual improvements statistically insignificant. The mean precipitator collection efficiency of the aerosol leaving the ETV for the five elements studied was found to be greater than 90% and was determined using the ICP-MS signal with the in-line precipitator's voltage either on or off. While 30 ETV firings were used for a single efficiency determination, reasonable precision could be obtained with approximately 10 firings while still employing reasonable analyte masses, i.e. approximately 20 ng. The transport results are in good agreement with previous studies using similar ETV design and analyte masses. (C) 2003 Elsevier Science B.V. All rights reserved.