Electrothermal Vaporization Introduction for ICP-MS

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This project under the direction of Chemistry Professor James A. Holcombe of the University of Texas, Austin, is supported by the Analytical and Surface Chemistry Program in the Division of Chemistry. The research concerns the introduction of solid samples and microsamples into the inductively coupled plasma-mass spectrometer (ICP-MS). Electrothermal vaporization (ETV) will be developed as the method of sample introduction. A set of fundamental studies will be done to provide an understanding of how material is transported to the ICP and the parameters influencing the process. Included in the work are studies of the influence of carrier particle size on the efficiency of analyte transport and the impact on transport of the nature of the type of association of analyte with carrier. A second aspect of the sample transportation investigations will be concerned with development of externally generated carriers. Two of the methods to be explored for this purpose are the pyrolysis of benzene to form carbon particles, and the reaction of gaseous titanium tetrachloride with water vapor to form titanium dioxide particles. An entirely different approach will involve the use of desolvated nebulizer-generated aerosols produced from aspiration of selected salts. Another method to generate carbon particles will involve oxygen ashing in the presence of palladium. Finally, to correct for space charge effects on analyte transport, automatic lens correction procedures will be explored to provide a dynamic correction technique for the transient signal produced by ETV-ICP-MS. Instruments for chemical analysis necessarily must have a means of introducing the sample to be analyzed into the instrument. In some cases, this requires a change in the physical state of the species of interest, for example, from a liquid to a gas. Often, not all of the sample enters the measurement zone of the instrument and therefore the efficiency of transport of sample is of great interest. This project is concerned with this problem as it is encountered with the inductively coupled plasma-mass spectrometer.