Utilization of metallic platforms in electrothermal vaporization inductively coupled plasma mass spectrometry

Abstract

A method to improve the analytical performance of hydride trapping on Pd inside a graphite furnace and subsequent determination by ICP-MS was investigated. Strips of tungsten, tantalum, molybdenum and rhenium were coated (electroplated/sputtered) with palladium and used as platforms inside the graphite furnace. A typical pyrolytic graphite-coated graphite platform was also coated with Pd in the same manner, for performance comparisons. Scanning electron microscopy (SEM) and X-ray fluorescence spectrometry were used to characterize the surfaces. SEM showed a smoother Pd layer covering the metallic substrates when compared with the graphite. An analyte signal reproducibility study revealed that Ta, Re and Mo were not ideal substrates for this purpose. The As peaks obtained from trapping on the graphite platform were broadened with a decrease in intensity after a few firings. The Pd-sputtered tungsten platform showed superior performance over the other platforms. The linear dynamic range obtained using this platform was improved by one order of magnitude in the upper limit (from 1 to 100 ng ml^–1) over that reported using a graphite platform in previous work. The limit of detection of arsenic was found to be 0.01 ng ml^–1, within the same range obtained from the graphite platform.