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Contoured Furnace Tube for Determination of Volatile Elements in ICP-Emission Spectrometry with Electrothermal Vaporization

Volume 39, Number 4 (Aug. 1985) Page 715-718

Matusiewicz, Henryk; Barnes, Ramon M.

For the semienclosed, nonstationary, graphite furnace atomizers used in atomic absorption or emission spectroscopy with most commercial instruments, the atomic absorption or emission signals recorded for volatile elements, such as bismuth, cadmium, gallium, indium, lead, and zinc, can appear as double peaks. Lead in particular tends to exhibit two peaks in AAS. With electrothermal vaporization into an inductively coupled plasma (ETV-ICP), we also observed an initial element peak followed by a second smaller peak. This phenomenon results from sample transfer in nonisothermal furnaces by condensation of the volatile element on the cooler outer ends of the furnace tube and the subsequent revaporation of the element as the ends of the tube are heated. The condensed metal is then removed in the final high-temperature clean-up cycle. This leads to poor reproducibility if peak-height measurements are used. Therefore, in this case peak-area measurements give better accuracy and precision than peak-height measurements. On the other hand, the AAS or AES determination of volatile elements is often difficult when graphite tubes of standard design with uniform wall thickness such as those used with conventional Massmann tube furnaces are employed.