Improvement in reproducibility of electrothermal vaporization/axially-viewed ICP-AES

In order to improve the reproducibility of a combined method of axiallyviewed ICP-AES and electrothermal vaporization, the application of an internal standard method was investigated. Profiles of emission intensities for various elements were compared. While the signal profiles for some elements such as Be and Co resembled each other, those for some elements such as Sn and Pd were different. In the case of the profiles with similar shapes, relative standard deviations (RSD) of emission intensities were reduced from more than 20 % to ca. 6 % by applying the internal standard method. In the case of the profiles with dissimilar shapes, however, the application of the internal standard method deteriorated the RSDs. When the intensity ratios of analyte and internal standard elements were within 2 to 5 times, the internal standard method was found to be most effective for the improvement in reproducibility