An Attempt to Improve the Measurement Precision in Tungsten-Filament Electrothermal Vaporization / ICP-Mass Spectrometry for the Determination of Trace Phosphor

In order to improve the measurement precision in tungsten-filament electrothermal vaporization (WF-ETV) / inductively coupled plasma mass spectrometry (ICP-MS) for the determination of trace phosphor, we attempted the application of an internal standard method. The delay time between the discharge of a capacitor in the WF-ETV system and the start of measurement in ICP-MS was optimized for the simultaneous measurement of several elements. Operating parameters for WF-ETV were investigated to obtain appropriate intensities of phosphor, and consequently the optimum values of electric current for desolvation and sample volume became 3.3 A and 3.0 L, respectively. While relative standard deviation (RSD) of intensities of phosphor more than 50% was improved to 17% by correcting with those of cobalt as an internal standard element, the improved RSD was almost the same as the value obtained before. It was found that more detailed studies for selecting suitable internal standard elements were needed to improve the reproducibility of WF-ETV / ICP-MS