Abstract

A new spray chamber, termed a flushing spray chamber (FSC), has been developed for inductively coupled plasma mass spectrometry aimed at more rapid and reliable multi-element analyses of solution samples. The sample solutions are nebulised by a conventional concentric nebuliser and then directly aspirated into the glass chamber. A continuous flushing system within the glass chamber prevents long residence times of trapped sample droplets. The glass chamber used has single flow path configuration with smaller internal volume (about 50 mL) that avoids the stagnation of the sample aerosol inside the spray chamber. The combination of continuous washing and small stagnation times of the mist results in shorter washout time. Typical washout time for 1 µg g⁻¹ concentrations of U and Hg are about 40 s and 200 s, respectively, and these are about 1/4 and 1/100 of the level of the typical washout time observed with a conventional spray chamber including the Scott-type spray chamber. In the case of Os, because of a serious memory effect, the washout time for 1 µg g⁻¹ concentration of OsO₄ solution could not be defined. Nevertheless, the washout time from 1 ng g⁻¹ concentration of OsO₄ solution could be remarkably reduced, to 150 s, and this is almost two orders of magnitude shorter than the washout time achieved by the conventional spray chamber. When chilled water (about 4 °C) is used within the flushing system, stability, sensitivity and oxide level show no significant differences between the normal and modified nebuliser system. The data presented here demonstrate clearly that the practical measurement time can be shortened by means of the FSC developed in this study.