Analytical Sciences

Double-Viewing-Position Single-Particle Inductively Coupled Plasma–Atomic Emission Spectrometry for the Selection of ICP Sampling Position in SP-ICP Measurements

Ka-Him CHUN, Hua ZHANG, and Wing-Tat CHAN

Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, PR China

Double-viewing-position single-particle inductively coupled plasma–atomic emission spectrometry (DVP-SP-ICP-AES) measures emission intensity at two ICP vertical positions simultaneously using a single photomultiplier tube. A particle travelling up the ICP gives two consecutive temporal emission peaks. The Yb II 328.937-nm emission intensity of the two peaks for single Yb₂O₃ particles of diameter of 200 – 2000 nm are plotted against each other in a correlation plot. The correlation is poor when the gas temperature at the lower observation position is approximately the boiling point of the particles. Poor particle vaporization at the center of the central channel occurs because the gas temperature is 400 K lower than the temperature at the rim. The correlation is improved by shifting the observation positions up or using helium–argon mixed carrier gas to increase the gas temperature. Gas temperature is an important parameter for precise single particle-ICP measurements. DVP-SP-ICP-AES can be used to identify poor particle vaporization without the need of temperature measurement.

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