Studies of Analyte Particle Transport in a Particle Beam-Hollow Cathode Atomic Emission Spectrometry System

Abstract

The particle beam–hollow cathode glow discharge atomic emission spectrometry system appears to be a viable analytical method for volume-limited liquid samples. Systematic enhancements and reductions in instrumental response were related to the analyte transport efficiency through the particle beam interface. The effects of liquid flow rate and analyte input concentration on analyte transport efficiency were evaluated in an attempt to explain these effects on the analytical signal. Two specifically designed collectors were mounted within the glow discharge source for sampling analyte particles passed through the particle beam interface. Atomic absorption spectrometry and scanning electron microscopy were applied to determine analyte transport efficiencies and particle size distributions, respectively. In general, transport efficiencies of 4–18% were achieved. Improvements in analyte response, noted in previous studies, on addition to the sample of concentrated HCl (1+5, v/v) can now be attributed to enhanced analyte transport through the particle beam interface by virtue of an increase in the size of the desolvated analyte particles. The size distribution of analyte particles appears to change with the distance from the center to the edge area of the sample collector as most particles follow a straight pathway to the hollow cathode, with very little evidence of dispersion. Typical particle sizes lie in the range 2–8 µm.