Hollow cathode lamp-excited ICP atomic fluorescence spectrometry—an update

Abstract

Recent instrumental and sample handling developments in hollow cathode lamp-excited ICP atomic fluorescence spectroscopy (HCL-ICP-AFS) to improve detection limits, to extend capabilities to organic solvents, and to determine sulfur and phosphorus in the vacuum u.v. are presented. The introduction of a small amount of a carbon-containing gas, such as propane, to the sample introduction system prevents re-formation of oxides by the refractory elements in the plasma observation zone and is necessary for their determination in aqueous samples. With organic samples the intense radiation resulting from incomplete combustion of the organic solvent in the plasma observaton zone can degrade detection limits or saturate the photodetector, unless a small amount of oxygen is introduced into the sample introduction system and a dioxane-organic solvent mixture is employed. An ICP torch with a central tube fitted with a bored, replaceable graphite rod promotes reduction of refractory metal oxides to free metals and reduces the compromise in rf power required for the simultaneous analysis of refractory and nonrefractory elements. An ICP torch with a straight, extended outer tube is shown to be freer of solute vaporization interferences than a conventional ICP-AES torch and to be less susceptible to noise from pneumatic resonances than a torch with an extended outer tube with a neck at the top.