Solid sampling in the determination of precious metals at ultratrace levels

The determination of platinum group metals in solid samples at ultratrace levels is demanded in many situations. This complicated analytical task traditionally requires a complex, time-consuming analytical procedure if sample digestion is intended. This article discusses recent advances in several analytical techniques (spark-optical emission spectrometry, graphite furnace-atomic absorption spectrometry, electrothermal vaporization-inductively coupled plasma-mass spectrometry (ICP-MS), laser ablation-ICP-MS and glow discharge-MS) that can provide quantitative results by direct analysis of the solid samples. They increase both the sample throughput and the sensitivity while diminishing contamination issues, and enable the determination of these elements at levels below 10 mu g/g. Obviously, these solid-sampling techniques result in a higher risk of matrix effects and spectral overlap. In order to compare the strengths and weaknesses of the different techniques evaluated, we will discuss different strategies to cope with these problems, such as the separate vaporization of the analytes and the interfering species in time or the use of chemical or mass resolution. (C) 2007 Elsevier Ltd. All rights reserved.