Abstract

The methods used by laboratories participating in FAPAS^® proficiency testing covering trace metals have been reviewed. Techniques that tend to give the highest percentage of satisfactory z-scores are identified. Comparisons are made of digestion and extraction techniques, use of atomic absorption spectrophotometry (AA: graphite furnace and flame) and inductively coupled plasma techniques (ICP-OES and ICP-MS). It does not follow that one technique is more accurate than the others, because some individual laboratories consistently achieve satisfactory results using any of the five main digestion techniques and any of the major detection techniques. The results do, however, give an indication of which techniques are easier to perform correctly and with a high standard of accuracy. There are also other factors that may influence results such as instrument set-up, background correction and data analysis.