Simultaneous determination of As, Cd, Cr and Pb in aqua regia digests of soils and sediments using electrothermal atomic absorption spectrometry and fast furnace programs

Abstract

A method was developed for the simultaneous multi-element determination of As, Cd, Cr and Pb in aqua regia digests of soils and sediments using an electrothermal atomic absorption spectrometer with a transversely heated graphite atomizer and longitudinal Zeeman-effect background correction. A fast furnace program with no pyrolysis stage or chemical modifier was used, and the total duration of the time-temperature program of the graphite furnace was 45 s. The method detection limits calculated from blank samples were 9.5 μg l −1, 0.18 μg l −1, 6.2 μg l −1 and 2.5 μg l −1 for As, Cd, Cr and Pb, respectively. Sample preparation procedures are briefly described. The accuracy of the method was confirmed with a certified reference soil (recoveries 90–110%, within-batch RSD most often less than 5% with six replicates) and with 12 sediment samples from an international proficiency test. z-scores were calculated for the results of the sediment samples with 46 satisfactory and only 2 questionable results. Some analytical problems that were encountered during analysis are described. Fast furnace programs were found to be suitable for the simultaneous determination of the four elements in aqua regia digests of soils and sediments.