Fractionation of Cd and Pb in BCR No. 601 sediment reference material following the BCR protocol for sequential extraction and determination by electrothermal atomic absorption spectrometry using permanent modifiers

Abstract

Fractionation of Cd and Pb was determined in the BCR (Community Bureau of Reference of the Commission of the European Communities) sediment reference material No. 601, which is certified for metals sequentially extracted according to the BCR protocol. The determination was carried out by electrothermal atomic absorption spectrometry, using palladium nitrate and magnesium nitrate modifier in solution and the analyte addition technique, as recommended in the BCR protocol. In addition, the standard calibration technique and the use of Ru and Ir–Rh as permanent modifiers were investigated in order to simplify and speed up the procedure significantly. Although some of the results were not within the 95% confidence level of the certified values, there was no significant difference between the results using the two calibration approaches and the three modifiers when a t-test was applied for a confidence level of 99%. The limits of detection obtained in the three extracts and the three modifiers were of the same order of magnitude, in the range 12–80 ng g⁻¹ for Cd and in the range 1.2–14 ng g⁻¹ for Pb. The precision was reasonable, with relative standard deviations from 2 to 28% for all studied conditions. The standard calibration technique and the use of a permanent modifier are recommended since these conditions significantly reduce the total analysis time and reduce blank levels due to modifier contamination.