Sources of error in direct solid sampling Zeeman atomic absorption spectrometry analyses of biological samples with high water content

Abstract

Analytical errors were quantified in the direct analyses of trace elements in samples with high water content by means of solid sampling atomic absorption spectrometry with Zeeman effect background correction (direct SS-ZAAS). Time versus mass curves for HNO 3 (0.1 mol 1 −1), blood, kidney and liver at different temperatures (+20, +4, −20°C) and mass input (0.07 to 42 mg) were observed. Following a stabilization period, mass losses appeared to be nearly linear and independent of input mass. By means of a function using observed stabilization time and mass losses a 10% increase in analyte content was calculated as occurring at and below 0.06 mg. Experimentally, 10% increases were found to occur within a range 0–0.07 mg for weighed Cd solutions (0.1 and 0.2 ng mg −1 in 0.1 mol 1 −1 HNO 3 at 5°C). An automated solid sampling system consisting of microbalance, dispenser, transport system and electronics was integrated in the experiments. Manual working time and the necessity of operator presence were reduced by at least 80%. Performance and capacity compared well to the manual SS-ZAAS mode. Automated SS-ZAAS analysis in fresh animal tissues is proposed for use as a screening and reference method in official residue control.