SOURCES OF ERROR IN DIRECT SOLID SAMPLING ZEEMAN ATOMIC-ABSORPTION SPECTROMETRY ANALYSES OF BIOLOGICAL SAMPLES WITH HIGH WATER-CONTENT

Analytical errors were quantified in the direct analyses of trace elem ents in samples with high water content by means of solid sampling ato mic absorption spectrometry with Zeeman effect background correction ( direct SS-ZAAS). Time versus mass curves for HNO3 (0.1 mol l(-1)), blo od, kidney and liver at different temperatures (+20, +4, -20 degrees C ) and mass input (0.07 to 42 mg) were observed. Following a stabilizat ion period, mass losses appeared to be nearly linear and independent o f input mass. By means of a function using observed stabilization time and mass losses a 10% increase in analyte content was calculated as o ccurring at and below 0.06 mg. Experimentally, 10% increases were foun d 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) HNO3 at 5 degrees C). An automated soli d sampling system consisting of microbalance, dispenser, transport sys tem and electronics was integrated in the experiments. Manual working time and the necessity of operator presence were reduced by at least 8 0%. Performance and capacity compared well to the manual SS-ZAAS mode. Automated SS-ZAAS analysis in fresh animal tissues is proposed for us e as a screening and reference method in official residue control.