Solid-phase extraction with injection of modified silica gel slurries into ETAAS for determination of Cu(II), Hg(II), Pd(II)

Electrothermal atomic absorption spectrometry with injections of slurry samples was used to determine Cu(II), Hg(II), and Pd(II) in natural and drinking waters after solid-phase extraction with modified silica gels. The formation regularities of the analytical signals of elements in the presence of excessive sorbent solid phase were studied. The solid phase of slurries under analysis (amorphous silicon dioxide with a particle size from 40 to 60 µm) favors the formation of a high (and sometimes uncorrected) background absorption. The conditions for the correct measurements of analytical signals of analytes elements: platform atomization, slurry concentration, peak height measurements, method for calibration curve plotting, and its linearity range, were determined. The preconcentration factor calculated as the weight ratio between analytes in a graphite furnace injected as a sorbent slurry after concentration and as a starting water sample (the injection volumes were identical) was 615. The limits of detection according to the 3σ concept were 1.5 ng/dm³ for Cu, 5 ng/dm³ for Pd, and 18 ng/dm³ for Hg. The developed method was applied with success upon determination of elements in real water samples using aqueous standard solutions and the ERM CA022a "Soft Drinking Water UK Metals"-certified reference samples of drinking water.