Flame Atomic Absorption Spectrometric Determination of Cadmium, Cobalt, and Nickel in Biological Samples Using a Flow Injection System with On-Line Preconcentration by Co-precipitation without Filtration
Cadmium, cobalt, and nickel at ng/g to μg/g levels in plant and animal tissue reference materials and at μg/L levels in blood and urine were determined by flame atomic absorption spectrometry. The analyte elements were preconcentrated and separated from the bulk of the matrix
by on-line co-precipitation with the hexamethylene ammonium hexamethylene dithiocarbamate iron(II) chelate complex in a flow injection system. The precipitate was collected in a knotted reactor made from 150-cm-long, 0.5-mm-i.d. Microline tubing without using a filter. The precipitate was
dissolved in methyl isobutyl ketone and introduced directly into the nebulizer-burner system of an atomic absorption spectrometer. Ascorbic acid in an HC1/KC1 buffer was added on-line in order to reduce iron(III) to iron(II) because of its much better efficiency as a collector for trace elements.
Reagent concentrations were optimized so that at least 200 mg/L of iron and 15 mg/L of copper could be tolerated in the sample solution without causing significant interferences. The portion of the analyte retained in the collector was about 70% for cadmium and 50% for cobalt and nickel. Enrichment
factors of 24, 19, and 20 were obtained for cadmium, cobalt, and nickel, respectively, with the use of a 40-s co-precipitation time, resulting in enhancement factors, including the effect of the organic solvent, of 52, 43, and 52, respectively. The detection limits (3σ) for cadmium,
cobalt and nickel were 0.15, 1.3, and 1.5 μg/L, respectively, and the precision was 1.5% RSD for 10 μg/L, Cd, 2.7% RSD for 50 μg/L Co, and 1.8% RSD for 50 μg/L Ni. The analytical results obtained for a number of standard reference materials and control samples were in good agreement
with the certified or recommended values.
Cadmium, cobalt, and nickel in biological materials;
Flame atomic absorption spectrometry;
Flow injection on-line co-precipitation
Document Type: Research Article
Department of Applied Research, Bodenseewerk Perkin-Elmer GmbH, D-7770 Überlingen, Germany
Department of Applied Research, Bodenseewerk Perkin-Elmer GmbH, D-7770 Überlingen, Germany; on leave from the Flow Injection Analysis Research Center, Institute of Applied Ecology, Academia Sinica, Shenyang, 110015, China
Publication date: November 1, 1991
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