Palladium nitrate-magnesium nitrate modifier for graphite furnace atomic absorption spectrometry. Part 2. Determination of arsenic, cadmium, copper, manganese, lead, antimony, selenium and thallium in water

Abstract

If the palladium nitrate-magnesium nitrate modifier is applied to the analysis of water, a common set of conditions for the determination of As, Cu, Mn, Pb, Sb and Se can be used. For Cd and Tl lower pyrolysis and atomisation temperatures are required. Twenty-one possible interferents were investigated at maximum concentrations between 1 and 500 mg l^–1 and only two were found to have an effect greater than ±10%. The determination of Tl was affected by sodium chloride at concentrations above 100 mg l^–1, hence the addition of Li is recommended to control this interference. Five mg l^–1 of Fe decreased the Se signal by about 15% when deuterium-arc background correction was used but had no influence in an instrument with Zeeman-effect background correction. For an instrument with continuum source background correction it was also necessary to determine Cu using the secondary resonance line at 327.4 nm because of spectral interference due to Pd at the primary resonance line. Precision was about 1% in the optimum working range and between 2 and 5% at 0.05 A s. Detection limits (2.33 σ) were 1.2 µg l^–1 for As, 0.02 µg l^–1 for Cd, 0.3 µg l^–1 for Cu, 0.45 µg l^–1 for Mn and Pb, 1.2 µg l^–1 for Sb, 0.6 µg l^–1 for Se and 0.8 µg l^–1 for Tl.