Matrix modification by Cu(NO3)(2) for the determination of gold by electrothermal atomic absorption spectrometry with a molybdenum tube atomizer

Matrix modification by copper nitrate in electrothermal atomic absorption spectrometry (ETAAS) of gold with a molybdenum tube atomizer has been investigated. The addition of copper nitrate served to eliminate the interferences from 10(4)-10(5)-fold concentrations of foreign elements at the 890 degrees C pyrolysis temperature. The absolute characteristic mass (giving 0.0044 absorbance) of gold in the presence of copper nitrate with the Mo atomizer was 0.26 pg and the detection limit was 38 pg/ml. These values were several times better than those obtained with graphite atomizers. The recovery of spiked gold in biological materials was in the range 96-106%. A sensitive and accurate ETAAS method was developed for complex matrix samples.