Evaluation of microwave heating digestion and graphite furnace atomic absorption spectrometry with continuum source background correction for the determination of iron, copper and cadmium in brine shrimp

Abstract

Iron, copper and cadmium are determined in brine shrimp specimens using graphite furnace atomic absorption spectrometry. Four different digestion procedures, (i.e., dry ashing, hot-block, high pressure and microwave heating digestion) are compared. It was concluded that microwave heating digestion in polyethylene autosampler cups is excellent for the rapid dissolution of sub-milligram amounts of biological material. Applying platform atomisation and peak-area integration, a calibration against acid standards can be used for the determination of the three metals. The use of the ammonium phosphate-magnesium nitrate sample modification for the determination of cadmium allows a maximum pre-treatment temperature of 1000 °C. Continuum source background correction does not cause correction errors and background-corrected analyte absorbance signals appear undistorted. There is good agreement between the results obtained from furnaces and flames, confirming that the chemical and spectral interferences have been overcome.