Direct determination of Cd in seawater by graphite furnace-atomic absorbance spectrometry with Zeeman-effect background correction

This article describes an accurate method for direct determination of cadmium in seawater using an end-heated atomizer graphite furnace atomic absorbance spectrometry. To avoid interferences caused by matrix elements, ammonium nitrate and di-ammonium hydrogen phosphate were added as matrix modifiers to the sample before analysis. Experiments showed that best Cd signal was obtained fot a sample volume of 15 μl with the addition of 13 μl of NH_4NO_3, (16%) and 3μl of (NH_4)_2HP0_4 (4%), an ashing temperature of 400-550℃ and an atomization temperature fixed at 1200℃. Detection limit(3σ from ten blank replicas) was 0.013 ppb and determination limit (10σ from ten blank replicas) was 0.044 ppb.publishe