Determination of copper by flame atomic absorption spectrometry using discrete nebulisation of a carbon tetrachloride extract

Copper extracted into carbon tetrachloride as a dithizonate was determined by flame atomic absorption spectrometry with discrete nebulisation and without deuterium background correction. Injection of the organic extract gave an interesting signal profile, owing to the decrease in the flame temperature. Injection volumes of 35–45 µl of the organic extract gave the highest, most constant and reproducible signals. For the same copper concentration, the signal intensity obtained by injecting 40 µl of the extract was about 1.6 times larger than that obtained both by continuous nebulisation of the extract and by injection of 100 µl of aqueous solution. The detection limit obtained by injecting 40 µl of the extract was 49 p.p.b. or 2.0 ng [signal to noise ratio (S/N)= 2]. The method was successfully applied to the determination of copper in a certified reference material from the National Institute for Environmental Studies (NIES-CRM No. 9, Sargasso), and the results agreed well with the certified value.