On-line separation and preconcentration of cadmium, lead and nickel in a fullerene (C60) minicolumn coupled to flow injection tungsten coil atomic absorption spectrometry Original Research Article

A flow system was coupled to a tungsten coil electrothermal atomizer (150 W) for on-line separation and preconcentration of cadmium, lead and nickel based on the formation of DDC complexes and sorption into a minicolumn packed with fullerene C60. Three way solenoid valves used for sample and reagents management as well as the tungsten coil power supply were controlled by a computer running a programme written in Visual Basic, which was employed in synchronism with the original software of the atomic absorption spectrometer. The fullerene column (5 mm length, 2 mm i.d.) was inserted into the tip of the autosampler arm, and elution was performed by sampling 35 μl of methanol from the autosampler cup. With 3.0 ml of sample (loading time of 60 s) enrichment factors ranging from 100 to 150 were achieved. The detection limits for cadmium, lead and nickel were 2.2, 23 and 75 ng l−1, respectively. No interference effects were observed on cadmium, lead and nickel preconcentration in the presence of up to 106 fold concentrations of sodium, potassium, calcium or magnesium. Application of t-test to the results obtained by the proposed method and the certified values of cadmium, lead and nickel in five water reference materials did not reveal significant differences at the 5% probability level.