Flow injection on-line solid phase extractive preconcentration of palladium(II) in dust and rock samples using exfoliated graphite packed microcolumns and determination by flame atomic absorption spectrometry

A sensitive and efficient flow injection preconcentration and matrix-separation technique using exfoliated graphite (EG) as column material was developed prior to flame atomic absorption spectrometry (FAAS) determination of palladium(II) in street/fan blade dust and rock samples. The method is based on the sorption of palladium(II)-diethylammonium dithiocarbamate chelate (which was found to be better among various thioligands) complex on to EG material and its subsequent elution with acidified methanol (0.01 M HCl in methanol). Using 8 ml of the sample, the detection limit achieved was 1.0 μg l−1. The accuracy of the method developed was checked by analysing certified reference material SARM-7. The precision obtained for five successive determination of 100 μg l−1 of palladium(II) was 2.4%. The performance of EG material was compared with allotropes of carbon in terms of pH, chelate concentration, weight of column material, sensitivity enhancement (w.r.t. conventional FAAS), detection limit, calibration range, selectivity and precision. Furthermore, performance of the EG material packed column was compared with commercially available C18 bonded silica gel/alumina columns for on-line FIA-FAAS determination of palladium(II).