Evaluation of syringe-connected minicolumn technique for preconcentration of some trace elements using chromosorb-103 and determination by flame atomic absorption spectrometry

A syringe-connected minicolumn (SCM) technique has been developed for preconcentration and enrichment of cobalt, iron, and lead in river-water samples prior to their determination by flame atomic absorption spectrometry (FAAS). The proposed technique is substituted for the classical batch and column techniques all of which are off-line methods. The method proposed was compared with the column technique with respect to easiness, rapidness, simplicity and some analytic performances such as recovery, precision, accuracy and risk of contamination. The minicolumn was filled with Chromosorb-103 as a sorbent. In order to retain the analyte elements, the sample solution was drawn into the syringe and discharged back passing through the sorbent in the minicolumn. The analyte elements were quantitatively retained at pH greater than or equal to4 if they were complexed with ammonium pyrrolidine dithiocarbamate (APDC) prior to passing through to the sorbent. The analytes sorbed on the minicolumn was then eluted with 1.0 mol L-1 HNO3 in acetone again drawing and discharging the eluent. Optimum flow rates of sample or eluent for sorption and elution procedure were 20 mL min(-1) for both drawing and discharging cases. The proposed technique was successfully applied to the determination of analytes in certified reference material and spiked river-water samples. The recoveries of analytes from certified reference material (Bovine liver) and river-water samples were quantitative and reproducible (>96%, with relative standard deviation (RSD) of 1-5%). The developed technique is simple, fast, and accurate. Detection limits (3sigma) were 4.8 mug L-1 for Co, 14 mug L-1 for Fe, and 15 mug L-1 for Pb. Very high preconcentration factors up to 200-fold could be achieved.