Synthetic zeolites as sorbent material for on-line preconcentration of copper traces and its determination using flame atomic absorption spectrometry

This work assesses for the first time the potential of synthetic zeolites as adsorptive material for the preconcentration of copper traces. This involves the formation of a copper chelate, its adsorption on sodium lynde Type A (Na-LTA) and sodium faujasite Type X (Na-Fau) synthetic zeolite minicolumns, and its elution with 300 mu l of methyl isobutyl ketone. Using 5-80 mg of either sorbents materials with a loading time of 2 min per sample preconcentration factors of copper ranging from 35-125 for Na-LTA and 3065 for Na-Fau were readily achieved related to the direct introduction of aqueous solutions into an atomic absorption spectrometer. To evaluate the performance of these materials, a flow injection system was used for samples of water from different sources, and the accuracy was assessed through recovery experiments and the analysis of certified reference materials. A parallel experiment was performed with polygosyl bonded silica reversed-phase sorbent with octadecyl functional groups (RP-C-18) as sorbent in the minicolumn in order to study the performance of this. well-known material as a reference for the new sorbents. The 3 sigma detection limits, relative standard deviation and linear calibration graphs were, respectively, 0.1 ng ml(-1), 2.6% and 2.5-30 ng ml(-1) for Na-LTA and 0.4 ng ml(-1), 2.8% and 2.5-40 ng ml(-1) for Na-Fau for preconcentration times of 2 min. (C) 2000 Elsevier Science B.V. All rights reserved.