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

Abstract:

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 μl 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 30-65 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-C18) as sorbent in the minicolumn in order to study the performance of this well-known material as a reference for the new sorbents. The 3σ 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.