Coupled Transport of Pb(II) Ions Through a Bulk Liquid Membrane as a Preconcentration Method for Saline Natural Waters

Abstract

The vital importance of trace metal analysis in environmental water samples is widely recognised. In many cases, due to the low levels of trace metals in water samples and the high complexity of the matrixes (i.e. seawater), direct determination of trace metals is not always possible. A straightforward method for the preconcentration of trace Pb(II) ions in natural waters with salinity levels of >10 g/L has been developed by a liquid membrane containing 2-HBET in toluene. A lower detection limit of the method in comparison with other liquid membranes for this metal, the use of a cheap commercial organic ligand, as well as the possibility to measure by a common, simple and low cost technique, such as the atomic absorption spectroscopy, show the good results obtained. The efficiency of the process at optimal conditions was 83.7 +- 2.5% after 7 hours, with a precision of 3.1% at a confidence level of 95%, and the preconcentration factor was 20.45. The detection limit of the method was 0.391 microg/L of Pb(II). The liquid membrane system was successfully applied to the determination of lead in spiked saline samples and real seawater collected from the Algeciras bay (Cádiz, south Spain).