Extraction of lead ions by electromembrane isolation

A new microextraction approach namely electromembrane isolation (EMI) coupled with capillary electrophoresis (CE) and ultraviolet (UV) detection for determining lead (Pb) ions was developed. The EMI technique involved the use of a polypropylene hollow fiber whose channel was filled with a sodium dihydrogen phosphate/sodium tetraborate buffer solution of pH 8.1, immersed in 10 mL of an aqueous sample solution. A voltage of 300 V was applied across the hollow fiber wall for 15 min to extract Pb ions. The extract was then complexed with ethylenediamminetetracetic acid (20 mM EDTA solution, at pH 3.4) for CE analysis. Satisfactory linear dynamic ranges (0.1-10 mg L^-1), limits of detection (0.019 mg L^-1) and good repeatability (ranging from 4.9 to 15.6%, n = 3) were obtained. EMI exhibits good linearity with a correlation coefficient of 0.9935. The optimized EMI procedure was applied to determine the concentration of Pb²⁺ in various matrices, such as amniotic fluid, blood serum, lipstick and urine samples.