Development of an aptamer-functionalized sorbent for the selective and specific extraction of lead from environmental and biological samples.

An oligonucleotide-based sorbent was developed to enable the selective extraction of lead ions from serum and water samples. Two oligonucleotide sequences, previously reported in the literature for their high affinity toward Pb(II), were grafted onto CNBr-activated Sepharose, producing sorbents suitable for solid-phase extraction. Grafting efficiencies ranged from approximately 50 to 70%. Subsequent optimization focused on adjusting the percolation and washing conditions to ensure preferential retention of Pb(II) on the specific aptamer-modified supports, followed by controlled elution. The elution kinetic was studied to minimize the elution volume. Under optimized conditions, high selectivity was obtained, with mean extraction recoveries of 83 ± 2.7% and 79 ± 8% (n = 3) for the specific sorbents, compared to only 7-10% for the control sorbents. Other cations showed recoveries below 15%, confirming the strong specificity of the developed sorbents. The capacity of the most efficient sorbent was estimated at approximately 600 ng per 30 mg of support (≈30 µg/g), which is suitable for the selective extraction of trace amounts of Pb(II) from serum or water samples. Applying this support to real samples made it possible to determine Pb(II) levels of 6.3 µg/L for tap water, 2.7 µg/L for the Seine River water, and 87 µg/L for digested serum samples, while reducing matrix effects and minimizing ICP-MS instrument clogging.