Abstract
A novel ion imprinted polyvinylimidazole-silica hybrid copolymer (IIHC) was synthesized and used as a selective solid sorbent for Pb 2+ ions preconcentration using an on-line solid phase extraction (SPE) system coupled to TS-FF-AAS. The ionic hybrid sorbent was prepared using 1-vinylimidazole and 3-(trimethoxysilyl)propylmethacrylate as monomers, Pb 2+ ions as template, tetraethoxysilane as reticulating agent and 2,2′-azobis-isobutyronitrile as initiator. The best on-line SPE conditions concerning sorption behavior, including sample pH (6.46), buffer concentration (9.0 mmol L −1), eluent (HNO 3) concentration (0.5 mol L −1) and preconcentration flow rate (4.0 mL min −1), were optimized by means of full factorial design and Doehlert matrix. The analytical curve ranged from 2.5 to 65.0 μg L −1 ( r = 0.999) with limit of detection of 0.75 μg L −1; the precision (repeatability) calculated as relative standard deviation ( n = 10) was 5.0 and 3.6% for Pb 2+ concentration of 10.0 and 60.0 μg L −1, respectively. From on-line breakthrough curve, column capacity was 3.5 mg g −1. Preconcentration factor (PF), consumptive index (CI) and concentration efficiency (CE) were 128.0, 0.16 mL and 25.6 min −1, respectively. The selective performance of the sorbent, based on relative selectivity coefficient, was compared to NIC ( non imprinted copolymer) for the binary mixture Pb 2+/Cd 2+, Pb 2+/Cu 2+ and Pb 2+/Zn 2+. The results showed that ion imprinted polyvinylimidazole-silica hybrid polymer had higher selectivity for Pb 2+ than NIC at 64.9, 16.0 and 8.8 folds. The developed method was successfully applied for highly sensitive and selective Pb 2+ determination in different kinds of water samples, parenteral solutions and urine. Accuracy was also assessed by analyzing certified reference fish protein (DORM-3) and marine sediment (MESS-3 and PACS-2) with satisfactory results.
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