Ion-imprinted polymer

Uezu K, Nakamura H, Kanno J, Sugo T, Goto M, Nakashio F. Metal ion-imprinted polymer prepared by the combination of surface template polymerization with postirradiation hy gamma-rays. Macromolecules 1997 30 3888-3891. 

Carbon-based sorbents are relatively new materials for the analysis of noble metal samples of different origin [78-84]. The separation and enrichment of palladium from water, fly ash, and road dust samples on oxidized carbon nanotubes (preconcentration factor of 165) [83] palladium from road dust samples on dithiocarbamate-coated fullerene Cso (sorption efficiency of 99.2 %) [78], and rhodium on multiwalled carbon nanotubes modified with polyacrylonitrile (preconcentration factor of 120) [80] are examples of the application of various carbon-based sorbents for extraction of noble metals from environmental samples. Sorption of Au(III) and Pd(ll) on hybrid material of multiwalled carbon nanotubes grafted with polypropylene amine dendrimers prior to their determination in food and environmental samples has recently been described [84]. Recent application of ion-imprinted polymers using various chelate complexes for SPE of noble metals such as Pt [85] and Pd [86] from environmental samples can be mentioned. Hydrophobic noble metal complexes undergo separation by extraction under cloud point extraction systems, for example, extraction of Pt, Pd, and Au with N, A-dihexyl-A -benzylthiourea-Triton X-114 from sea water and dust samples [87]. 

Lesniewska, B., Kosinska, M., Godlewska-Zyfidewicz, B., Zambrzycka, E., Wilczewska, A. Z. Selective solid phase extraction of platinum on an ion imprinted polymers for its electrothermal atomic absorption spectrometric determination in environmental samples. Microchim. Acta 175, 273-282 (2011)... 

Daniel, S., Praveen, R.S., Rao, T.P. Ternary ion-association complex based ion imprinted polymers (IIPs) for trace determination of palladium(II) in environmental samples. Anal. Chim. Acta 570, 79-87 (2006)... 

Metal ion-imprinted polymers can be applied to the pre-concentration and the sample clean-up stages for metal ion determinations. Most elemental techniques such ICP-AES and ICP-MS suffer from the difficulties imposed by complex matrices that produce high dissolved salt concentrations. The use of imprinted resins for selective extraction of metal ions allows these methods to be used with greater flexibility and can significantly lower detection limits. The selectivity of some imprinted resins has been sufficient to allow selective and sensitive analyses of metal ions at ultra-trace levels using simpler and less expensive detection methods. By reducing the detection step to a simple colorimetric method, economy and simplicity are assured. The combination of imprinted polymer clean-up and colorimetric detection are attractive as the basis of an FIA system for the ultra-trace analysis of a specific metal or combination of metals. 

V. METAL ION IMPRINTED POLYMERS WITH SPECIFIC MORPHOLOGIES... 

The evolution of metal ion imprinting has been toward increasing selectivity at the expense of some exchange capacity. This trend is directed by the predominantly analytical applications of metal ion-imprinted polymers. The application of metal ion imprinted resins to problems in chemical analysis as chemical sensors is still just beginning. There have been some dramatic successes, but the field is still small and not very well recognized. Additional metal complexes available for imprinting are seen in Fig. 4 and 5. 

Metal ion imprinted polymers have yet to be characterized in sufficient detail. This lack of characterization is starting to be remedied. The associated field of ionomers [43] gives clues toward the direction some of these new efforts should take. This is especially relevant since characterization of metal ion-imprinted polymers has revealed that some of the metal ions are trapped in inaccessible locations... 

A comprehensive overview of preconcentration techniques for uranium (VI) and thorium (IV) prior to analysis was published (Prasada Rao et al. 2006). The multitude of off-line techniques that were reviewed includes liquid-liquid extraction, liquid membranes, ion exchange, extraction chromatography, flotation, absorptive electrochemical accumulation, solid-phase extraction (SPE), and ion imprinting polymers. In addition, online preconcentration methods for uranium, thorium, and mixtures of the two are also briefly surveyed. This overview includes over 100 references and is a good source for finding a suitable preconcentration technique with regard to the enrichment factor, retention and sorption capacity, method validation, and types of real samples. The review article focused on samples in which the uranium was already in solution so that digestion procedures for solid samples were not discussed (Prasada Rao et al. 2006). 

A new electrochemical detection strategy based on the adsorption behavior of nanostructured materials toward HMIs has been introduced to enhance the selectivity and sensitivity of electrochemical sensing platform. Various nanostructured materials including nanoscaled carbon, nanostructured metal oxides, micro/nanoporous ion-imprinted polymer, etc. have been explored for their use as electrode modifiers. We believe that the evolvement of adsorption behaviour-intrigued nanostructured materials-based electrochemical systems will lead to the development of novel HMIs detection tools with interest for applications in field such as environmental monitoring and other safety and security controls. The concept is also helpful to... 

Ozkutu, EB Ersoz, A Denizli, A. Preconcentration of phosphate ion onto ion-imprinted polymer. Journal of Hazardous Materials, 2008,157,130-136. 

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