title: Fine-tuning of electromembrane extraction selectivity using 18-crown-6 ethers as supported liquid membrane modifiers.
abstract: Selectivity of electromembrane extractions (EMEs) was fine-tuned by modifications of supported liquid membrane (SLM) composition using additions of various 18-crown-6 ethers into 1-ethyl-2-nitrobenzene. Gradually increased transfer of K(+) , the cation that perfectly fits the cavity of 18-crown-6 ethers, was observed for EMEs across SLMs modified with increasing concentrations of 18-crown-6 ethers. A SLM containing 1% w/v of dibenzo-18-crown-6 in 1-ethyl-2-nitrobenzene exhibited excellent selectivity for EMEs of K(+) . The established host-guest interactions between crown ether cavities in the SLM and potassium ions in donor solution ensured their almost exhaustive transfer into acceptor solution (extraction recovery ∼92%) within 30 min of EME at 50 V. Other inorganic cations were not transferred across the SLM (Ca(2+) and Mg(2+) ) or were transferred negligibly (NH4 (+) , Na(+) ; extraction recovery < 2%) and had only subtle effect on EMEs of K(+) . The high selectivity of the tailor-made SLM holds a great promise for future applications in EMEs since the range of similar selective modifiers is very broad and may be applied in various fields of analytical chemistry.
authors.affiliation: Institute of Analytical Chemistry, Academy of Sciences of the Czech Republic, Brno, Czech Republic.
authors.forename: Andrea
authors.initials: A
authors.lastname: Šlampová
authors.forename: Pavel
authors.initials: P
authors.lastname: Kubáň
authors.forename: Petr
authors.initials: P
authors.lastname: Boček
mesh_terms: D043844:Crown Ethers / Q000737:chemistry*; D055664:Electrochemical Techniques / Q000295:instrumentation* / Q000379:methods*; D008567:Membranes, Artificial
chemical_list: D043844:Crown Ethers; D008567:Membranes, Artificial; C015762:18-crown-6
keywords: 18-Crown-6 ethers; Electromembrane extraction; Inorganic cations; Selectivity modification