Fine‐tuning of electromembrane extraction selectivity using 18‐crown‐6 ethers as supported liquid membrane modifiers |
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Authors: | Andrea Šlampová Pavel Kubáň Petr Boček |
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Affiliation: | Institute of Analytical Chemistry, Academy of Sciences of the Czech Republic, Brno, Czech Republic |
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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 (Ca2+ and Mg2+) 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. |
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Keywords: | 18‐Crown‐6 ethers Electromembrane extraction Inorganic cations Selectivity modification |
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