A new and selective capillary column coated with cationic diazacrown ether for separation of organic and inorganic anions by capillary electrophoresis

Abstract

A new coated capillary has been introduced for capillary electrophoretic separation of anions by using a positively charged diazacrown ether with a 12-membered ring. A positive charge spread over the inner capillary surface led to a substantial anodic electroosmotic flow (EOF) over the range of migrating buffer of pH 2-11. Under the optimum conditions of 25 mM phosphate buffer at pH 7, the diazacrown-coated capillary showed a successful simultaneous separation of 7 inorganic anions and 13 aromatic anions (including positional isomers) in less than 15 min. The migration times of the sample anions and EOF marker for consecutive runs on a single column were highly reproducible, giving a relative standard deviation of 1%. Theoretical treatment of the migration behavior clearly demonstrated that ion association between the diazacrown and analyte anions is strongly dependent on the nature of the functional groups of anions (e.g., sulfonate groups > carboxyl groups) and the number of negative charges (e.g., trivalent anions > divalent anions > monovalent anions) on the analyte.

In-situ sampling of available calcium using diffusive gradients in thin-films technique based on benzo-crown ether-functionalised silica as the binding agent

“…The whole of protonated BCES was unsuitable for the complexation of Ca 2þ ion, resulting in a non-efficient accumulation ability of BCES for Ca 2þ (Simionca et al 2012). Similar behaviour for the binding of metal ions with other sorbents functionalised with crown ether was observed previously (Mori et al 2003;Strzelbicki and Bartsch 1981;Kafashi et al 2015;Zhao and Bartsch 1995). The values of C DGT /C SOLN in the range from 1.008 AE 0.016 to 1.064 AE 0.029 were independent of ionic strength (NaCl) from 0.001 to 0.1 mol L À1 (Fig.…”

Capillary electrophoresis separation of peptide diastereomers that contain methionine sulfoxide by dual cyclodextrin‐crown ether systems†

“…It may be speculated that the protonated Kryptofix® 22 is adsorbed to the capillary wall, thus, modifying the EOF, while this occurs to a lesser extent in case of the smaller Kryptofix® 21 crown ether. Diaza‐crown ethers have been used for EOF modification and reversal for the separation of inorganic ions as bifunctional modifiers . Migration times increased as compared to the presence of the neutral crown ethers despite the fact that the charge of the complexes should be higher in the case of the protonated diaza‐crown ethers.…”

Element Speciation Analysis Using Capillary Electrophoresis: Twenty Years of Development and Applications

“…Among these are a column packed with a polymer-based or a silica-based anion-exchange (AE) material; a histidine-functionalized silica converted into the Cu(II)–histidine complex, which apparently acts as a ligand exchanger; fused-silica capillaries coated with commercial AE latex particles, , a macrocyclic polyamine, or a diazacrown ether; and, finally, a cationic polymer possessing anionic selectivity. The analytes studied include common inorganic forms of iodine, bromine, chlorine, and nitrogen, − as well as a series of As, Cr, and Se species . The zwitterionic character of a commercially coated ZIC-capillary makes it a reasonable candidate for chiral separations .…”