Capillary electrophoretic study of interactions of metal ions with crown ethers, a sulfated β-cyclodextrin, and zwitterionic buffers present as additives in the background electrolyte

Abstract

Stability constants of K, Na, Ca, and Ba with 18-crown-6, K, Na, Li with sulfated beta-cyclodextrin and K, Li, Ca, Mg, Sr, and Ba ions with ([2-hydroxy-1,1-bis(hydroxymethyl) ethyl]-amino)-1-propanesulfonic acid (TAPS) were determined by capillary electrophoresis and computed using a general least squares minimizing program CELET. The results for 18-crown-6 agreed well with those evaluated by graphical methods or reported in the literature. Previously unknown stability constants of sulfated beta-cyclodextrins and TAPS determined for alkali and alkaline earth metals show that sulfated beta-cyclodextrin interacts with monovalent metals allowing to manipulate their effective mobility. It interacts stronger with divalent metal cations. TAPS, as zwitterionic buffer widely used in various analytical, biochemical and other applications, forms complexes with alkali and alkaline earth cations, and although the stability constants are rather low, the equilibria should be taken into account when TAPS is used and metal cations are present in solution at the same time.

Study on the interaction of uranyl with sulfated beta‐cyclodextrin by affinity capillary electrophoresis and molecular dynamics simulation

“…According to Muzikář et al. , the binding constants of some monovalent cations (K, Na and Li) with S‐β‐CD were smaller than that of uranyl in this work, which possibly indicated much stronger interaction between divalent metal cations and S‐β‐CD and perhaps formed a stable inclusion complex. The apparent binding constant values for most small molecule drugs with S‐β‐CD reported in the literature are less than the uranyl cation in this work, which also revealed that the interaction between uranyl cation with sulfate groups of S‐β‐CD was relatively strong.…”

Protonated diamines as anion‐binding agents and their utility in capillary electrophoresis separations

“…The added CZE selectivity with cations typically comes from the use of complexing agents that provide a unique mobility based on the equilibrium binding. As an example, polyethers such as crown ethers serve as a keystone complexing ligand for cations 18–21. Polyethers provide selectivity for “harder” cations like the alkali metals and alkaline earth metals, and are attractive CZE additives because they are generally inexpensive, highly pure, nonconductive, water soluble, and/or optically transparent.…”

Affinity capillary electrophoresis and density functional theory applied to binding constant determination and structure elucidation of hexaarylbenzene-based receptor complex with ammonium cation

“…cyclodextrins or crown ethers are added to the BGE [14,28,29]. Addition of neutral receptor to the BGE decreases the effective mobilities of central ions due to their complexation with the large neutral receptor molecules.…”