Use of coated capillaries for the electrophoretic separation of stereoisomers of a growth hormone secretagogue

Abstract

The diastereoisomeric separation of peptidomimetics of hexarelin, a strong growth hormone secretagogue, in CE has been studied. Highly sulfated-gamma-CD was found to be an appropriate selector for the separation of the stereoisomers. However, non-repeatable analyses were obtained on bare fused silica capillary due to the progressive adsorption of the analytes on the capillary wall. Two types of polyelectrolyte coating agents were tested to prevent this phenomenon. Coating with neutral polyethylene oxide was found to be efficient but resulted in a very long analysis time (about 40 min). Coating with cationic poly(diallyldimethylammonium) chloride was found both to prevent analyte adsorption, reduce analysis time and alter separation selectivity. EOF measurement revealed that the highly sulfated-gamma-CDs were strongly adsorbed on the poly(diallyldimethylammonium) chloride coating surface yielding a stable strong cathodic EOF, which considerably reduced analysis time (about 12 min). Very good repeatability of analysis was obtained (RSD(migration time)<1%).

Characterizing stability of “click” modified glass surfaces to common microfabrication conditions and aqueous electrolyte solutions

“…1 Unlike physical modification methods such as grinding, polishing, or thermal treatments, chemical modification of surfaces also changes the surface chemistry and chemical composition in contrast to the bulk material. 1 Several different surface coatings 2,6, [17][18][19][20][21] have been developed for applications in microchip or capillary electrophoresis, [22][23][24][25][26][27] a more common application for microfluidics and nanofluidics. In addition to use in separations, surface modification has been used to assist mixing in microfluidic devices by introducing heterogeneous surfaces 28 with patterned gradients in z (zeta) potentials.…”

Optimization of the enantioseparation of a diaryl‐pyrazole sulfonamide derivative by capillary electrophoresis in a dual CD mode using experimental design

“…To overcome these adverse effects on analytical performance, successive multiple ionic polymer layers coating of the capillary was used in order to mask its silanols groups. The use of a cationic SMIL coating was deemed the most suitable strategy to prevent adsorption of the cationic amino‐β‐CD, due to electrostatic repulsion forces involved, prior to developing a CZE method . Hence, the performance of a 5‐layers successive anionic and cationic polyelectrolyte coating was investigated.…”

Use of Sulfated Cyclofructan 6 and Sulfated Cyclodextrins for the Chiral Separation of Four Basic Pharmaceuticals by Capillary Electrophoresis

“…α‐, β‐, γ‐Cyclodextrins (α‐, β‐, γ‐CDs) and their derivatives are the most frequently used chiral selectors in CE . The mechanism is based mainly on the inclusion or incorporation of analytes, or at least a part of the analytes, in a hydrophobic basket of the various CDs .…”

“…4 α-, β-, γ-Cyclodextrins (α-, β-, γ-CDs) and their derivatives are the most frequently used chiral selectors in CE. [5][6][7][8][9][10][11][12][13][14][15][16] The mechanism is based mainly on the inclusion or incorporation of analytes, or at least a part of the analytes, in a hydrophobic basket of the various CDs. 17 Other important chiral selectors include macrocyclic antibiotics, 18 proteins, 2 chiral micelles, 19 and chiral crown ether.…”