Capillary Electrochromatography of Cholesterol and Its Ester Derivatives

Abstract

Separation of cholesterol and its ester derivatives using micellar electrokinetic chromatography is a challenge due to the extreme hydrophobicity of these compounds. In this work, an isocratic capillary electrochromatography (CEC) method has been developed to separate a complex mixture of cholesterol and its 12-ester derivatives. The proportions of mobile phase (tetrahydrofuran, acetonitrile, water), as well as the effects of acid modifiers, buffer concentrations, voltage, and temperature on the separation of cholesterol derivatives were investigated. Addition of a polymeric surfactant, poly(sodium N-undecanoyl-L-glycinate), to the mobile phase reduced migration time and improved resolution of the analytes. The CEC method developed allows baseline separation of a complex mixture of cholesterol and 12 ester derivatives in less than 40 min. Finally, the method is applied to the characterization of cholesterol, cholesterol linoleate, and cholesterol oleate extracted from atherosclerotic plaque deposits in the arterial walls of a human aorta.

Capillary electrochromatography of Triton X‐100

“…4 shows that when increasing the Tris concentration over the range of 3.12-25.0 mM, the retention time increases due to a decrease in EOF. This decrease in EOF can be attributed to interactions of Tris with the silica surface that affects the thickness of the double layer and the zeta potential [20], which is a similar trend observed in our previous work [13]. When comparing the N over the same range, a general overall increase in plate number was observed (bar plot A).…”

Analytical separations in open‐tubular capillary electrochromatography

“…This revival of CEC is because it is a microcolumn electroseparation technique that combines the best features of high-performance liquid chromatography (HPLC) with those of high-performance capillary electrophoresis (HPCE). In essence, CEC mainly couples the high selectivity of HPLC and the high separation efficiency of HPCE [9][10][11][12][13][14][15]. This is because in CEC, the mobile phase solvent is transported through a capillary by the use of electroosmotic flow (EOF), which is induced by applying an electrical field across the capillary column.…”

“…It also offers wider selectivity and facilitates the separation of both neutral and charged compounds. The latter characteristic is because separation of analytes is based on their interactions with the stationary phase and, when charged, their electrophoretic mobility [4,[14][15][16][17][18][19][20][21].…”

CEC and EKC of natural compounds

“…Detection was accomplished by UV absorption at 200 nm. The system was tested on the extracts of human arteriosclerotic plaques, with cholesterol palmitate and cholesterol linoleate as the identified substances [14].…”