Pressurized capillary electrochromatography separation of peptides with strong cation exchange and hydrophilic interaction

Abstract

Pressurized capillary electrochromatography separation of peptides with strong cation exchange and hydrophilic interaction A pressurized capillary electrochromatography (pCEC) instrument with solvent gradient capability has been used for the separation of a peptide mixture. Retention mechanism and selectivity of the peptides were studied by pCEC using a strong cation exchange (SCX) column. The effects of applied voltage, supplementary pressure, organic modifier concentration, ionic strength, and pH value on pCEC separation were investigated. It was found that the retention mechanism of the peptides in this system is based on a mixed mode of hydrophilic interaction, strong cation exchange, and electrophoresis. Compared with the separation results obtained by reverse phase pCEC and capillary electrophoresis (CE), this mixed-mode pCEC is more powerful for the separation of hydrophilic peptides with similar charge-to-mass ratio.

Fingerprint analysis of Rhizoma chuanxiong by pressurized capillary electrochromatography and high‐performance liquid chromatography

“…However, the pCEC system became less stable due to resulting Joule heat of the high applied voltage. A decrease in resolution was observed when the applied voltage was at −15 kV and at the same time, when the applied voltage was +15 kV, small bubbles were observed due to the differences in velocity of the liquid eluent between the packed and unpacked sections of the capillary and the resulting Joule heat (Poppe, 1997;Zhang et al, 2003). The peak of the measured compound also varied when different voltages were applied; for example, ferulic acid exhibited a single peak when negative voltage was applied, and the single peak split into two peaks when positive voltage was applied.…”

“…CEC is a hybrid technique that combines the selectivity of HPLC and the separation efficiency of CE. However, in practice, when CEC is used without pressure, often on a commercial CE instrument, there were problems associated with bubble formation in CEC, occurring initially in the unpacked section of the capillary, probably as a result of differences in velocity of the liquid eluent between the packed and unpacked sections of the capillary (Poppe, 1997;Zhang et al, 2003) and column dry-out. The use of supplementary pressure has proved effective to stabilize the flow conditions.…”

“…Compared with traditional HPLC and CE, the mobile phase in the pCEC system is driven by a pressurized flow and an electro-osmotic flow (EOF) simultaneously, reducing band broadening and improving separation efficiency. Now pCEC has become an attractive technique for pharmaceutical analysis (Zhang et al, 2003;Lue et al, 2007) because of its combination of the inherent advantages of two major separation techniques. Therefore, we intend to develop a characteristic fingerprint of Rhizoma chuanxiong using pCEC and HPLC simultaneously for identifying the raw herb.…”

Analysis of trans-Resveratrol in Grapes by Micro-High Performance Liquid Chromatography

“…25,26 A continuous flow is generated by merging two flows in a mixer. After splitting in a T-piece, the flow enters a capillary column through a 20 nL rotary-type injector (Valco, Houston, TX) under constant pressure controlled by a back-pressure regulator.…”

Preparation and application of monolithic beds in the separation of selected natural biologically important compounds

“…In the literature different mechanisms were applied [12], for example: size exclusion (SEC) [78], reversed-phase [14], ionexchange, affinity [79][80][81], hydrophobic interaction (HIC) [47,82], or hydrophilic interaction [81,83,84]. The SEC mechanism was demonstrated by the group of Lee during the separation of proteins and peptides on poly(polyethylene glycol methyl ether acrylate-co-polyethylene glycol diacrylate) monolith.…”