Graphene oxide and reduced graphene oxide as novel stationary phases via electrostatic assembly for open‐tubular capillary electrochromatography

Abstract

We present here the application of graphene oxide (GO) and reduced graphene oxide (GOOH) sheet as novel stationary phases for open-tubular CEC (OTCEC) separation based on electrostatic assembly. The inner walls of a bare capillary column was first modified by ionic assembly of poly (diallyldimethylammonium chloride) (PDDA), and then negatively charged GO or GOOH was easily assembled on a positively charged interior walls of the capillary by electrostatic force. Scanning Electron Microscope images showed that GO and GOOH can still maintain sheet-layer-like structure when coated onto the capillary via electrostatic assembly. The chromatographic properties of the GO and GOOH coated columns were evaluated via OTCEC separations of various kinds of analytes, including three acid nitrophenol isomers, three basic nitroaniline isomers, and four neutral PAHs. Efficient separations of all the analytes were achieved with optimized buffer pH and organic additive. The reproducibility and stability of the GO or GOOH coated columns were investigated. Our results indicate the capability of application GO or GOOH sheet in OTCEC separation, which can be coated on the inner wall of fused-silica capillary via electrostatic assembly.

Carboxyl modified magnetic nanoparticles coated open tubular column for capillary electrochromatographic separation of biomolecules

“…However, due to the limited amount of stationary phase coating, low phase ratio and sample capacity of OT columns are the primary drawbacks and restrict their widespread application in electrochromatographic separations. To overcome these shortcomings, a series of innovative approaches such as sol-gel derived phases [4,5], etching [6], porous layers [7,8] and nanoparticles (NPs) phases [9][10][11][12][13][14][15][16][17][18][19] have been developed to increase the inner surface area of columns and enhance the stationary/mobile phase interactions in OT-CEC separations. Among these approaches, NPs modified OT columns show a great promise to enhance the separation efficiencies of complex samples since NPs possess larger surface-to-volume ratio.…”

“…A semipermanent coating is based on the strong physical adsorption between coating material and the capillary wall, which can effectively avoid the loss of stationary phase [31]. Recently, poly(diallydimethylammonium chloride) (PDDA) has been widely used to fabricate semipermanent coating in OT-CEC via electrostatic attraction [10][11][12]14,15]. PDDA is a water-soluble cationic polyelectrolyte, which has a wealth of highly hydrophilic and positively charged quaternary ammonium groups.…”

“…PDDA is a water-soluble cationic polyelectrolyte, which has a wealth of highly hydrophilic and positively charged quaternary ammonium groups. Some NPs have been applied in OT-CEC as novel stationary phases by means of electrostatic self-assembly between PDDA and NPs, such as graphene [10], graphene oxide and reduced graphene oxide [11,12], nano-SiO 2 [14] and cyclodextrin-modified gold NPs [15].…”

“…For the past two decades, NPs with unique physical and chemical properties have made a significant contribution to the development of stationary phases in CEC, such as carbon NPs [9][10][11][12], silica NPs [13,14], metallic and metal-oxide NPs [15][16][17][18], and polymer NPs [1]. As one kind of extensively studied NPs, magnetic nanoparticles (MNPs) have received great attention for their superior characteristics such as good dispersion, excellent biocompatibility [20], high field irreversibility, ease of preparation, high ratio of surfaceto-volume [19] and remarkable physicochemical stability.…”

Graphene Oxide Nanoparticles and Their Influence on Chromatographic Separation Using Polymeric High Internal Phase Emulsions

“…The enhanced conductive properties allow for interesting electrochemically functionalised separations. Such modifications have already been demonstrated in the separation of acid nitrophenol isomers, basic nitroaniline isomers, and neutral PAHs using open tubular capillary electrochromatography (OTCEC) [40]. To date however, polyHIPE modifications with GONPs have not been explored.…”