LVSEP Analysis of Cationic Analytes in Cationic Polymer-Coating Microchannel Prepared by Vacuum-Drying Method

Abstract

To improve the detection sensitivity of cationic analytes with simple experimental procedures in microchip electrophoresis (MCE), large-volume sample stacking with an electroosmotic flow (EOF) pump (LVSEP) was performed in polymer-coated microchannels. At first, cationic polybrene (PB) was employed as the coating polymer to reverse the EOF. In the LVSEP analyses, however, the PB-coated microchannel gave insufficient enrichments and broader peaks for cationic standard dyes. By the application of neutral poly(vinyl alcohol) and cationic poly(allylamine) mixture-coating, on the other hand, good enrichments of histamine were achieved by LVSEP with a sensitive enhancement factor of 120.

LVSEP Analysis of Cationic Analytes in Non-Aqueous Media on Cationic Polymer-Coated Channel Microchips

“…MCE experiments were performed with the same apparatus as the previous report [10]. In the LVSEP analysis on the straight-channel chip, a sample solution was introduced into the entire channel by manually using a syringe.…”

“…To overcome this limitation, various on-line sample preconcentration methods have been developed [3][4][5][6][7][8]. In our research group, a large volume sample stacking with electroosmotic flow pump (LVSEP) technique has been applied to enhance the sensitivities [9][10][11][12][13][14][15][16][17][18][19]. LVSEP involves the enrichment of the sample injected into the whole separation column by the field-amplified sample stacking, and the separation of the focused analytes without polarity switching due to the changes in the velocity of electroosmotic flow (EOF) between at the stacking and at the separation step.…”

“…In the LVSEP analysis of cations, hence, the channel surface needs to be weakly and positively charged by modifying cationic polymers for inverting the direction of EOF. In our previous study, it was demonstrated that the application of polybrene (PB) or PVA + poly(allylamine) (PAA) coating is effective for the LVSEP analysis of cationic analytes [10,16].…”

“…At first, the straight-microchannel is coated with cationic polymers to obtain weakly and positivelycharged surface (Fig. 1a) [10,16]. The channel is filled with a cationic sample solution dissolved in neat organic solvent such as DMSO and methanol (Fig.…”

Nonaqueous Capillary Zone Electrophoresis for Polyesters and Polyamides Using Hexafluoroisopropyl Alcohol as Electrophoretic Medium

“…Liquid chromatography (LC) and capillary electrophoresis (CE) are methods used for separating a wide variety of compounds, and both fundamental and applicational studies are still progressing [1][2][3][4][5][6][7][8][9][10][11]. Focused on polymers as analytes, biopolymers such as proteins and DNAs have been separated frequently in both LC and CE, and many analytical protocols have been developed.…”