Open‐tubular capillary electrochromatography using a capillary coated with octadecylamine‐capped gold nanoparticles

Abstract

Octadecylamine-capped gold nanoparticles (ODA-Au-NPs) were prepared and characterized by using UV-Vis adsorption spectrum, transmission electron chromatography (TEM), SEM, and FT-IR. A simple but robust hydrophobic coating was easily developed by flushing a capillary with a solution of ODA-Au-NPs, because the positive charges were carried by the nanoparticles which strongly adsorb to the negatively charged inner surface of a fused-silica capillary via electrostatic and hydrophobic interactions. The chromatographic characteristics of the coated capillary was investigated by varying the experimental parameters such as buffer pH, buffer concentration, and percentage of organic modifier in the mobile phase. The results show that (i) resolution between thiourea and naphthalene is almost the same when comparing the electrochromatograms obtained using pH 7 buffer as mobile phase after and before the capillary column was operated using pH 11 and 3 mobile phase; (ii) no significant changes in retention time and deterioration in peak efficiency were found after 60 runs of test aromatic mixtures; and (iii) column efficiency up to 189 000 theoretical plates/meter for testosterone was obtained. All of the results indicated that the coating could act as a stable stationary phase for open tubular CEC as well as for bioanalysis.

Multi‐walled carbon nanotube composites with polyacrylate prepared for open‐tubular capillary electrochromatography

“…Some Jian-Lian Chen Te-Ling Lu Yi-Chen Lin nanomaterials, including latex [11], lipoprotein [12,13], silica [14,15], titanium oxide [16,17], gold [18][19][20], and carbon nanotubes (CNT) [21][22][23][24][25], have been used in OT-CEC. However, only a few examples involved in chemical bonding of these materials onto OT capillaries exist.…”

Permanent gold nanoparticle coatings on polyelectrolyte multilayer modified capillaries for open-tubular capillary electrochromatography

“…Thus, the coating material must be present in the electrolyte during a separation. A semipermanent coating is formed by the strong physical adsorption of coating material to the capillary wall, thus the addi- tion of the coating material to the running buffer is not necessary [15]. Although physical adsorption has a simple and rapid coating procedure, the short lifetime of these coatings is a problem that cannot be overcome easily.…”

“…Moreover, alkanethiols can bind to gold to form highly ordered and densely packed monolayers. AuNPs have been used to modify the surface of micron spheres [39,40] and bare fused silica capillaries [8][9][10]15] through a chemical bonding technique and served as good stationary phase for chromatographic separation.…”

Tunable thick porous silica coating fabricated by multilayer-by-multilayer bonding of silica nanoparticles for open-tubular capillary chromatographic separation

“…Compared to other materials, nanoparticles have the merits of large surface area and ease of preparation. Therefore, nanoparticles of silica [30], gold [26,[31][32][33][34][35], titanium dioxide [36][37][38], and grapheme oxide nanosheets [39][40][41] have been immobilized onto the inner surface of capillary column. However, although these types of nanoparticles have been used successfully for chromatographic separation, in most cases, columns were coated with only a single layer.…”