Probing Strong Adsorption of Solute onto C18-Silica Gel by Fluorescence Correlation Imaging and Single-Molecule Spectroscopy under RPLC Conditions
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- 作者：Zhenming Zhong ; Mark Lowry ; Gufeng Wang ; and Lei Geng
- 刊名：Analytical Chemistry
- 出版年：2005
- 出版时间：April 15, 2005
- 年：2005
- 卷：77
- 期：8
- 页码：2303 - 2310
- 全文大小：582K
- 年卷期：v.77,no.8(April 15, 2005)
- ISSN：1520-6882
文摘
Understanding molecular adsorption at a chromatographic interface is of great interest for addressing thetailing problem in chemical separations. Single-moleculespectroscopy and confocal fluorescence correlation imaging are used to study the adsorption sites of C18 silicabeads under RPLC chromatographic conditions. Theexperiments show that cationic molecule rhodamine 6Glaterally diffuses through the chromatographic interfaceof a C18 hydrocarbon monolayer and acetonitrile withoccasional reversible strong adsorptions. Fluorescencecorrelation imaging extracts the rare strong adsorptionevents from large data sets, revealing that the strongadsorption sites are randomly distributed throughout thesilica beads. Virtually every imaging pixel of silica beadsadsorbs molecules. Single-molecule spectroscopy of the584 strong adsorption events observed indicates that thestrong adsorptions persist on the time scales from severalmilliseconds to seconds, having an average desorptiontime of 61 ms. The strong adsorption events are rare,comprising 0.3% of the total observation time. The sizesof strong adsorption sites are within the optical resolutionof confocal imaging.