Journal
JOURNAL OF CHROMATOGRAPHY A
Volume 1217, Issue 42, Pages 6475-6483Publisher
ELSEVIER SCIENCE BV
DOI: 10.1016/j.chroma.2010.08.037
Keywords
Carbon coated alumina; Carbon clad zirconia; Stationary phase; Chemical vapor deposition; HPLC; Retentivity
Funding
- National Institute of Health [GM 054585]
- Institute of Technology Characterization Facility, University of Minnesota, NSF
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The retention of polar compounds, the separation of structural isomers and thermal stability make carbonaceous materials very attractive stationary phases for liquid chromatography (LC). Carbon clad zirconia (C/ZrO2), one of the most interesting, exhibits unparalleled chemical and thermal stability, but its characteristically low surface area (20-30 m(2)/g) limits broader application as a second dimension separation in two-dimensional liquid chromatography (2DLC) where high retentivity and therefore high stationary phase surface area are required. In this work, we used a high surface area commercial HPLC alumina (153 m(2)/g) as a support material to develop a carbon phase by chemical vapor deposition (CVD) at elevated temperature using hexane vapor as the carbon source. The loading of carbon was varied by changing the CVD time and temperature, and the carbon coated alumina (C/Al2O3) was characterized both physically and chromatographically. The resulting carbon phases behaved as a reversed phase similar to C/ZrO2. At all carbon loadings, C/Al2O3 closely matched the unique chromatographic selectivity of carbon phases, and as expected the retentivity was increased over C/ZrO2. Excess carbon - the amount equivalent to 5 monolayers - was required to fully cover the oxide support in C/Al2O3, but this was less excess than needed with C/ZrO2. Plate counts were 60,000-76,000/m for 5 mu m particles. Spectroscopic studies (XPS and FT-IR) were also conducted; they showed that the two materials were chemically very similar. (C) 2010 Elsevier B.V. All rights reserved.
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