TY - JOUR
T1 - Raman spectroscopy of octadecylsilane stationary phase conformational order
T2 - Effect of solvent
AU - Pemberton, Jeanne E.
AU - Ho, Mankit
AU - Orendorff, Christopher J.
AU - Ducey, Michael W.
N1 - Funding Information:
The authors are grateful for the support of this research by the Department of Energy, Office of Basic Energy Science (DE-FG03-95ER14546). The authors also express appreciation to Professor Michael F. Burke and International Sorbent Technologies for providing the stationary phase materials.
PY - 2001/4/13
Y1 - 2001/4/13
N2 - The effect of solvent on the conformation of alkyl chains of two octadecysilane-based stationary phases is probed using Raman spectroscopy. Spectral data indicate that the alkyl chains of commercially available polymeric and monomeric solid-phase extraction stationary phases are disordered to a varying extent by solvents of different polarity. For the polymeric octadecylsilane stationary phase, the polar solvents water, acetonitrile, methanol, acetone and isopropanol have little impact on the conformational order of the octadecylsilane bonded phase relative to air. However, the alkyl portion of this stationary phase is substantially disordered in the low-polarity solvents tetrahydrofuran, chloroform, benzene, toluene and hexane. The monomeric octadecylsilane stationary phase is less susceptible to disordering by solvents, although more disorder in the less polar solvents is also observed for this system. These results are interpreted in terms of the local surface bonding density and interchain spacing of these two stationary phases, and the ability of the solvent to penetrate the chains as a function of polarity. The results clearly demonstrate the ability of Raman spectroscopy to precisely indicate subtle changes in conformational order of alkylsilane stationary phases.
AB - The effect of solvent on the conformation of alkyl chains of two octadecysilane-based stationary phases is probed using Raman spectroscopy. Spectral data indicate that the alkyl chains of commercially available polymeric and monomeric solid-phase extraction stationary phases are disordered to a varying extent by solvents of different polarity. For the polymeric octadecylsilane stationary phase, the polar solvents water, acetonitrile, methanol, acetone and isopropanol have little impact on the conformational order of the octadecylsilane bonded phase relative to air. However, the alkyl portion of this stationary phase is substantially disordered in the low-polarity solvents tetrahydrofuran, chloroform, benzene, toluene and hexane. The monomeric octadecylsilane stationary phase is less susceptible to disordering by solvents, although more disorder in the less polar solvents is also observed for this system. These results are interpreted in terms of the local surface bonding density and interchain spacing of these two stationary phases, and the ability of the solvent to penetrate the chains as a function of polarity. The results clearly demonstrate the ability of Raman spectroscopy to precisely indicate subtle changes in conformational order of alkylsilane stationary phases.
KW - Raman spectrometry
KW - Solvent effects
KW - Stationary phases, LC
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U2 - 10.1016/S0021-9673(01)00569-6
DO - 10.1016/S0021-9673(01)00569-6
M3 - Article
C2 - 11355819
AN - SCOPUS:0035853594
VL - 913
SP - 243
EP - 252
JO - Journal of Chromatography A
JF - Journal of Chromatography A
SN - 0021-9673
IS - 1-2
ER -