Effect of Embedded Polar Groups on Reversed-Phase Chromatographic Behavior

Library Number:
980553
Author(s):
Edouard S.P. Bouvier*, Bonnie A. Alden, Thomas H. Walter, John E. O''Gara, & Uwe D. Neue
Source:
HPLC''98, St. Louis, May 3-8, 1998, Lecture #L-1204
Content Type:
Orals/Lectures
Content Subtype:
HPLC
Compounds:
Uracil; Benzene; Toluene; Ethylbenzene; Propylbenzene; Butylbenzene; Propranolol; Butyl paraben; Dipropylphthalate; Naphthalene; Amitriptyline; Acenaphthene; di-substituted benezenes;
Column:
SymmetryShield RP8,RP18 Symmetry C18
Dimensions:
3.9 x 150 mm
Novel reversed-phase chromatographic stationary phases have been recently developed which contain polar groups embedded in the alkylsilane chain. Chromatographic sorbents have been synthesized by reacting silica with various O-[3-(chlorodimethylsilyl)-propyl]-N-alkylcarbamates. A systematic study has been performed to compare chromatographic retention behavior of various analytes on these phases with their corresponding linear alkyldimethylsilyl reversed phases. Incorporation of the embedded carbamate group into the alkyl chain has been shown to induce changes in chromatographic selectivity for a variety of analytes. In general, the carbamate phase provides for reduced retention of basic analytes, but slightly increased retention for acidic compounds. This behavior may be rationalized by considering the interactions of the analytes with both the polar bonded phases and the residual silanols. Previously, the octyl carbamate phase has been found to provide advantagesover conventional C8 phases when performing HPLC in highly aqueous mobile phases. This has been attributed to the reduced contact angle of the carbamate phase with water, which prevents extrusion of mobile phase from the pores of the packing material. The effect of alkyl chain length on chromatographic performance in aqueous mobile phases will be investigated. [File annotated with notes.]

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