Gas Chromatographic Characterization of Silica-Based Reversed-Phase Sorbents for Solid Phase Extraction

The interaction properties of some alkylsiloxane-, phenylsiloxane- and cyanopropylsiloxane-bonded silica-based sorbents for solid phase extraction are characterized. The linear solvation energy relationship model is used to estimate the characteristic interaction constants of the sorbents, s (dipolarity/polarizability), a (hydrogen bonding basicity), b (hydrogen bonding acidity), r (polarizability), and l (methylene selectivity). For nonpolar alkyl-bonded sorbents, the l constant is the largest, indicating that the cavity/dispersive interactions term is the dominant term favoring retention on the sorbent. Other interaction terms play minor roles in retention. For the polar cyanopropyl-bonded sorbent the s and a constants are the largest and are essentially equal, followed by l, r and b constants. For the phenyl-bonded sorbent, the b coefficient is the largest, followed by a quite large a coefficient.