Evaluation of a novel silica-supported sol-gel sorbent prepared by a surface molecular imprinting technique for the selective separation of estazolam from human plasma

A molecular imprinting polymer (MIP) based on surface modification of silica gel was prepared via the sol-gel process with 3-aminopropyltriethoxysilane and phenyltrimethoxysilane as functional monomers, and estazolam as the template. The imprinted silica sorbent was characterized by Fourier Transform Infrared Spectroscopy, surface elemental analysis, and scanning electron microscopy (SEM). An MIP of agglomerated nano-particles with multi-pores was grafted onto the surface of the silica gel after hydrolytic condensation of the siloxane. The imprinted silica sorbent was used for solid phase extraction (SPE). Using water as loading solvent, the extraction efficiency for estazolam was higher compared to the use of an organic solvent. The imprinted silica sorbent was selective not only for the template, but also for the analogue. Compared to C-18-SPE and liquid-liquid extraction, the MIP-SPE was the most feasible technique for extraction of estazolam from human plasma; up to 98.7 +/- 1.2% recovery was achieved.