Surface molecularly imprinted polymers with synthetic dummy template for simultaneously selective recognition of nine phthalate esters

Abstract

Dummy template molecularly imprinted polymers (DMIPs) on silica gel particles for simultaneously selective recognition of nine phthalate esters have been prepared. A novel dummy template molecule with similar structural skeleton to the phthalate ester, diethyl N,N'-phthaloyl-bis(11-aminoundecanoate), has been designed and synthesized. The DMIP films were grafted on the surface of silica gel particles by a sol-gel process with 3-aminopropyltriethoxysilane (APTES) and tetramethoxysilane (TEOS) as functional monomer and cross-linker, respectively, and the obtained sorbents have been characterized by FTIR with diffuse reflectance accessory. The maximum static adsorption capacities of the DMIPs and NIP sorbents for the nine phthalate esters were 281 and 132mg/g respectively, and the results of dynamic adsorption showed that the adsorption equilibrium could be achieved about 5min for the DMIPs sorbents. The imprint factors of the sorbents ranged from 1.8 to 3.0 for eight of the phthalate esters except for Diamyl phthalate, which indicated that the DMIPs sorbents have high selectivity. The competitive experiments of the nine phthalates with some of their analogues on the sorbents illustrated that the DMIPs sorbents have high specificity for the phthalates. A GC-MS method for determination of the phthalate residues in fruit juice have been developed with the DMIPs as sorbents for the solid phase extraction (SPE) in the sample pretreatment procedures. The spiking recoveries of the phthalates were in the range of 72-100.2% with relative standard deviations lower than 10.2%. The results indicated that the obtained sorbents could specifically recognize the phthalates from complex matrices, which provide a new train of thought for preparing the DMIPs sorbents.

Keywords: Dummy template; Fruit juice; Phthalate esters; Solid-phase extraction; Surface molecularly imprinted polymers.