A poly(glycidyl-co-ethylene dimethacrylate) nanohybrid modified with β-cyclodextrin as a sorbent for solid-phase extraction of phenolic compounds

A hybrid material made of beta-cyclodextrin anchored to a polymeric network is described and evaluated as a sorbent for solid-phase extraction of phenolic compounds (phenol, cresol isomers, 2-methoxy-4-vinylphenol, 4-ethylphenol, 4-vinylphenol, 4-ethylguaiacol, guaiacol, and eugenol). The polymeric backbone of the sorbent consists of a poly(glycidyl-co-ethylene dimethacrylate) network, whose surface has been modified with beta-cyclodextrin by a click-chemistry based procedure. The resulting material has been characterized by different techniques, and it has shown to be viable as a sorbent for its use in extraction cartridges. In this way, a method for the determination of the above analytes in tea has been validated. Under optimum conditions, the method has good repeatability, with coefficients of variation between 0.6 and 7.2%. In addition, recoveries from spiked samples at the level of 50 mu g L-1 are between 57 and 101%. The method has been then applied to the determination of phenolic compounds in the drinkable portion of infusions made from tea bags. The quantification has been carried out by using gas chromatography coupled to a mass spectrometry detector. Following their elution from the sorbent with a mixture of acetonitrile and methanol, the limits of quantification reached are between 4.6 and 400 mu g L-1. Results have been compared with those obtained with a reference method by using the paired t-test for comparing individual differences. The solid phase is reusable, and no cyclodextrin is lost during extraction due to its covalent anchoring to the polymeric support.