Deep eutectic mixture membrane-based microextraction: HPLC-FLD determination of phenols in smoked food samples

A novel approach for effective sample pretreatment of food was developed. This approach was based on in situ deep eutectic mixtures formation between analytes (hydrogen bond donors) and choline chloride (a hydrogen bond acceptor) supported in a hydrophilic porous membrane. By this action, the analytes were extracted and retained into the hydrophilic porous membrane. Finally, the hydrophilic porous membrane containing the analytes was transferred into an aqueous phase and back-extraction occurred due to deep eutectic mixture decomposition in the aqueous phase. The developed approach was applied to the HPLC-FLD determination of phenols (phenol, o-cresol, p-cresol, eugenol, isoeugenol and guaiacol) in smoked food samples. The limits of detection, calculated from a blank test based on 3σ, were 0.3 µg kg^-1 for phenol, o-cresol, p-cresol; 0.6 µg kg^-1 for eugenol, isoeugenol; and 1 µg kg^-1 for guaiacol.