Mixed hemimicelle solid-phase extraction based on magnetic carbon nanotubes and ionic liquids for the determination of flavonoids

A novel mixed hemimicelles solid phase extraction (SPE) based on magnetic carbon nano-tubes (MCNTs) and ionic liquid (IL) is developed for the simultaneous extraction and determination of trace flavonoids in spiked human urine: In this novel SPE, the formation of C(16)mimBr with mixed hemimicelles on the surface of MCNTs@SiO2 nanoparticles (NPs) causes retention of analytes by strong hydrophobic, pi-pi and electrostatic interactions. This SPE technique combines the advantages of mixed hemimicelles and MCNTs. In order to establish the guidelines for the preparation of mixed hemimicelles on composite materials, different main factors affecting the preconcentration of analytes, such as material type, amount of surfactant, pH of solution, ionic strength, extraction time, desorption condition and regeneration property, were investigated and optimized. Under the selected conditions, the accuracy of the method was evaluated by recovery measurements on spiked samples, and good recoveries with low relative standard deviations from 3.5% to 4.9% were achieved. No interferences were caused by endogenous compounds in human urine. For our knowledge, this is the first development of a mixed hemimicelles SPE based on MCNTs and IL for the extraction of trace analytes in complex biological samples. (C) 2014 Elsevier Ltd. All rights reserved.