Stir rod sorptive extraction with monolithic polymer as coating and its application to the analysis of fluoroquinolones in honey sample

A stir rod sorptive extraction (SRSE) with monolithic polymer as coating was proposed to avoid the friction loss of coating during the stirring process. In our study, poly(2-acrylamide-2-methylpropanesulfonic acid-co-octadecyl methacrylate-co-ethylene glycol dimethacrylate) [poly(AMPS-co-OCMA-co-EDMA)] monolithic polymer was used as a coating of SRSE. The effect of concentration of porogen on SRSE performance was studied. Four fluoroquinolones (FQs) were selected as testing analytes to evaluate the extraction efficiency of SRSE. To achieve the optimum extraction conditions of SRSE towards FQs, several parameters, including extraction time, extraction temperature, stirring rate, sample solution pH and contents of inorganic salt in the sample solution were investigated. Under the optimized conditions of SRSE, a method for the determination of FQs in honey sample was proposed based on the combination of SRSE with liquid chromatography and electrospray ionization mass spectrometry (SRSE/LC/ESI-MS). The detection limits (LODs) of the proposed method for four FQs ranged from 0.06 to 0.14 ng/g and the recoveries were in the range of 70.3–122.6% at different concentrations for honey samples. Good method reproducibility was found as intra- and inter-day precisions, yielding the relative standard deviations less than 11.9% and 12.4%, respectively. The results show that SRSE with poly(AMPS-co-OCMA-co-EDMA) monolithic polymer as coating possessed good extraction capacity towards FQs in honey samples. Finally, the monolithic polymer coated stir rod was demonstrated to be reused at least 60 times.