The Study On The Application Of Magnetic Molecularly Imprinted Technology With Liquid Chromatography-tandem Mass Spectrometry Into Analyzing Samples

Molecularly imprinted polymers （MIPs） are synthetic polymers which have highlyspecific recognition ability for target molecules. In the recent few years, MIPs havereceived more and more considerable attention as new molecular recognitionmaterials, because the polymers have many incomparable advantages, such aspredetermination, high selectivity and broad applicability. MIPs are produced bygrowing a polymer around a molecule which is used as the template molecule in theprocedure. When the polymerization procedure has been finished, the templatemolecule is removed from the polymer, remaining molecular holes which can rebindthe template molecule on size, shape and functionality selectively and effectively.Nowadays, there are many applications of MIPs in the fields of chemistry, biologyand medicine.Among these applications, there is a special one which is the solid phaseextraction （SPE） method using MIPs as the solid sorbent. If some magneticnanoparticle materials are encapsulated into MIPs, the composite polymer which iscalled magnetic MIPs （MMIPs） are obtained successfully. These compositive MMIPscould be used to separate and concentrate chemicals more conveniently with the helpof an external magnetic field.In this study, the application of MMIPs in the analysis of antibiotics residue in milksamples and human plasma samples were investigated. The contents which this papercontained are as follows:1. The MMIPs has been prepared using penicillin V potassium （PENV） astemplate molecule, methacrylic acid as functional monomer, ethylene glycol dimethacrylate as crosslinking agent and Fe3O4magnetite as magnetic component.When the polymers were synthesized, the template molecule PENV was removedfrom the polymer by the methanol–acetic acid as elution solution. Then the MMIPswere used as sorbent for extracting the β-lactam antibiotics in the milk samples. Theβ-lactam antibiotics eluted from the MMIPs was separated and detected by a liquidchromatography-tandem mass spectrometry. The limits of detection for the β-lactamantibiotics were found to be1.6，2.8，1.9ng mL^-1, the recoveries for analytes were70.3–91.2%. The precision and accuracy for the proposed method should besatisfactory.2. A simple, selective and new method was successfully developed for thedetermination of melamine （MEL） in milk using MMIPs as solid sorbent. Theextraction procedure was performed in a single step by blending and stirring thesample, extraction solvent and the MMIPs. The experimental results showed that theMMIPs had high affinity and selectivity towards MEL which is template molecule.When the procedure of extraction was completed, the MMIPs adsorbing MEL wereseparated from the sample matrix by an external magnet. The MEL eluted from theMMIPs was analysed by a liquid chromatography-tandem mass spectrometry. Thelimit of detection was2.6ng mL^-1. The recoveries for the analytes of the five actualsamples were between88.0⁹5.8%and RSD was less than8.0%. The precision andthe limit of detection for the proposed method should be satisfactory.3. A simple and rapid method for the determination of roxithromycin in human plasmais presented. This synthetic method was different from the first and the secondexperiment, it was synthesise by the method of surface magnetic molecularly imprint.It was eveloped using the surface magnetic molecularly imprint polymers （MMIPs） assorbent for the extraction of roxithromycin from human plasma samples. The MMIPshas been prepared using roxithromycin as template molecule, tetramethylsilane asenwrapping agent, KH570as silane coupling agent, methacrylic acid as functionalmonomer, ethylene glycol dimethacrylate as crosslinking agent and Fe3O4magnetiteas magnetic component. Compared with the molecularly imprinted polymers, thesurface molecularly imprinted has higher eluting and adsorbing efficiencies, because the link location is not in the polymers but on the surface of the polymers. Theexperimental results showed that the MMIPs had high affinity and selectivity towardthe template molecule roxithromycin.