Quartz Crystal Microbalance Sensor Based On Molecularly Imprinted Polymer For Metolcarb Determination

Metolcarb is an important N-methylcarbamate pesticide which is widely used in agricultural production.It may pass through the skin,respiratory and digestive tract into the body,leading to headaches,nausea,paralysis of limbs or other diseases.Until recently,analytical methods for metolcarb residue in complex samples were generally based on high performance liquid chromatography(HPLC),high performance liquid chromatography tandem mass spectrometry(HPLC-MS/MS),enzyme-linked immunosorbent assay(ELISA).Nevertheless,HPLC and HPLC-MS/MS needed to consume a large amount of organic solvent,enzymes or antibodies used in ELISA were inconvenient to store.Therefore,it is necessary to develop a rapid,simple and sensitive method for metolcarb determination.In this study,a novel imprinted quartz crystal microbalance(QCM)sensor for the detection of trace metolcarb was constructed.Metolcarb was used as the template,methacrylic acid(MAA)as the functional monomer and ethylene glycol dimethacrylate(EGDMA)as the crosslinking agent.The adsorption performance of the molecularly imprinted polymer(MIP)was evaluated by adsorption equilibrium binding experiment,adsorption kinetics experiment and Scatchard equation analysis.Then MIP was used as sensitive materials and immobilized on the surface of a quartz crystal gold electrode to construct a molecularly imprinted QCM sensor for metolcarb determination.The results showed that the MIP has high mass transfer velocity and adsorption capacity towards metolcarb.The maximum adsorption capacity is up to 4.93 mg g-1.Under the optimal conditions,the frequency shift increased linearly with the increasing concentration of target metolcarb in the range of 5 to 70 μg L-1,with a low detection limit of 2.309 μg L-1(S/N=3).The sensitive sensor exhibited good reproducibility and high selective recognition for metolcarb,and the selectivity coefficient of isoprocarb,propoxur,carbaryl were 2.45,2.97,4.41,respectively.The QCM sensor was applied for recognization and determination of trace metolcarb in apple juice,pears and cabbage at three concentration levels,the spiked recoveries was ranging from 85.4%to 95.5%(RSD<8.3%).Moreover,the results of QCM sensor has high consistency(correlation coefficient,0.9826)with the HPLC method,indicating that the method has good practicability.