Preparation Of Nicosulfuron And Ametryn Molecularly Imprinted SPR Sensors And Their Analytical Application

Molecular imprinting is a method that can prepare polymer material with predetermined selectivity towords a certain guest molecule. This technique derives from Fischer’s lock-and-key hypothesis and Pauling’s antibody-forming hypothesis initially. The preparation of molecularly imprinted polymer has not only the specific recognition ability of enzymes and antibodies, but also the unique physical and chemical stability, long service life, simple preparation methods, resist acid, alkali, hot, organic solvents and other environmental factors influence etc, and the technology has been widely used in high performance liquid chromatography (HPLC), solid phase extraction, membrane separation technology, chiral isomers separation, etc.Surface plasmon resonance (SPR) is a physical optical phenomenon which produced by using metal film optical coupling. Monitoring the change of SPR can achieve fast and real-time monitoring of the interaction between the molecules, without mark samples and sample requirement is few. In the process of the testing, it is convenient and quick to detect the samples and the sensetivity is very high; Application range is very wide; In most cases, sample pretreatment is omitted; It is even easy to detect the chemical material in the opacity and opaque samples. SPR sensor is widely used in recent years.In this thesis, by combining the good performance of MIT such as high selectivity and good recognition with the high sensitivity and good response performance of SPR spectroscopy, we developed molecularly imprinted SPR sensors for nicosulfuron and ametryn.Based on photo-radical polymerization, the nicosulfuron-imprinted SPR sensor was prepared. The effect of pH value on the adsorption of the imprinted membrane to the analyte was investigated. Meanwhile, we also evaluated the properties of its adsorptivity and selectivity at the optimal pH. Compared to the non-imprinted polymer, the imprinted polymer showed higher adsorption efficiency for nicosulfuron than that of other structurally related analogues. The method showed good linearity between5.0-25×10-1mol/L. The association constant of the imprinted sites in the composite to nicosulfuron (Kass) was calculated to be1.6x1010L/mol and the change in Gibb’s free energy was-58.148kJ/mol. The results indicated that the developed SPR sensor for the detection of nicosulfuro had the advantages such as simplicity, high-speed, high sensitivity and good recovery and when it was used to determine the nicosulfuron herbicide in the tap water and soil, based on a signal to noise ratio of3, the detection limits were5.62x10-14mol/L and1.01×10-13mol/L, the mean recoveries were85.6%and76.6%, the relative standard deviations (RSD) obtained were1.8%and3.2%for the tap water and soil, respectively.Based on surface-initiated atom transfer radical polymerization (ATRP), the ametryn-imprinted SPR sensor was prepared. Under the optimized experimental conditions, the SPR sensor had higher response for the template ametryn. Based on a signal to noise ratio of3, the detection limits of ametryn were3.51×10-8mol/L and6.19×10-8mol/L for the soybean and white rice, respectively. The method showed good recoveries and precision for the soybean and white rice samples spiked with ametryn. This suggests that a combination of SPR sensing with MIP film is a promising alternative method for detection of ametryn.