Establishment On The Piezoelectric Immunosensor For Detection Of Methyl-Parathion

Methyl parathion is a kind of virulent organophosphorus pesticide, which has been forbidden in the use of vegetables and fruits, but is still an important routine detecting pollution in the agricultural products entrance trade and the supervision and detection for the food and environment safety. This article tried to develop a piezoelectric immunosensor for rapid and simple detection of methyl parathion through different detection methods, providing technical support for rapid and on the spot detection and supervision of pesticide residues in vegetables and fruits.The key point of developing the piezoelectric immunosensor is to immobilize the antibody onto the golden electrode of the quartz crystal, the article compared two immobilization methods, including protein A (SPA) and self immobilized membrane (SAMs) methods, the conclusion is: compared with SPA method, more antibody can be immobilized using SAMs method, as well as the stability, in condition that ion concentration is less than 20mmol/L, pH range is 7.0-7.4.Three methods have been studied when methyl parathion detected, including direct method, competitive method and enzyme catalyst aggregation amplifying method. For the direct method, the linearity scope of detecting methyl parathion is 1.0-25μg/mL, within which two concentration of methyl parathion has been retested for five times each, with the relative standard deviation of frequency 4.7%,5.3%, and detection limits 4.7%,5.3% respectively. The competitive method, which based on the competition between the OVA connective methyl parathion and the dissociative methyl parathion for the reaction of the antibody immobilized on the golden electrode of the quartz crystal, has a detection range of 0.1-10μg/mL, and the detection limit of 0.074μg/mL. Three concentration of methyl parathion within the detection range has been retested, the standard deviation of which are 5.944%,6.900%,9.517%(n=7). Added reclaimed test to the sample of tap water, soil and vegetables has heen studied with the reclaimed ratio of 90.7-101.1%,93.8-109.3%,71.9-96.1%. Enzyme catalyst aggregation amplifying method has been studied for detection of OVA connective methyl parathion. As the antibody, enzyme marked antibody, reactant and substrate added, the frequency reduced, which magnified the signal. The detection range of OVA connective methyl parathion is 0.1-4.5μg/mL.Three methods for detection methyl parathion have been studied, the immobilization method and the detection method have been compared, which eprovided the foundation for the further study of piezoelectric immunosensor for detection of multi-pesticide residues.