Studies On Piezoelectric Immunosensor And Soil Bound Residues Of Metsulfuron Methy1

A piezoelectric (Pz) czystal immunobiosensor for the determination of metsulfuron-methyl (MS) herbicide has been developed. MS antibodis (polyclonal from rabbit) were coated onto the gold electrode of 10MHz piezoelectric crystals, which were precoated with y aminopropyltriethoxy-silane (APTES) and protein-A successively. Detections ranging from 0.03100 ii g/l (ppb) of MS herbicide in water could be achieved. The cross reaction tests showed that the Pz biosensor assays would not be influenced by ions, surfactant, organic solvents and most of sulfonylurea herbicides with similar molecular structures like bensulfuron and so on in water. However, some of sulfonylurea herbicides with methoxycarbonyl phenylsulfonamide group could be recognized by this biosensor. The Pz biosensor could be regenerated to reuse for about thirty assays.Five different methods used for immobilizing the MS antibodis onto the electrode of piezoelectric crystal were compared. The ways to keep the activity of antibodis in the abtibody immobilization were discussed. The reactivity of the immobilized antibodis with the free antigen (MS) was analyzed via an optimal model of Langumuir. It was suggested that the constant K of the antibody affinity might be a primary factor that significantly affects the detection limit and the sensitivity of the immunobiosensor assay. The features of the immunobiosensors and the ELISA methods were also compared in this research.The bound residues of MS in two typical soils, brown and black soils, in north china and their bioavailability to corn were studied with a double ?C-labeled MS tracer. The results showed that the ratio of bound residues of MS in the black soil and brown soil are 36.7% and 35.7% respectively after incubated for about a single wheat growth period in laboratory condition. The bound residues of ?C-labeled MS and degradation products were mainly distributed in Fulic acids in the soils. The microbes in the soils could affect the forming of bound residues significantly. The bound residues were bioavailable to maize. Its?concentrations to inhibit the 50% growth of maize were 25.0 ug/kg and 21.5 ug/kg respectively for brown and black soils.