The Fast Detection Technology Of Organophosphorus And Carbamate Pesticides Residue By Immobilized-esterase And The Application Research

Same animal cbolinesterase, plant esterase ran also be inhibited by organophosphorus and carbamate pesticides. Plant-esterase can hydrolyze 1-Naphthyl acetate into naphthol and acetic acid . A color reaction can take place between naphthol and Fast Blue B and magenta will be seen. When the plant-esterase was inhibited by pesticides the color reaction can't happen.In the research we use plant esterase substitute animal cholinesterase, the planr-esterase can be extracted from wheat flour which is selled in market. Take 25 ml. distilled water into 5g wheat flour and shake 30min on a mechanical shaker and then centrifuge 20min at 5000rpm. The upper liquid layer was filtrated and conserved in a 4 C refrigerator. Before use, the slock solution will be diluted by phosphate buffer. Take 20p. L diluted stock esterase solution to a micro hole on a polystyrene sheet. When the phosphate buffer was evaporated the micro-hole will be rinsed 3 time by distilled water. Put the sheet in ambient temperature, when the water drying put the sheet in a desiccator in a dark ambient. We call the micro-hole polystyrene sheet as pesticides detector.Fortify distilled water with appropriate amount of pesticides into 1000ppb, 100ppb, 10ppb, 1ppb fortification solution respectively. An inhibition experiment was taken by the fortification solution and the result was recorded. The sensitivity in water was 10-100ppb.Fortify cabbage and apple with appropriate amount of pesticides into 1ppm,0.5ppm, 0.1ppm respectively and extract with 20% methanol. Then an inhibition experiment was taken by the 20% methanol extracting solution and the result was recorded. The detection limit in cabbage and apple was 0.1-1.0ppm.A pesticides residue detecting kit include pesticides detector, substrate, developer et al. Compared with other methods the kit have 3 differences: first, the kit use plant-esterase substitute the AchE or BuchE; Second, The kit use immobilized-esterase, other methods all use liquid esterase. Third, the kit use 20% methanol as the extract while others use phosphate buffer or water, the extract efficiency was improved.The kit only use to detect organophosphorus and carbamate pesticides. The result is the summation of the two pesticides. It doesn' t suggestion there is no pesticides in the sample when the result is negative. Maybe , the content is below the detect limit.