Development And Application Of A Wheat-Esterase Paper For Determining Pesticide Residues

Many biological and chemical methods are used to determine Organophosphoruspesticides residues in fruits and vegetables, such as Chromatograpy, Spectrometry,Enzyme Inhibition, Immunoassay and Chemical luminary and so on. But enzymeinhibition is playing very important role in determining process, because of advantagesof rapidness, simplicity and higher sensitivity. According to the principle of Enzymeinhibition, this experiment compared advantages between these two substrates, andpurified wheat esterase with the method of Ion Exchange Chromatography, and tried todevelop rapid test paper. Besides, it also explained and discussed many questions whichwere found in the process of using rapid test paper. The results were described asbellow:1.2,6-dichloro-benzennone-Indopheny-lacetate and fast blue B salt are two kinds ofcommon substrates in Enzyme inhibition, both of which could product coloring reactionat the function of wheat esterase. But, the result confirmed that2,6-dichloro-benzenone-indopheny-lacetate is better used as substrates than fast blue Bsalt, the main advantages include: Firstly, substrate and product have finer stability;Secondly, the reaction condition of wheat esterase is more optional and reasonable, themost optimal temperature and pH are 35℃and 7.0 respectively, so it is easy to controlreaction condition. Thirdly, Correlation coefficient from regression equations reflects theaccuracy of the method. Finally, higher recovery rate with the method of addingpesticide, it reflected that the method with 2,6-dichloro-benzennone-indopheny-lacetateas its substrate has lower limit of detection.2. Enzyme activity is one of the most key factors which are related with sensitivityand stability of methods. The article purified wheat esterase with the method ofDEAE-52 Ion Exchange Chromatography. The result showed the protein content ofpurified esterase was 2.86 more than primary esterase. Moreover, the activity of esterase was improved by purification.3. This experiment used the method of immersing and vacuum dehydrating at lowertemperature to develop rapid test paper. The result reflected that the sensitivity of paperwas low, maybe because the activity of enzyme is too low, or lots of enzyme was loss inthe process of making. Therefore, it is need to search for newer ways to improve enzymeactivity and better scheme to develop rapid test paper.