An optical instrument to test pesticide residues in agricultural products

摘要

Pesticide is one of the indispensability materials in modern agricultural management, however the excessive use of pesticides has threatened the ecological environment and people's health. This paper introduced an optical instrument to test the pesticide residues in agricultural products based on the inhibition rate of organophosphates against acrtyl-cholinesterase (AchE). The instrument consists mainly of a solid light source with 410nm wavelength, a sampling container, an optical sensor, a temperature sensor, and a MCU based data acquisition board. The light illuminated through the liquid in the sampling container, and the absorptivity was determined by the amount of the pesticide residues in the liquid. This paper involves the design of optical testing system, the data acquisition and calibration of the optical sensor, the design of microcontroller-based electrical board. Tests were done to reveal the affection of temperature and reacting time on AchE, to establish the relationship between the amount of methamidophos and dichlorvos with AchE. The results showed that the absorption rate was related to the pesticide residues and it could be concluded that the pesticide residues exceeded the normal level when the inhibition rate was over 50 percent. The instrument has potential application in vegetable markets.