Study On Photoelectric Rapid Detection System Of Pesticide Residues

The application of pesticide promoted the development of agricultural industry and produced enormous economic benefit for humanity. Nevertheless, along with the increasing usage amount of pesticide, its harm exposed gradually, the main problem is the problem of pesticide residues in the food and environment. Even though the residues are finite, long touch of it will bring out great harm for our health. So how to control and detect effectively pesticide residues becomes a matter of great concern to us.The traditional pesticide residues detection method contains gas chromatography, high performance liquid chromatography, combined gas chromatography mass spectrometry, high performance liquid chromatography mass spectrometry, and so on. Though these methods are precise, there is a lot of disadvantage in these methods such as fussy sample preparation, large consumption of reagent and long elapsed time. And it can not satisfy the requirement of rapid and green detection. Photoelectric detection technology has advantage of high sensitivity, little sample, rapid and simple, and able to run online and continuously in the severe environment. Its application in pesticide residues detection has attracted considerable interest. Combining chemiluminescence method with photoelectric detection principle, this paper designed a photoelectric detection system to detect the pesticide residues, and conduct a study of theory and experiment.In this paper, firstly, it is discussed theoretically on composition of photoelectric detection system, parameter characteristics of photoelectric detector, generation mechanism of noise and selecting principle of device. The designed photoelectric detection system is mainly made up of several parts: photoelectric detector, Pre-amplification circuit, Active filter circuit, main amplifying circuit, A/D converter circuit and single chip. Through analyzing and comparing the characteristics of photoelectric detectors, this paper determined the optimum photoelectric detector. And this paper analyzed theoretically several noises existing in the circuit and how to control it. The system mainly designed Pre-amplification circuit, Active filter circuit and main amplifying circuit. For A/D converter and single chip, this paper selected their models and designed the circuits.Detect the Dipterex through the designed photoelectric detection system. The result showed that the lowest detectable limit was 0.08mg/L, below the national standard O.lmg/L. Set up the mathematical model of luminous intensity (voltage) and density, achieve the error analysis of pesticide residues, and further revise the circuit parameter of the photoelectric detection system. The experiment showed that the system could achieve the photoelectric detection of pesticide residues, after the further study, it could be used to test whether the pesticide residues are out of limits or not.