Study Of The Assay Method For Organophosphorus Compounds

Recently, organophosphorus compounds (OPs) are one of uppermost ingredients to the contamination of the environment. They are widely used in modern agricultural, industry, medicine as pesticides or insecticides due to their broad-spectrum, easy degradation, high effectiveness and short half life in the environment, which contribute significantly to the economic benefits. Meanwhile, they also lead to a series of problems of environmental pollution and food contamination. A majority of OPs have strong toxicity, more toxic to human being and animals. Contacting with OPs and absorbing by skin, respiratory system and gastrointestinal tract lead to severe disease. With the high speed development of economy and the improvement of standard of living, the demand for people is not only for solving dress warmly and ear their fills but also for improving the character of life. Therefore, it is a hot spot that the public concern to the contamination of OPs. It becomes significantly to prevent and deal with the OPs pollution and food contamination, avoid acute comestible poisoning, improve the study of OPs analyses and detect pesticide residue duly and accurately. In recent years, there were some reports about the fast determination to OPs residue.Several established techniques exist for pesticide detection, which include spectroscopy, chromatography and mass spectrometry, in addition, enzyme inhibition, immunoassay and biochips technique etc current analytical techniques. These conventional methods are time-consuming and costly, and are hard to satisfy the increasing requirements of the scene detection; immunoassay analytical technique is both sensitive and easy to operate, but hard for preparation of antibody and only for determination singularity OPs. Comparatively, enzyme inhibition provide a simplicity, sensitivity, rapidness and economical instrument to detection OPs, moreover, it is adapt to a great many of samples filtration and locale inspect owing to needless good-sized and costly apparatus. Hereby, this article was based on enzyme inhibition principle and used spectrophotometry and electrochemistry to determine OPs residue. The content in detail and results are as follows:1. Study of 2,6-Dimethylbenzoquinone(2,6-DMBQ) as a new enzymatic spectrophotometric indicator for the assessment of the OPs.A new and alternative enzymatic spectrophotometric indicator,2,6-DMBQ was explored to assess the OPs impact on cholinesterase from duck blood. The principle of this method is measurement of the rate of production of thiocholine as the substrate acetylthiocholine (ATCh) is hydrolyzed by the ChE present in the sample. The produced thiocholine reacts with the 2,6-DMBQ and the enzymatic activity is assessed by measuring the absorbance decrease at 257 nm. The stability of 2,6-DMBQ, effect of pH and the concentration of components in enzymatic reaction were studied and optimized. It received good outcome for the system used for detecting rudimental OPs.The inhibition of ChE activity is increasing with the concentration of parathion methyl ranging from 0.01 to 100μg/mL.1μg/mL parathion methyl shows a about 30% ChE inhibition and 10μg/mL does a 58% inhibition, while 100μg/mL does nearly a 100% inhibition. It suggests that the present study contributes greatly to our future exploring 2,6-DMBQ as redox indicator for the development of electroanalytical method for ChE activity and electrochemical biosensors for OPs pollution.2. The study of effect mechanism of ionic liquid (ILS) with animal enzyme inhibitionThe influences of water-miscible ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]) on acetylcholinesterase (AChE) inhibition-based OPs compound assay was investigated. Some factors, such as the rudimental enzyme activity, the effect mechanism between [BMIM][BF4] and AChE, the inhibition time and detection limit, were evaluated in turn. As a result, the enzyme inhibition efficiency in 5.1%[BMIM][BF4]-phosphate buffer mixtures was increased by 3.1 times comparing with that in phosphate buffer solution (PBS). The residual enzyme activity decreased, while the inhibition degree by OPs increased due to the addition of [BMIM][BF4].3. A biomimetic AChE-liposome structure was constructed for the electrochemical determination of methyl parathion using square wave voltammetry.A biomimetic structure was constructed by reconstituting AChE into liposomes for the electrochemical determination of methyl parathion using square wave voltammetry. At the same time, some factors, for example the concentration of liposome and acetone, the time of enzyme reaction, and the time of AChE inhibition by methyl parathion were optimized one by one in the article. It is found the enzymatic activity and inhibition performance of reconstituted AChE is expected to be improved. Bioinspired AChE-liposome system shows the potential to provide a promising and sensitive medium in organophosphates assay with AChE.