Methodologies On The Detection Of Nerve Agents

Nerve agent is a kind of organophosphonate compounds. The extremely acute toxicity of nerve agents is executed by their inhibitions on cholinesterase. Phosphylation of serine in active site of the enzyme results in loss of cholinesterase activity, and accumulation of acetylcholine, ubiquitous cholinergic over-stimulation and disorders of numerous body functions can be followed. Hence, rapid, reliable and sensitive methods for detection of exposures to nerve agents have been paid great attention and thus developed, especially since the Chemical Weapons Convention (CWC) has been validated in 1997, these methods would also be further helpful for better handling of CWAs.The current methods for detecting nerve agents and their related compounds should meet both the needs of laboratory identification and on-site detection. The environmental and biomedical samples are all included in the analytical fields of laboratory identification, and the latter attracts more concern due that the analysis of biomedical samples can provide undoubted evidence of some certain exposures to nerve agents. Meanwhile, the on-site detection is mainly aimed at high-speed and high-sensitive detection for environmental samples and exploiting new detection methods for nerve agents and their related compounds. Considering the above mentioned aspects, the thesis consists of three chapters:Chapter I summarized the current methods for detection of nerve agents and their related compounds in biomedical samples, as well as the new sensing methods for nerve agent detection. The objective and the content of the thesis were followed.Chapter II established a fluoride ion reactivation - gas chromatography-mass spectrometry method for determining sarin exposures in human serum. The reaction and extraction conditions were systematically investigated and optimized to regenerate a maximum amount of sarin. The highest reactivation efficiency was 86%, which was calculated from the recovery of butyrylcholinesterase activity. For regenerated sarin over the inhibition of butyrylcholinesterase activity, the linear calibration curve was ranged from 6% to 85% and the limit of detection(LOD) was 4%. No interference of human serum sample was found in this simple method. It can be used as an ideal method for the retrospective detection of sarin exposures.Chapter III developed a simple and high sensitive strategy for high toxic organophosphates direct detection, which based on an Acetylcholinesterase(AChE)/TGA-CdS nanocrystals(NCs) hybrid system. The luminescent response of this assay can be traced by the change of interaction between substrates for AChE biocatalytic reaction and surface-state luminescent thioglycolic acid-CdS NCs without the need for NC bioconjugation. The LOD of the method can be achieved as a 10-10 M level. This chapter not only described a novel approach for organophosphonate compounds detection but also provided a new direction for the application of biomacromolecule-nanocrystals.