The Research On Detection Method Of Chemical Warfare Agents And Hydrolysis Products In Water By Microextraction By Packed Sorbent-mass Spectrometry

The production,storage and use of chemical warfare agents have brought major problems to the country and public safety.The rapid and accurate extraction of chemical warfare agents is the basic requirement of chemical defense reconnaissance.Therefore,sample preparation with chemical warfare agents and hydrolysis products as the target is carried out.Methodological research is also a key direction in the field of chemical defense and counter-terrorism.In recent years,sample preparation technology has developed rapidly,and related research has continued to deepen in the direction of miniaturization,convenience,automation,and environmental protection.The Microextraction by Packed Sorbent（MEPS）technology is based on the principle of solid phase extraction.It is improved to a more convenient extraction method on the basis of solid phase extraction.It has the advantages of fast,efficient,green and other advantages.It has been widely used in many fields such as clinical drug analysis,food safety and environmental monitoring,but the MEPS method for chemical warfare agents has not been reported.This study combined MEPS with gas chromatography-mass spectrometry to successfully establish a MEPS-GC-MS method,which realized the rapid detection of organophosphate,sarin,soman,and sarin hydrolysis products methylphosphonic acid and isopropyl methylphosphonate in water.At the same time,without derivatization,the MEPS and Nano-ESI-MS were combined to establish the MEPS-Nano-ESI-MS method and successfully applied to the determination of methylphosphonic acid and isopropyl methylphosphonate.The target was extended to mustard gas hydrolysis products,the MEPS-Nano-ESI-MS method was established and combined with stoichiometry to realize the rapid and sensitive detection of mustard gas hydrolysis products thiodiglycol.The main progresses were as follows:1.Establishment of MEPS-GC-MS method for the detection of organoph osphate,sarin and soman（1）With trimethyl phosphate,triethyl phosphate,tripropyl phosphate and diethyl methyl phosphate as target compounds,a MEPS-GC-MS method was established and eight factors affecting extraction efficiency were optimized in detail.When using the extraction-discard mode of sample loading,C₁₈ is the sorbent,the sample volume is1000μL（the sample volume is 100μL per cycle,and the sample is loaded 10 times continuously）,the sample circulation speed of 5μL/s,The best extraction effect can be obtained when chloroform（30μL）is the elution solvent and the elution rate is 5μL/s（4cycles）.The entire extraction process can be completed in only 8 minutes.The method had been validated and the detection limits of trimethyl phosphate,triethyl phosphate,tripropyl phosphate,and diethyl methyl phosphate are 10 ng/m L,5 ng/m L,1 ng/m L and5 ng/m L,respectively.The matrix effect existing in the two actual water samples of tap water and groundwater was evaluated.The calculated matrix factor ranged from 0.8 to1.3,indicating that the matrix effect can be ignored,and the relative relative standard deviation（RSD）≤4.5%,the organic elution step used The solvent is only 30μL,which meets the development requirements of green chemistry.（2）With sarin and soman as the target compounds,the MEPS-GC-MS method was established and optimized for the four main influencing factors in the extraction process.The results showed that C₁₈ was used as the adsorbent and the 1000μL sample was converted to 5μL/s,the elution solvent is 50μL ultrapure water,and the elution step selects 40μL chloroform for 5 cycles to obtain the best extraction effect.The method has been validated and the detection limit of sarin and soman is 1～2 ng/m L.The matrix effect existing in the two actual water samples of tap water and rainwater is evaluated,and the results obtained by calculating the matrix factor range from 0.8 to 1.1.The results showed that the matrix effect can be ignored,RSD≤8.0%.At the same time,the feasibility of using the established pre-processing method in the field was explored.Simulating field test conditions,the experimental results showed that the established MEPS method could quickly extract the organophosphorus toxic agent in water,and it could be effectively stored for more than 3 days,which effectively solved the problem that sarin could not be determined at any time due to rapid hydrolysis in a short period of time.2.The extraction and detection of sarin hydrolysis products by MEPS-MSWhen the nerve agents has been hydrolyzed,the existence of its original bo dy cannot be detected,so its hydrolyzed product is also an important evidence t o confirm whether the water body is contaminated by the nerve agents.（1）A new water-resistant derivatization reagent 1-（diazomethyl）-3,5-bis（triflu oromethyl）benzene was synthesized,and the reagent’s on-site storage convenience and whether it is suitable for in-situ detection of hydrolysis products by GC-M S instrument From the perspective of step method,it is compared with bis（trimet hylsilyl）trifluoroacetamide（BSTFA）and trimethylphenylhydroxide（PTMAH）amm onium.The results show that the injection port pyrolytic methylation reaction Th e required time is short,the reagents are easy to store,and it is more on-site op erability.The MEPS（PTMAH）-GC-MS method was established to detect the pre sence of isopropyl methylphosphonate in water bodies,and it was verified that it can effectively extract isopropyl methylphosphonate in water bodies in a short ti me.（2）The MEPS-Nano-ESI-MS method was established using methylphosphonic acid and isopropyl methylphosphonate,which are hydrolysis products of sarin,as the target analytes.Two factors,namely the type of adsorbent and the type of elution solvent,were optimized for the influencing factors in the extraction process.It shows that using graphitized carbon black as the adsorbent and methanol/water（v/v,1:1）as the eluting solvent can obtain the best extraction effect.The detection sensitivity of the two target methods is 1ng/m L,and the matrix effect existing in the two actual water samples of tap water and rainwater is evaluated.The calculated matrix factor results range from1.1 to 9.7,and both matrices have enhanced effects,RSD≤7.4%.This method can quickly verify the contamination of chemical agents on site by extraction and analysis of poisoned water samples without chromatographic separation and derivatization.3.MEPS-Nano-ESI-MS method for detection of hydrolysis products of mustardThe MEPS-Nano-ESI-MS method was established for the extraction and detection of thiodiglycol,a hydrolysis products of mustard gas.At the same time,graphene quantum dot functionalized nanomaterials were synthesized and filled in self-made MEPS equipment as adsorbents.The synthesized materials were compared with a variety of commercial adsorbent materials such as C₁₈ in terms of adsorption effect.The results showed that graphene quantum dots The functionalized material shows better adsorption performance for thiodiglycol.Single factor rotation test（OFAT）and central composite design（CCD）methods were used to optimize and evaluate the influence of influencing factors on extraction efficiency.Under the optimal measurement conditions,the established method has a lower detection limit（1 ng/m L）and an extraction detection time of only 5 min.The matrix effect existing in two actual water samples of tap water and rainwater is evaluated and calculated The matrix factor results are all 1.0,indicating that the matrix effect can be ignored,and the RSD is 5.4%.The method only requires a small amount of organic solvents and sample volume,and extraction and detection can be completed within 5 minutes,confirming that MEPS-Nano-ESI-MS is a suitable method for the determination of mustard gas hydrolysis products in aquatic environment.