Direct Mass Spectrometry For Analysis Of Volatile Organic Compounds Through Water Radical Cations

Volatile organic compounds（VOCs）are widely present in human production and life,and play a vital role in chemistry,materials,medicine,environment and food.The content,structure and other differences of VOCs are closely related to their properties and biological functions.Therefore,rapid and direct analysis of VOCs is of great significance.The common analytical methods for analyzing VOCs contain gas chromatography-mass spectrometry（GC-MS）,select ion flow tube mass spectrometry（SIFT-MS）,and proton transfer reaction mass spectrometry（PTR-MS）.However,GC-MS methods usually require complex sample pretreatment,cumbersome operations,large sample consumption,time-consuming and laborious.SIFT-MS and PTR-MS methods can avoid deficiencies in GC-MS methods but require complex experimental devices.The use of derivatization reagents in experiments may also have contamination or post-treatment problems,which are difficult to meet the requirements of simple,sensitive,rapid and accurate analysis of actual samples.In this paper,ambient corona discharge ionization mass spectrometry was used to obtain high abundance,green and easily available water radical cations.A novel method based on water radical cations was developed for the real-time,in-situ,accurate,sensitive,and rapid analysis of VOCs in exhaled human breath and VOCs in red wine.The main research contents of this paper are as follows:1.The sources and main functions of VOCs and their harm to ecological environment and human were briefly summarized.The principle of mass spectrometry and classic ionization technologies were introduced,and the main analysis methods and their shortcomings of VOCs in samples were summarized.2.The significance of preparing water radical cations,the current research status of water radical cations,methods and devices for rapidly preparing large amounts of water radical cations under ambient condition were introduced.This will provide technical support for chemical research related to water radical cations.3.A new ambient corona discharge ionization mass spectrometry method for the rapid in-situ analysis of hexenols and carbon-carbon double bond isomers using water radical cations as the primary reagent ion was established.The high-abundance water radical cations as primary reagent ions were prepared by ambient corona discharge ionization.An ambient corona discharge ionization mass spectrometry platform was established for the reaction between hexenol isomers and water radical cations by regulating the energy transfer to make them collided with each other in a three-dimensional space to form epoxidized products.The structural identification of hexenol compounds was achieved by diagnostic ions from epoxidized products,which were generated by tandem mass spectrometry and could be used to locate carbon-carbon double bond positions.The established analytical method was applied to rapidly detect hexenol isomers in red wine with satisfactory results.The method has the advantages of low sample consumption,rapid derivatization,simple operation as well as easy spectral solution,which has potential application value in the study of the structure identification of carbon-carbon double bond compounds.4.Based on the strategy of water radical cations as the primary reagent ions,a method for real-time and rapid detection of acetone in human exhaled breath was established by ambient corona discharge ionization mass spectrometry.A real-time online analysis platform was built for the interaction of water radical cations and exhaled breath.Ambient corona discharge ionization mass spectrometry technology was used to prepare water radical cations interacted with acetone in the exhaled breath samples to form product ions[M+H2O]^+·,which achieve rapid analysis of acetone in the exhaled breath of the human body.Under the optimal experimental conditions,the method was used to monitor the acetone in the volunteers’exhaled breath.Combining with the chemometric method,the identification model of smoking volunteers and non-smoking volunteers was established.The established method has the advantages of low sample consumption,fast analysis and simple device,which is expected to be used widely in clinical diagnosis and treatment research based on exhaled breath analysis.