Strategy For The Screening And Identification Of Unknown Halogenated Organic Compounds Based On Liquid Chromatography Tandem High Resolution Mass Spectrometry And The Application

Halogenated organic compounds are a large class of organic compounds containing halogen atoms,which are widely distributed in the natural environment.According to their effects,they can be divided into two kinds: halogenated organic pollutants and natural halogenated organic compounds.These halogenated organic compounds generated artificially came into the environment in large numbers,resulting in environmental pollution,that is,halogenated organic pollutants(HOPs).Most of HOPs have the property of persistent organic pollutants(POPs),which are one of the most concerned environmental pollutants in the field of environmental research.Except for these halogenated organic compounds generated artificially,there are numerous natural halogenated organic compounds in nature,which were once considered rare chemical strange objects,but in recent years the researches show that many natural halogenated organic compounds have unique biological activity,including anti-cancer,antiviral and antibacterial activities,which have great potential benefits for human beings.In the future,the identification of unknown halogenated organic compounds will become an important research field.Liquid Chromatography-High Resolution Mass Spectrometry(LC-HRMS)is one of the most important tools for the analysis and identification of organic compounds.The strategies for screening and identification of halogenated organic compounds based on LC-HRMS technology have also been reported,whereas they are only directed against a single type of halogenated organic matter,such as chlorinated or brominated or iodized organic compounds,without a systematic screening method.Therefore,in this study,we set up a systematic strategy for screening and identification of unknown halogenated(chlorinated,brominated and iodized)organic compounds based on LC-HRMS technology.Then,the strategy was applied to screening and identification of unknown halogenated disinfection by-products in tap water and unknown organic iodine compounds in seaweed iodine salt.The main research contents and results were as following:(1)A systematic screening strategy for unknown halogenated organic compounds including unknown chlorinated,brominated and iodinated organic compounds,has been established.The unknown chlorinated organic compounds are screened by filtered the blank background and using the isotopic abundances of chlorine atoms,while the brominated and iodized organic compounds are screened mainly by means of their characteristic fragment ions(Br-and I-)to trace the parent ions.(2)The screening method was used for the analysis of halogenated disinfection by-products in tap water of Wuhan City.With the optimized pretreatment conditions,127 halogenated disinfection by-products were successfully screened out.It includes 36 kinds of Cl-DBPs,65 kinds of Br-DBPs and 26 kinds of I-DBPs,of which 33 Cl-DBPs,50 Br-DBPs and 21 I-DBPs have not been reported.The change of halogenated disinfection by-products in tap water in Wuhan with time and region were examined.It is found that their content fluctuates to some extent with time and region.(3)In this study,the identification of unknown organic iodine compounds in seaweed iodized salt bought in the market was carried out using the screening method.A total of 38 organic iodine compounds and their transformation products(TPs)were identified successfully in seaweed iodine salt.Our experiments confirmed that the TPs were generated by the replacement of I atoms from organic iodine compounds with Cl atoms.Furthermore,the organic iodine compound contents in 4 seaweed iodine salt samples obtained from different manufacturers were measured,with significant differences in content being observed.