Study On Proton Transfer Reaction Mass Spectrometry Detection Method For Desorption Injection And Rapid Chromatographic Separation Of Organic Compounds

Proton-transfer-reaction mass spectrometry(PTR-MS)is an on-line detection technique suitable for volatile organic compounds,which offers advantages such as low detection limits,high sensitivity,and short response times.However,conventional PTR-MS relies solely on one-dimensional qualitative analysis based on mass-to-charge ratio,and therefore cannot distinguish between isomers.Moreover,the sampling technique has limitations on the detection of organic molecules in solid samples.In this thesis,the fast-gas chromatography proton-transfer-reaction mass spectrometry(FGC-PTR-MS)is developed on the PTR-MS apparatus,and has two functions of syringe injection and thermal/laser desorption injection.FGC-PTR-MS enhances the qualitative capability by distinguishing isomers,while the thermal/laser desorption injection capability enables the analysis of organic compounds in solid samples.The primary research findings comprise:1.The development of fast-gas-chromatography proton-transfer-reaction mass spectrometry.We combine the separation ability of fast-gas-chromatography(FGC)and the on-line detection ability of PTR-MS to build the syringe injection FGC-PTRMS device.To create a split-free connection between the FGC and PTR-MS,a capillary chromatographic column with the right length and inner diameter was chosen,and the column output was then linked to the drift tube in the PTR-MS.Rapid separation detection of diverse isomers was made possible through column temperature optimization.The retention times of several volatile organic chemicals(methanol,ethanol,acetone,acetonitrile,benzene,toluene,ethylbenzene,o-xylene,m-xylene,and p-xylene)were less than 3.5 minutes,and the separation degrees between butanol isomers were all over 1.5,accomplishing complete separation.After analyzing the volatile organic compounds in brand D latex paint qualitatively and quantitatively,we find that the tert-butanol and n-butanol can be distinguished qualitatively well,and that the amount of toxic tert-butanol is 4.41 ppm,which is below the indoor air safety standard value.(100 ppm).Additionally,the valeramide reagent was examined for impurities using FGC-PTR-MS,and it was discovered that it had at least two volatile organic impurities.The findings demonstrate that FGC-PTR-MS can realize the quickly qualitative and quantitative analysis of volatile organic compounds,which provides the experimental basis for the development of related mass spectrometry combined instrument.2.The development of thermal-desorption-injection fast-gas-chromatography proton-transfer-reaction mass spectrometry.The technique of TDI-FGC-PTR-MS was developed by combining thermal-desorption-injection(TDI)with FGC-PTR-MS.In order to enable quickly desorption injection and detection of volatile organic compounds in solid samples,the rate of release of volatile substances is increased by heating and raising the temperature of the solid sample.These substances are then put into the FGC-PTR-MS system.To achieve precise measurement,this method is also used with the quantitative mass release rate.Acetaldehyde,methanol,ethanol,acetone,and glycolaldehyde dimer are the principal residual substances,according to the results of the TDI-FGC-PTR-MS method used to detect residual solvents in three kinds of cephalosporin solid tablets.The mass release model showed that their residues were all less than 1.2mg/g.The TDI-FGC-PTR-MS approach uses less time and does not require solvent extraction compared to the gas chromatography with flame ionization detection method.Therefore,the TDI-FGC-PTR-MS detection technology developed by us can realize the quickly detection and analysis of volatile organic compounds in solid samples.3.The development of laser-desorption-injection fast-gas-chromatography proton-transfer-reaction mass spectrometry.The technique of LDI-FGC-PTR-MS was developed by combining laser-desorption-injection(LDI)with FGC-PTR-MS.By performing mid-infrared wavelength laser desorption on solid samples,organic compounds can be vaporized and introduced into FGC-PTR-MS to realize quickly desorption injection and analysis of non-volatile organic compounds in solid samples.To increase the effectiveness of gasification and extraction,laser energy was first optimized using phenol,carrots,and cefuroxime axetil tablets.Afterwards,LDI-FGCPTR-MS was used for the detection and analysis of pesticide active ingredients,simulated food residues,common commercial pesticides,soil and chemical products.The transfluthrin was used to compute the detection limit for LDI-FGC-PTR-MS,and the results showed a limit of about 3 pg.These preliminary experiments show that nonvolatile organic molecules may be quickly desorption injection and detected in solid samples using the established LDI-FGC-PTR-MS technology,broadening the range of PTR-MS applications.In conclusion,the development of the desorption-injection fast-gaschromatography proton-transfer-reaction mass spectrometry technology in this thesis can achieve the efficient desorption injection and analysis of volatile and non-volatile organic compounds in a solid samples,enhances the detection performance of PTR-MS and expands the application range.Additionally,the separation capability of FGC was incorporated to create a two-dimensional qualitative technique that depends on retention time and mass-to-charge ratio in order to address the shortcomings of depending primarily on the one-dimensional qualitative method of mass-to-charge ratio in PTR-MS.This strategy shows notable qualitative analytical improvements.And FGC-PTR-MS can detect and analyze organics in solid samples by thermal desorption/laser desorption.