Objective This study analyzed the chemical structures of two unknown substances in e-liquid using methods such as nuclear magnetic resonance(NMR),infrared spectroscopy(IR),and mass spectrometry(MS).Methods After separating,purifying,and freeze-drying two suspicious substances from e-liquid,GC-MS analysis was used to obtain the mass spectrum characteristic ion fragments and fragmentation patterns of unknown compounds.The precise mass numbers were measured by high-resolution mass spectrometry,and proton numbers and their assignments,carbon types,and fluorine atom numbers and positions were obtained by combining 1HNMR,13CNMR,and 19FNMR.The functional groups were then analyzed by infrared spectroscopy.Results Through data analysis,the molecular formulas of the two suspicious substances are C13H13FN2O2 and C14H15FN2O2,respectively.Their structures were determined to be etomidate derivatives:1-(o-fluoromethylphenyl)imidazole-5-carboxylic acid methyl ester and 1-(o-fluoromethylphenyl)imidazole-5-carboxylic acid ethyl ester.Conclusion The structural data of two substances obtained in this study in terms of mass spectrometry,nuclear magnetic resonance,and infrared spectroscopy provide support for combating crimes involving the two substances,and provide reference for the regulation and detection of the two drugs.

Objective This study analyzed the chemical structures of two unknown substances in e-liquid using methods such as nuclear magnetic resonance(NMR),infrared spectroscopy(IR),and mass spectrometry(MS).Methods After separating,purifying,and freeze-drying two suspicious substances from e-liquid,GC-MS analysis was used to obtain the mass spectrum characteristic ion fragments and fragmentation patterns of unknown compounds.The precise mass numbers were measured by high-resolution mass spectrometry,and proton numbers and their assignments,carbon types,and fluorine atom numbers and positions were obtained by combining 1HNMR,13CNMR,and 19FNMR.The functional groups were then analyzed by infrared spectroscopy.Results Through data analysis,the molecular formulas of the two suspicious substances are C13H13FN2O2 and C14H15FN2O2,respectively.Their structures were determined to be etomidate derivatives:1-(o-fluoromethylphenyl)imidazole-5-carboxylic acid methyl ester and 1-(o-fluoromethylphenyl)imidazole-5-carboxylic acid ethyl ester.Conclusion The structural data of two substances obtained in this study in terms of mass spectrometry,nuclear magnetic resonance,and infrared spectroscopy provide support for combating crimes involving the two substances,and provide reference for the regulation and detection of the two drugs.