title: Direct detection of benzene, toluene, and ethylbenzene at trace levels in ambient air by atmospheric pressure chemical ionization using a handheld mass spectrometer.
abstract: The capabilities of a portable mass spectrometer for real-time monitoring of trace levels of benzene, toluene, and ethylbenzene in air are illustrated. An atmospheric pressure interface was built to implement atmospheric pressure chemical ionization for direct analysis of gas-phase samples on a previously described miniature mass spectrometer (Gao et al. Anal. Chem.2006, 78, 5994-6002). Linear dynamic ranges, limits of detection and other analytical figures of merit were evaluated: for benzene, a limit of detection of 0.2 parts-per-billion was achieved for air samples without any sample preconcentration. The corresponding limits of detection for toluene and ethylbenzene were 0.5 parts-per-billion and 0.7 parts-per-billion, respectively. These detection limits are well below the compounds' permissible exposure levels, even in the presence of added complex mixtures of organics at levels exceeding the parts-per-million level. The linear dynamic ranges of benzene, toluene, and ethylbenzene are limited to approximately two orders of magnitude by saturation of the detection electronics.
authors.affiliation: Department of Chemistry and Center for Analytical Instrumentation Development, Purdue University, West Lafayette, Indiana, USA.
authors.forename: Guangming
authors.initials: G
authors.lastname: Huang
authors.forename: Liang
authors.initials: L
authors.lastname: Gao
authors.forename: Jason
authors.initials: J
authors.lastname: Duncan
authors.forename: Jason D
authors.initials: JD
authors.lastname: Harper
authors.forename: Nathaniel L
authors.initials: NL
authors.lastname: Sanders
authors.forename: Zheng
authors.initials: Z
authors.lastname: Ouyang
authors.forename: R Graham
authors.initials: RG
authors.lastname: Cooks
mesh_terms: D000388:Air / Q000032:analysis*; D001274:Atmospheric Pressure; D001554:Benzene / Q000032:analysis*; D001555:Benzene Derivatives / Q000032:analysis*; D004867:Equipment Design; D007477:Ions / Q000737:chemistry; D057230:Limit of Detection; D013058:Mass Spectrometry / Q000295:instrumentation* / Q000379:methods*; D014050:Toluene / Q000032:analysis*
chemical_list: D001555:Benzene Derivatives; D007477:Ions; D014050:Toluene; D001554:Benzene; C004912:ethylbenzene