@article {2784,
	title = {Direct detection of benzene, toluene, and ethylbenzene at trace levels in ambient air by atmospheric pressure chemical ionization using a handheld mass spectrometer.},
	journal = {Journal of the American Society for Mass Spectrometry},
	volume = {21},
	year = {2010},
	month = {2010 Jan},
	pages = {132-5},
	abstract = {<p>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{\textquoteright} 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.</p>
},
	keywords = {Air, Atmospheric Pressure, Benzene, Benzene Derivatives, Equipment Design, Ions, Limit of Detection, Mass Spectrometry, Toluene},
	issn = {1879-1123},
	doi = {10.1364/AO.50.001792},
	author = {Huang, Guangming and Gao, Liang and Duncan, Jason and Harper, Jason D and Sanders, Nathaniel L and Ouyang, Zheng and Cooks, R Graham}
}
@article {2802,
	title = {Design and characterization of a multisource hand-held tandem mass spectrometer.},
	journal = {Analytical Chemistry},
	volume = {80},
	year = {2008},
	month = {2008 Oct 1},
	pages = {7198-205},
	abstract = {<p>A wireless-controlled miniature rectilinear ion trap mass spectrometer system, total weight with batteries 5.0 kg, consuming less than 35 W of power, and having dimensions of 22 cm in length by 12 cm in width by 18 cm in height, is characterized. The design and construction of the mass spectrometer including mass analyzer, vacuum system, electronics system, and data acquisition and processing systems, is detailed. The mass spectrometer is compatible with various types of ionization sources including a glow discharge electron impact ionization source used in the internal ionization mode, and various atmospheric pressure ionization sources, including electrospray ionization, atmospheric pressure chemical ionization, and desorption electrospray ionization, which are employed for external, atmospheric pressure ionization. These external sources are coupled to the miniature mass spectrometer via a capillary interface that is operated in a discontinuous fashion (discontinuous atmospheric pressure interface) to maximize ion transport. The performance of the mass spectrometer for large and small molecules is characterized. Limits of detection in the parts-per-billion range were obtained for selected compounds examined using both the internal ionization and external ionization modes. Tandem mass spectrometry and fast in situ analysis capabilities are also demonstrated using a variety of compounds and ionization sources. Protein molecules are analyzed as the multiply protonated molecules with mass/charge ratios up to 1500 Da/charge.</p>
},
	keywords = {Miniaturization, Sensitivity and Specificity, Tandem Mass Spectrometry},
	issn = {1520-6882},
	doi = {10.1364/AO.50.001792},
	author = {Gao, Liang and Sugiarto, Andy and Harper, Jason D and Cooks, R Graham and Ouyang, Zheng}
}
