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Rapid Commun Mass Spectrom

Title:		Design of a low-temperature plasma (LTP) probe with adjustable output temperature and variable beam diameter for the direct detection of organic molecules
Author(s):		Martinez-Jarquin S; Winkler R;
Address:		"CINVESTAV Unidad Irapuato, Department of Biotechnology and Biochemistry, Km. 9.6 Libramiento Norte Carr. Irapuato-Leon, 36821 Irapuato Gto., Mexico"
Journal Title:		Rapid Commun Mass Spectrom
Year:		2013
Volume:		27
Issue:		5
Page Number:		629 - 634
DOI:		10.1002/rcm.6494
ISSN/ISBN:		1097-0231 (Electronic) 0951-4198 (Linking)
Abstract:		"RATIONALE: The direct detection of organic molecules by mass spectrometry requires ionization methods which are compatible with ambient conditions. A relatively new strategy is the use of a free low-temperature plasma beam for ionization. The objective is to design a safe and adjustable plasma beam to enable optimal ionization and desorption parameters for specific molecules. METHODS: A plasma probe based on a dielectric barrier discharge was designed, where the plasma is guided through an internal second tube. This setup permits different beam diameter settings and the control of the plasma temperature. The ionization and desorption of pure organic compounds, as well as their direct detection from roasted coffee beans, were tested. RESULTS: The presented plasma probe provides improved safety with respect to arcing, ozone generation and electric shock, compared with conventional designs. The functionality of previously reported devices is expanded. A defined plasma diameter can be set by choosing the appropriate insert, while the input voltage controls the plasma temperature. The variation of measurement parameters enables the optimized direct detection of target compounds from roasted coffee beans, such as caffeine, guaiacol and vanillin. CONCLUSIONS: The presented low-temperature plasma probe allows the fine-tuning of ionization and desorption parameters, according to the target molecules. Possible applications include: (1) The ambient ionization and desorption of organic compounds with different volatility and (2) The direct analysis of food products such as roasted coffee beans"
Keywords:		"Coffee/chemistry Cold Temperature Mass Spectrometry/*instrumentation/methods Models, Chemical Organic Chemicals/*analysis/*chemistry Plasma Gases/*chemistry Seeds/chemistry;"
Notes:		"MedlineMartinez-Jarquin, Sandra Winkler, Robert eng Research Support, Non-U.S. Gov't England 2013/02/16 Rapid Commun Mass Spectrom. 2013 Mar 15; 27(5):629-34. doi: 10.1002/rcm.6494"