Development of a palm portable mass spectrometer

Abstract

A palm portable mass spectrometer (PPMS) has been developed with a weight of 1.48 kg (3 lb) and a size of 1.54 L (8.2 X 7.7 X 24.5 em") that can be operated with an average battery power of 5 W. A miniaturized ion trap has been used as a mass analyzer that consists of four parallel disks with coaxial holes. A rf voltage of 1500 V p _ p at 3.9 MHz has been used for scanning ion mass of up to m/z300. An ion-getter pump serves for high vacuum of the PPMS. Sample gas was introduced in pulse mode. An embedded microcomputer has been developed for system control. Detection of organic gases diluted in the air has been demonstrated up to 6 ppm for toluene and 22 ppm for dimethyl methylphosphonate (DMMP (CWA) in the field, the monitoring of air pollution and environmental quality, the inspection of explosives and drugs by homeland security, and the analysis of gases during space exploration. Although the mass spectrometer is one of the most powerful tools of chemical analysis, its use in the field as a portable device has been limited mainly because of its size, weight, and power requirements. For this reason, alternative methods have been widely used for chemical agent detection in the field [1-3], e.g., ion mobility spectrometry (IMS), flame photometry, infrared spectroscopy, electrochemistry, color change chemistry, surface acoustic wave, photo-ionization, conductive polymer, flame-ionization, etc. The basic concept of IMS is to characterize chemical substances through gas-phase ion mobility at atmospheric pressure [4]. An advantage of IMS is that it does not need a vacuum pump, and so its weight and size can be reduced. However, a disadvantage is the poor resolution and broadening of the ion flight time distribution caused by ions continually colliding with air molecules. For this reason, the rate of false alarms is high when other chemical substances are present in the background. Another disadvantage is the need for an intense radiation source for ionization at atmospheric pressure, which can give rise to environmental issues. Other devices using surface acoustic waves or conductive polymers are very compact in size, but these do not display spectrum-based information of Address reprint requests to Dr. M. Yang, Analytical Instrumentation Research Institute, Sam Yang Chemical Co., Seoul, Korea. E-mail: dryangmo@yahoo.com unknown gases [5], and can only be used for confirming the presence of a specific group of agents. In the field, the capability for not only detection but also identification is very important because specific identification of a poison gas is needed for immediate detoxification of victims. However, the identification of chemical substances in the field with a personal mobile device has not yet been successfully achieved.A mass spectrometer is uniquely able to differentiate chemical substances based on molecular mass spectra. A number of mass spectrometers have been developed for military use, such as MMI [1] and CBMS [6]. However, these are large and heavy, and are deployed only as vehicle mounted...

Direct and Sensitive Detection of CWA Simulants by Active Capillary Plasma Ionization Coupled to a Handheld Ion Trap Mass Spectrometer

“…Latest trends in instrument development focus on the development of miniaturized and portable MS systems, making them available for possible on-site use [5][6][7]. Although, there have been some reports on portable/handheld MS instruments for CWA detection, [8,9] all these systems suffer from a reduced selectivity and greatly decreased sensitivity compared with laboratory equipment.…”

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“…Another fascinating development that took place in parallel was the development of portable or miniaturized mass spectrometers [9 -14]. An entire issue of this journal [JASMS 2008, 19(10)] has been devoted to this topic under the heading "Harsh Environment Mass Spectrometry" [12,13,[15][16][17][18][19][20][21][22]. Although all of the field-portable mass spectrometers available nowadays are less powerful in terms of sensitivity, mass range, and mass resolving power than their laboratory-based counterparts, the vision is clearly to combine suitable atmospheric pressure sources with portable mass spectrometers to run analyses in subway systems, airports, at sports events, in restaurants, supermarkets, wholesale markets, and perhaps in the future even in the average home.…”

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