Spectrometer, portable mass

Mass spectrometers have been used at some level in all of these types of investigations because of their unsurpassed sensitivity and specificity, their multicomponent analytical capability and, in some cases, their ability to provide precise and accurate isotope ratios. Traditional methods of analysis typically involve the collection of water and sediment samples, or biological specimens, during field expeditions and cmises on research vessels (R/Vs), and subsequent delivery of samples to a shore-based laboratory for mass spectrometric analyses. The recent development of field-portable mass spectrometers, however, has greatly facilitated prompt shipboard analyses. Further adaptation of portable mass spectrometer technology has also led to construction of submersible instruments that can be deployed at depth for in situ measurements. 

Short RT, Toler SK, Kibelka GPG, Roa DTR, Bell RJ, Byrne RH (2006) Detection and quantification of chemical plumes using a portable underwater membrane introduction mass spectrometer. Trends Anal Chem 25 637-646... 

For more volatile compounds, the simplest procedure is to build a small vacuum line to handle sensitive materials. Depending on the mass spectrometer this may either be permanently attached or portable. 

Mass spectrometry (MS) is highly selective. The ability to further perform tandem mass spectrometry (MS/MS) analysis when a compound is detected to confirm the detection virtually eliminates false positive and negative alarms. But MS/MS analysis must be completely automated for the average GI to be able to perform it. A clever hand-held chemical and biological mass spectrometer has been developed that weighs only 4.3 pounds. The problem with the unit is production of the necessary vacuum, which requires 35 amps at 24 volts. Thus, battery-operated portable mass spectrometry is not yet available. 

Biological and chemical welfare constitutes a hidden menace since the first world war. Monitoring of these agents is now made possible by sensitive, soft-ionization portable mass spectrometers. 

Design and Operation of a Portable Quadrupole Mass Spectrometer for the Undergraduate Curriculum 79... 

More than 104 ion mobility spectrometers are deployed at airport security checkpoints to detect explosives, and perhaps 105 hand-portable devices are used by military and civil defense personnel. Although functionally similar to mass spectrometers, mobility spectrometers are operated in air at ambient pressure and ion mobility spectrometry is not a form of mass spectrometry. Ion mobility spectrometry does not measure molecular mass and provides no structural information. However, it is so widely used that we introduce it here. 

P. E. Miller and M. B. Denton, The Quadrupole Mass Filter Basic Operating Concepts, J. Chem. Ed. 1986, 63, 617 M. Henchman and C. Steel, Design and Operation of a Portable Quadrupole Mass Spectrometer for the Undergraduate Curriculum, J. Chem. Ed. 1998, 75, 1042 C. Steel and... 

The planar integrated micro mass spectrometer—one of the new mass spectrometers under development—is also introduced here. Such a portable handheld micro mass spectrometer would be very useful for bedside therapeutic drug monitoring. 

A 30-lb field-portable quadrupole ion trap TOF (QitTof) mass spectrometer with an atmospheric photoionization source was constructed [17]. The photoionization source has the ability to choose a narrow-band ionization energy that is sufficiently high to ionize and detect most compounds of interest but low enough to avoid ionization of most common air constituents, such as N2, 02, H20, C02, CO, Ar, etc. Fragmentation is minimal because ionization occurs just above the ionization thresholds, with very little excess energy. The ion trap stores ions from a continuous ionization source followed by pulsed extraction into the TOF mass analyzer. 

Desorption electrospray ionization was implemented on this portable mass spectrometer [23], DESI experiments were carried out at ambient capillary temperature, at a spray voltage of 3kV and a nebulizing N2 gas flow of 80-120 psi. Detection of RDX from three different surfaces (paper, plastic, and metal) was demonstrated with this portable instrument in the positive-ion mode, with an analysis time of 5-10 s. The result obtained for 10 ng of RDX deposited on 1-cm2 paper is shown in Fig 11(a). Figure 11(b) shows... 

Issues of size, portability, and power requirements have been addressed during the last years, and miniature and mobile mass spectrometers have been developed, based on a variety of mass analyzers. Also, different ionization techniques, such as ESI and DESI, have been applied for the detection of explosives. 

The technology of GC-MS can be downsized for field usage and is now commercially available. Inficon (USA) manufactures a field-portable GC-MS, Hapsite. Vapor is withdrawn for 30 s into the Tenax preconcentration system, thermally desorbed into the apolar capillary colmnn with elevated temperature control, and the separated components are finally analyzed by the electron ionization quadrupole mass spectrometer. GB, GD, GA, and HD are detected and identified within 12 min with postulated LOD values of 0.2, 0.5, 8, and 0.3 pg/m (Sekiguchi et al, 2006). Gaseous and weakly volatile (boiling temperature >250°C) CWAs cannot be detected. 

Sekiguchi, H., Matsushita, K., Yamashiro, S., Sano, Y., Seto, Y., Okuda, T., Sato, A. (2006). On-site determination of nerve gases and mustard gas using a field-portable gas chromatography-mass spectrometer. Forensic Toxicol. 24 17-22. 

Isotopic analysis separates isotopes on the basis of smaU but significant differences in mass (see Chapter 31 by Lipschultz, this volume). This can be done using an emission spectrometer or a mass spectrometer. With both types of instruments, the sample must be converted to a gas prior to analysis. Emission spectrometers operate based on the principle that a N2 gas molecule comprised of a and wiU fluoresce at a different frequency then a molecular comprised of two Ns or two Ns (reviewed in Preston, 1993). Isotope ratio mass spectrometers separate and quantify the different N2 gas molecules based on their behavior when they are accelerated through a magnetic field (reviewed in Mulvaney, 1993). Emission spectrometers seem to have faUen out of favor in the quest for bigger and better instruments. They do have advantages, however. Emission spectrometers are much cheaper to purchase and maintain, they are portable, they require smaUer masses of N for analysis than many mass spectrometers, and there is no possibility for carry over from sample to sample because each sample is sealed in an ampoule prior to analysis. 

One of the instruments obtained by ERDA will be evaluated at ORNL to assess its potential as a monitor for hazardous by-products from alternative energy sources. Investigations to determine the desirability of a membrane inlet system for concentrating organic vapors are planned. The feasibility of using a portable gas chromatograph with the portable mass spectrometer, when a complex mixture analysis is required, is also being studied. 

CEB will be used for coal and waste combustion, and not primarily for heavy fuel oil. However, the projected large-scale test 7 MW, facility can only use heavy fuel oil. Therefore, this oil was used to test it on a small scale. A small flame tunnel with separate air and liquid fuel injectors was constructed to demonstrate the potential of CEB to recover SO2. Figure 10 shows a photograph of the set-up, with the control panel at the right hand, and the flame tunnel in the middle. The three injection ports for CEB material are visible at the front side. Through the opening in the middle (the nozzle has been removed), the flame from diesel combustion is clearly visible. In all experiments, CEB is sprayed perpendicular to the fuel stream. A portable Mass Spectrometer has been purchased to analyse the exit gases from the flame tunnel experiments on SO2. 

Other collection and analytical methods for soil-gas measurement involve the use of a portable mass spectrometer and the use of trained dogs (Kahma et al., 1975). Analytical methods for sulphur gases are summarised in Table 8-111. 

Portable mass spectrometer Several volatile constituents can be determined Expensive, experimental... 

Syage JA, Hanning-Lee MA, Hanold KA. A man-portable, photoionization time-of-flight mass spectrometer. Field Anal Chem Toxicol 2000 4 204-15. 

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