Differential mobility spectrometry

G.A. Eiceman, E.V. Krylov, N.S. Krylova, E.G. Nazarov and R.A. Miller, Separation of ions from explosives in differential mobility spectrometry by vapor-modified drift gas, Analytical Chemistry 76(17) (2004) 4937-4944. 

Explosives Detection Using Differential Mobility Spectrometry... 

Fig. 6. Schematic of a differential mobility spectrometer showing the principles of ion separation in a differential mobility spectrometry (DMS) drift tube. Ion paths are governed by both the asymmetric electric field and field dependence of mobility for an ion. The inset displays the asymmetric waveform of separation electric field used in the DMS drift tube. The waveforms shown are theoretical (top part) and actual or experimental (bottom part) used in these experiments.

Fig. 16. Gas chromatography-differential mobility spectrometry (GC-(DMS) topographic plot [retention time (v-axis), compensation voltage (y-axis), intensity (z-axis)] of a mixture of seven explosives (lOOng in acetonitrile) hexamethylene triperoxide diamine (HMTD), ethylene glycol dinitrate (EGDN), triacetone triperoxide (TATP), 2-mononitrotoluene (2-MNT), 4-MNT, 2,4-dinitrotoluene (2,4-DNT), and 2,4,6-trinitrotoluene (TNT).

Fig. 17. A commercial configuration of high-speed gas chromatography-differential mobility spectrometry (GC-DMS) is the Defender (flow schematic top left, instrument top right), which is a successor of the EGIS and EGIS II explosives analyzers. Calibration curve of trinitrotoluene (TNT) (bottom left) and ethylene glycol dinitrate (EGDN) (bottom right) (signal vs. mass in...

Kolakowski, B.M., Mester, Z. (2007). Review of applications of high-field asymmetric waveform ion mohility spectrometry (FAIMS) and differential mobility spectrometry (DMS). Analyst 132 842-64. 

Eiceman, G.A. Ion Preparation before Differential Mobility Spectrometry including DMS/DMS Analyzers, PittCon 2010, Orlando, FL, February 2010. 

An, X. Stone, J.A. Eiceman, G.A., Gas phase fragmentation of protonated esters in air at ambient pressure through ion heating by electric field in differential mobility spectrometry and by thermal bath in ion mobility spectrometry, Int. J. Mass Spectrom. 2011, 303(2-3), 181-190. 

Microfabricated drift tubes for differential mobility spectrometry microAnalyzer now produced in Draper Laboratory... 

Sometimes, membrane inlets are operated at the same temperature as the IMS ceU, and sometimes they are operated at elevated temperatures. More recently, advantages of controlling the temperature of the membrane separate from that of the cell have been reported. The primary advantage of temperature-controlled membranes for sample introduction to an IMS is the ability to concentrate the sample and then heat the membrane to provide low-resolution separations as the analytes diffuse through the membrane. One application of this active membrane technology is the detection of benzene in water by photoionization differential mobility spectrometry. " Drawbacks of using membranes are rednced sensitivity, increased response times, and longer clearance times (i.e., memory effects). 

The application of GC for the introduction of complex samples into field asymmetric IMS (FAIMS) and differential mobility spectrometry (DMS) instruments is also used extensively. Fast capillary chromatography in which relatively simple mixtures can be separated in less than a second provides a rapid separation-and-introduction method for DMS. One specific advantage of FAIMS (or DMS) as a chromatographic detector is that both positive and negative ions can be monitored simultaneously from the GC effluent. Figure 3.10 provides a schematic of a typical capillary GC/DMS instrument in which SPME is used to inject semivolatile compounds into the capillary column with DMS detection. 

FIGURE 3.10 Experimental setup of GC-DMS system. Chemical analysis is performed using gas chromatography differential mobility spectrometry (GC/DMS). Several user-defined parameters were selected factorial experiments (a) the RF voltage of the DMS sensor, (b) nitrogen carrier gas flow rate through the DMS, (c) solid phase microextraction (SPME) filter type, and (d) GC cooling profile. (From Molina et al.. Anal. Chim. Acta 368(2), 2008.)... 

Cagan, A. Schmidt, H. Rodrignez, J.E. Eiceman, G.A., Fast gas chromatography-differential mobility spectrometry of explosives from TATP to Tetryl without gas atmosphere modifiers, Int. J. Ion Mobil. Spectmm. 2010. 

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