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Tadjimukhamedov F.K.,Purdue University | Jackson A.U.,Purdue University | Nazarov E.G.,Sionex Corporation | Ouyang Z.,Purdue University | Cooks R.G.,Purdue University
Journal of the American Society for Mass Spectrometry | Year: 2010

A planar differential mobility spectrometer (DMS) was coupled to a Mini 10 handheld rectilinear ion trap (RIT) mass spectrometer (MS) (total weight 10 kg), and the performance of the instrument was evaluated using illicit drug analysis. Coupling of DMS (which requires a continuous flow of drift gas) with a miniature MS (which operates best using sample introduction via a discontinuous atmospheric pressure interface, DAPI), was achieved with auxiliary pumping using a 5 L/min miniature diaphragm sample pump placed between the two devices. On-line ion mobility filtering showed to be advantageous in reducing the background chemical noise in the analysis of the psychotropic drug diazepam in urine using nanoelectrospray ionization. The combination of a miniature mass spectrometer with simple and rapid gas-phase ion separation by DMS allowed the characteristic fragmentation pattern of diazepam to be distinguished in a simple urine extract at lower limits of detection (50 ng/mL) than that achieved without DMS (200 ng/mL). The additional separation power of DMS facilitated the identification of two drugs of similar molecular weight, morphine (average MW = 285.34) and diazepam (average MW = 284.70), using a miniature mass spectrometer capable of unit resolution. The similarity in the proton affinities of these two compounds resulted in some cross-interference in the MS data due to facile ionization of the neutral form of the compound even when the ionic form had been separated by DMS. © 2010.

Krylov E.,Sionex Corporation
International Journal for Ion Mobility Spectrometry | Year: 2012

Differential mobility spectrometer is a powerful tool used for detection, filtration and characterization of ions in gas-phase. DMS instrumentation analytical performance is a matter of importance for practical application. This paper is devoted to the improving of the planar DMS analytical characteristics. The goal is to optimize ion transmission and separation efficiency for the best possible DMS performance, balanced between sensitivity and selectivity. Analytical characteristics of the DMS instrument depend on a number of interrelated parameters. Present paper focuses on the sensor geometry and transport gas flow rate and its influence on the DMS performance. To find optimal sensor design parameters a systematic approach to the DMS performance is provided and evaluated both theoretically and experimentally. To facilitate DMS optimization special criterion quantitatively describing DMS analytical quality is proposed. DMS instrumental parameters maximizing analytical quality are determined. Theoretical analysis is validated by comparison with experimental data. Practical recommendations following from these finding are presented. © 2012 Springer-Verlag.

Sionex Corporation | Date: 2009-01-13

Sensors, detectors, monitors, spectrometers, ion filters and ion separators, all for the detection, analysis, separation and use of chemicals, including biochemicals.

Roetering S.,University of Applied Sciences of Leipzig | Nazarov E.G.,Sionex Corporation | Borsdorf H.,Helmholtz Center for Environmental Research | Weickhardt C.,University of Applied Sciences of Leipzig
International Journal for Ion Mobility Spectrometry | Year: 2010

The chances to improve the detection of pesticides using differential mobility spectrometry (DMS) with an atmospheric pressure photoionization (APPI) ion source by means of dopants was investigated. The effect of employing benzene, anisole and chlorobenzene as dopants is described regarding sensitivity, limits of detection and peak displacements in the spectra. For typical pesticides an improvement of detection limits up to two orders of magnitude could be determined, while for the peak shift of individual substances no uniform behaviour was observed. Possible mechanisms of action in respect to atmospheric pressure photoionization (APPI) processes are discussed. © 2010 Springer-Verlag.

Coy S.L.,Sionex Corporation | Krylov E.V.,Sionex Corporation | Schneider B.B.,AB SCIEX | Covey T.R.,AB SCIEX | And 6 more authors.
International Journal of Mass Spectrometry | Year: 2010

Technology to enable rapid screening for radiation exposure has been identified as an important need, and, as a part of a NIH/NIAD effort in this direction, metabolomic biomarkers for radiation exposure have been identified in a recent series of papers. To reduce the time necessary to detect and measure these biomarkers, differential mobility spectrometry-mass spectrometry (DMS-MS) systems have been developed and tested. Differential mobility ion filters preselect specific ions and also suppress chemical noise created in typical atmospheric-pressure ionization sources (ESI, MALDI, and others). Differential-mobility-based ion selection is based on the field dependence of ion mobility, which, in turn, depends on ion characteristics that include conformation, charge distribution, molecular polarizability, and other properties, and on the transport gas composition which can be modified to enhance resolution. DMS-MS is able to resolve small-molecule biomarkers from isobaric interferences, and suppresses chemical noise generated in the ion source and in the mass spectrometer, improving selectivity and quantitative accuracy. Our planar DMS design is rapid, operating in a few milliseconds, and analyzes ions before fragmentation. Depending on MS inlet conditions, DMS-selected ions can be dissociated in the MS inlet expansion, before mass analysis, providing a capability similar to MS/MS with simpler instrumentation. This report presents selected DMS-MS experimental results, including resolution of complex test mixtures of isobaric compounds, separation of charge states, separation of isobaric biomarkers (citrate and isocitrate), and separation of nearly isobaric biomarker anions in direct analysis of a bio-fluid sample from the radiation-treated group of a mouse-model study. These uses of DMS combined with moderate resolution MS instrumentation indicate the feasibility of field-deployable instrumentation for biomarker evaluation. © 2010 Elsevier B.V. All rights reserved.

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