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1.
Ion mobility spectrometers are extremely fast and sensitive sensors for trace gases, which identify these according to their motion through a neutral gas under the influence of an electric field. In this work, the basics of ion mobility are summarized, different areas of application for ion mobility spectrometers are explained and three basic types of ion mobility spectrometers are presented. 相似文献
2.
The ion mobilities of halogenated aromatics which are of interest in environmental chemistry and process monitoring were characterized with field-deployable ion mobility spectrometers and differential mobility spectrometers. The dependence of mobility of gas-phase ions formed by atmospheric-pressure photoionization (APPI) on the electric field was determined for a number of structural isomers. The structure of the product ions formed was identified by investigations using the coupling of ion mobility spectrometry with mass spectrometry (APPI-IMS-MS) and APPI-MS. In contrast to conventional time-of-flight ion mobility spectrometry (IMS) with constant linear voltage gradients in drift tubes, differential mobility spectrometry (DMS) employs the field dependence of ion mobility. Depending on the position of substituents, differences in field dependence were established for the isomeric compounds in contrast to conventional IMS in which comparable reduced mobility values were detected for the isomers investigated. These findings permit the differentiation between most of the investigated isomeric aromatics with a different constitution using DMS. 相似文献
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Detection of human metabolites using multi-capillary columns coupled to ion mobility spectrometers 总被引:4,自引:0,他引:4
Ruzsanyi V Baumbach JI Sielemann S Litterst P Westhoff M Freitag L 《Journal of chromatography. A》2005,1084(1-2):145-151
The human breath contains indicators of human health and delivers information about different metabolism processes of the body. The detection and attribution of these markers provide the possibility for new, non-invasive diagnostic methods. In the recent study, ion mobility spectrometers are used to detect different volatile organic metabolites in human breath directly. By coupling multi-capillary columns using ion mobility spectrometers detection limits down to the ng/L and pg/L range are achieved. The sampling procedure of human breath as well as the detection of different volatiles in human breath are described in detail. Reduced mobilities and detection limits for different analytes occurring in human breath are reported. In addition, spectra of exhaled air using ion mobility spectrometers obtained without any pre-concentration are presented and discussed in detail. Finally, the potential use of IMS with respect to lung infection diseases will be considered. 相似文献
5.
Ion mobility-mass spectrometry 总被引:3,自引:0,他引:3
This review article compares and contrasts various types of ion mobility-mass spectrometers available today and describes their advantages for application to a wide range of analytes. Ion mobility spectrometry (IMS), when coupled with mass spectrometry, offers value-added data not possible from mass spectra alone. Separation of isomers, isobars, and conformers; reduction of chemical noise; and measurement of ion size are possible with the addition of ion mobility cells to mass spectrometers. In addition, structurally similar ions and ions of the same charge state can be separated into families of ions which appear along a unique mass-mobility correlation line. This review describes the four methods of ion mobility separation currently used with mass spectrometry. They are (1) drift-time ion mobility spectrometry (DTIMS), (2) aspiration ion mobility spectrometry (AIMS), (3) differential-mobility spectrometry (DMS) which is also called field-asymmetric waveform ion mobility spectrometry (FAIMS) and (4) traveling-wave ion mobility spectrometry (TWIMS). DTIMS provides the highest IMS resolving power and is the only IMS method which can directly measure collision cross-sections. AIMS is a low resolution mobility separation method but can monitor ions in a continuous manner. DMS and FAIMS offer continuous-ion monitoring capability as well as orthogonal ion mobility separation in which high-separation selectivity can be achieved. TWIMS is a novel method of IMS with a low resolving power but has good sensitivity and is well intergrated into a commercial mass spectrometer. One hundred and sixty references on ion mobility-mass spectrometry (IMMS) are provided. 相似文献
6.
A. Bohnhorst A. T. Kirk S. Zimmermann 《International Journal for Ion Mobility Spectrometry》2016,19(2-3):167-174
Miniaturized low-cost drift tubes with high analytical performance are a key component for the design of powerful and mass-deployable hand-held ion mobility spectrometers. Thus, a simple model that estimates the influence of the geometrical dimensions on the analytical performance is highly desirable for an effective design process. In this work, we present a simple procedure to predict peak distortion based on only the electrical field distribution inside the drift tube, which can be rapidly simulated using the finite element method. A simulation of the ion motion is not required. Based on these results, we developed an ion mobility spectrometer manufactured entirely from standard printed circuit boards (PCB). Since no additional components were used apart from electrical and gas connectors, ion source and metal grids, the presented ion mobility spectrometer is very simple and inexpensive. Nevertheless, the design provides a resolving power of 82 at a drift length of 50 mm and a drift voltage of 3 kV using a tritium ion source and a field switching shutter. The limits of detection for one second of averaging are 80 pptv for acetone, 35 pptv for dimethyl methylphosphonate and 180 pptv for methyl salicylate. 相似文献
7.
Bertram Bödeker Wolfgang Vautz Jörg Ingo Baumbach 《International Journal for Ion Mobility Spectrometry》2008,11(1-4):77-81
Ion mobility spectrometers (IMS) are used widely to detect explosives, illegal drugs and chemical warfare agents. More than 70.000 units are under operation world-wide. One of the insufficiencies for broad use of different types of ion mobility spectrometers for civilian applications in the scientific or commercial world is the self- or company-made data format, thus complicating any further step towards a consistent evaluation. The problem starts with rather simple visualisation software for rather complex data structures. We describe a Java based software platform with respect to visualisation of IMS data, especially data of IMS coupled to Multi-capillary columns (MCC). 相似文献
8.
Larry A. Viehland Tamar Skaist Chetana Adhikari William F. Siems 《International Journal for Ion Mobility Spectrometry》2017,20(1-2):1-9
The zero-field mobilities of many atomic ions in rare gases are calculated from highly accurate, ab initio potential energy curves. They are expected to be accurate to at least 0.05%, thus allowing them to be used to calibrate mobility measurements in different drift-tube and ion mobility mass spectrometers. 相似文献
9.
Bert Ungethüm Andreas Walte Wolf Münchmeyer Gerhard Matz 《International Journal for Ion Mobility Spectrometry》2009,12(4):131-137
Small concentrations of toxic compounds in atmospheric air have often to be measured selectively by portable equipment. Ion
mobility spectrometers are instruments used to monitor explosives, drugs and chemical warfare agents. First responders also
need to detect hazardous gases released in accidents while transporting them or in their production in chemical plants. Not
all toxic gases can be measured with the time of flight ion mobility spectrometer at concentrations required by safety standards
applied in workplace areas. The time of flight ion mobility spectrometer is based on an inlet membrane, an ionization region,
a shutter grid and the drift region with a detector in the drift tube. The separation of ions is due to the different mobility
of the ions when they are exposed to a weak electric field (E = 200…300 V/cm). High field asymmetric waveform spectrometry
or differential mobility spectrometry is a relative new ion mobility spectrometer technology. The separation is due to the
different mobilities of the ions in the high (E = 15000...30000 V/cm) and the weak electric fields. About 30 different toxic
industrial chemical compounds were analyzed with both systems under comparable conditions. For selected examples the detection
limits, the selectivity and the identification capabilities of the two systems for some of the main compounds will be discussed. 相似文献
10.
Clinton A. Krueger Christopher K. Hilton Mark Osgood Jianglin Wu Ching Wu 《International Journal for Ion Mobility Spectrometry》2009,12(1):33-37
Current commercially available ion mobility spectrometers are intended for the analysis of chemicals in the gas phase. Sample
introduction methods, such as direct air sampling, a GC injector or a thermal desorber, are commonly an integral part of these
instruments. This paper describes an electrospray ionization ion mobility spectrometer system that allows direct introduction
samples in solution phase. This allows direct analysis of non-volatile organic and biological samples, and avoids decomposition
of thermally liable samples, providing reliable chemical identification. In addition, the new ion mobility spectrometer allows
mobility analysis with high resolving power. Commonly used commercial IMS systems provide resolving powers between 10 and
30; this new ion mobility spectrometer has resolving power greater than 60 for routine analysis. A high resolution instrument
is necessary for many applications where a complex mixture needs to be separated and quantified. This paper demonstrates the
advantages of using a high resolution ion mobility spectrometer and an electrospray ionization source for the analysis of
non-volatile pharmaceuticals as well as dissolved explosive in solution phase. 相似文献
11.
Richard A. Hancock Raymond Walder Helmut Weigel 《Journal of mass spectrometry : JMS》1979,14(9):507-511
Consequential upon determinations of kinetic rate constants of ion/molecule reactions in methane and isobutane, simple equations are presented from which the pressures of methane and isobutane in the ion source of chemical ionization mass spectrometers can be calculated. Account is taken of the design of the ion source and it is only necessary to determine two ion currents for each gas. 相似文献
12.
Mark E. Ridgeway Jeremy J. Wolff Joshua A. Silveira Cheng Lin Catherine E. Costello Melvin A. Park 《International Journal for Ion Mobility Spectrometry》2016,19(2-3):77-85
Analysis of molecules by ion mobility spectrometry coupled with mass spectrometry (IMS-MS) provides chemical information on the three dimensional structure and mass of the molecules. The coupling of ion mobility to trapping mass spectrometers has historically been challenging due to the large differences in analysis time between the two devices. In this paper we present a modification of the trapped ion mobility (TIMS) analysis scheme termed “Gated TIMS” that allows efficient coupling to a Fourier Transform Ion Cyclotron Resonance (FT-ICR) analyzer. Analyses of standard compounds and the influence of source conditions on the TIMS distributions produced by ion mobility spectra of labile ubiquitin protein ions are presented. Ion mobility resolving powers up to 100 are observed. Measured collisional cross sections of ubiquitin ions are in excellent qualitative and quantitative agreement to previous measurements. Gated TIMS FT-ICR produces results comparable to those acquired using TIMS/time-of-flight MS instrument platforms as well as numerous drift tube IMS-MS studies published in the literature. 相似文献
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The distribution of charge z and radii R in clusters electrosprayed from formamide solutions of tetraheptylammonium bromide was investigated by selecting those within a narrow range of electrical mobilities Z(1) in a first differential mobility analyzer (DMA), reducing their charge to unity by passage through a neutralizing chamber containing a radioactive (alpha) source, and measuring the mobilities Z(z) of the resulting discrete set of singly charged clusters in a second DMA. After correcting for the polarization contribution to cluster drag, the tandem DMA data yield the range of radii present at detectable levels for each charge state up to z = 9. Because small ion evaporation from electrospray drops leads to charge loss when a drop reaches a certain critical radius R(crit)(z), the measured maximum and minimum cluster radii associated with a given z can be used to infer the activation energy Delta for ion evaporation as a function of drop charge and curvature. These results confirm the Iribarne-Thomson ion-evaporation mechanism, and support earlier theoretical expressions for the functional form of Delta(z,R). The different phenomenon of ion evaporation from metastable multiply charged dry clusters is also observed at characteristic times of 1 s. Its activation energy is estimated as approximately 0.3 eV larger than for ion evaporation from the drops. This new process complicates the interpretation of the present measurements in terms of ion evaporation from liquid surfaces, but introduces no radical change in the picture. It helps understand why salt clusters with more than two or three charges are harder to see in mass spectrometers than in mobility studies under ambient conditions. Copyright 2000 John Wiley & Sons, Ltd. 相似文献
16.
Wolfgang Vautz Bertram Bödeker Jörg Ingo Baumbach Sabine Bader Michael Westhoff Thorsten Perl 《International Journal for Ion Mobility Spectrometry》2009,12(2):47-57
Ion mobility spectrometry is increasingly in demand for medical applications and its potential for implementation in food
quality and safety or process control suggest rising use of instruments in this field as well. All those samples are commonly
extremely complex and mostly humid mixtures. Therefore, pre-separation techniques have to be applied. As ion mobility spectrometers
with gas-chromatographic pre-separation acquire a huge amount of data, effective data processing and automated evaluation
by comparison of detected peak pattern with data bases have to be utilised. This requires accurate on-line calibration of
the instruments to guarantee reproducible results, in particular with respect to identification of an analyte by determination
of its ion mobility and retention time. To reduce environmental and instrumental influence, the reduced ion mobility is used.
It is derived from the drift time normalised to electric field, length of the drift region and to temperature and pressure
of the drift gas (traditional method). All data required for this normalisation are afflicted with a particular error and
thus leading to a deviation of the calculated ion mobility value. Furthermore, this traditional method enables a calculation
of the reduced ion mobility only after the measurement. To avoid those errors and to enable on-line calibration of ion mobility,
an instrument specific factor is implemented generally representing all relevant variables. This factor can be determined
from an initial measurement of few spectra and can thereafter be applied on the following measurement. The application of
this approach obtained reproducible reduced ion mobility values for positive and negative ions over a broad drift time range
and for common variation of ambient conditions as well for varying instrument conditions such as electric fields respectively
drift times and in different drift gases. Moreover, the reduced ion mobility is available already during the measurements
with a significantly higher reliability and accuracy which was increased to a factor of 5 compared to the traditional ion
mobility determination and enables an on-line identification of analytes for the first time. 相似文献
17.
A. Cagan H. Schmidt J. E. Rodriguez G. A. Eiceman 《International Journal for Ion Mobility Spectrometry》2010,13(3-4):157-165
Explosives in solution were determined as mixtures containing highly volatile improvised explosives such as peroxides and conventional military grade explosives such as PETN, RDX, and Tetryl using a high speed gas chromatograph with differential mobility detector in a single measurement. Instrument parameters were evaluated and adjusted to permit detection of nanogram amounts of explosives with this broad range of vapor pressures in times under 3 min for HMTD to TNT or under 16 min for HMTD to Tetryl. As in prior studies of response to explosives with mobility spectrometers, pre-separation of sample by gas chromatography improved response in the differential mobility detector; however, unlike prior configurations, the supporting gas atmosphere did not contain modifiers to adjust selectivity in mobility and selectivity was provided only by characteristic stability of product ions in negative and positive polarities. Field dependence of product ions in purified air was determined for each explosive and patterns were sufficiently distinct to suggest the addition of selectivity through the use of several differential mobility detectors operated in parallel or series with characteristic separation voltages. 相似文献
18.
Ansgar T. Kirk Kai Bakes Stefan Zimmermann 《International Journal for Ion Mobility Spectrometry》2017,20(3-4):105-109
The drift voltage is one of the key experimental parameters of any drift tube ion mobility spectrometer. In this work, we show that a universal relationship between optimum drift voltage and the resolving power reached at this point exists, governed only by temperature and ion charge state. With these two quantities known, the measured optimum drift voltage and resolving power combination can be used to estimate the ideality of the drift conditions inside a drift tube, since any deviation from the theoretical values must be caused by non-idealities in the ions’ drift. Analyzing drift voltage sweeps from nine different ion mobility spectrometers, a continuous increase in drift tube ideality over the past is observed, reaching from less than 50% thirty years ago to 99% for a current design based on printed circuit boards. Furthermore, possible causes for the observed non-idealities are discussed. 相似文献
19.
Andre Heptner Nico Angerstein Tobias Reinecke Erik Bunert Ansgar T. Kirk Igor Niedzwiecki Stefan Zimmermann 《International Journal for Ion Mobility Spectrometry》2016,19(4):175-182
For the ionization of gas mixtures, several ionization sources can be coupled to an ion mobility spectrometer. Radioactive sources, e.g. beta radiators like 63Ni and 3H, are the most commonly used ionization sources. However, due to legal restrictions radioactive ionization sources are not applicable in certain applications. Non-radioactive alternatives are corona discharge ionization sources or photoionization sources. However, using an electron gun allows regulation of ion production rate, ionization time and recombination time by simply changing the operating parameters, which can be utilized to enhance the analytical performance of ion mobility spectrometers. In this work, the impact of an ionization source parameter variation on the ion mobility spectrum is demonstrated. Increasing the ion production rate, the amount of the generated ions increases leading to higher signal intensity while the noise remains constant. Thus, the signal to noise ratio can be increased, leading to better limits of detection. In a next step, the ion production rate is kept constant while the influence of ionization time on the ion mobility spectrum is investigated. It is shown, that varying the ionization time allows the determination of the reaction rate constants as additional information to the ion mobility. Furthermore, we show the prevention of discrimination processes by using short ionization times combined with an increased ion production rate. Thus, the limit of detection for benzene in presence of toluene is improved. Additionally, it is shown that using ion-ion recombination leads to the detection of the ion species with the highest proton affinity at higher recombination times while the low proton affine ions already recombined. Thus, the measurement of the ion mobility spectra at a defined recombination time allows a suppression of disturbing low proton affine substances. 相似文献
20.
Glenn E. Spangler 《International Journal for Ion Mobility Spectrometry》2012,15(3):109-121
Using the Langevin equation for ion motion in the presence of a variable electric field, and expressing the collision frequency in a manner that conforms to scattering a polyatomic ion with an equivalent hard-sphere core, a relationship is derived for the compensation and dispersion fields in a differential ion mobility spectrometer (DIMS). For a conservative collision (no clustering or ion-neutral dissociation or rearrangement interactions), the compensation field depends on both even and odd powers of the dispersion field, and the relationship between both fields is independent of pressure when the fields are divided by the drift gas density. Because the first and most important approximation for the compensation field is proportional to the square of ion mobility under zero field conditions, the compensation field increases with the temperature of the drift gas, but the functional form for the temperature dependence involves higher order terms and requires additional knowledge of the temperature dependence for the collision cross section. Duty cycle curves for long-chain secondary ketones compare favorably to experiments using an asymmetric rectangular waveform for excitation. 相似文献