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WO2009144443A1 - Procédés améliorés pour spectrométrie à forme d’onde asymétrique en champ intense (hifaws) - Google Patents

Procédés améliorés pour spectrométrie à forme d’onde asymétrique en champ intense (hifaws) Download PDF

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Publication number
WO2009144443A1
WO2009144443A1 PCT/GB2009/001258 GB2009001258W WO2009144443A1 WO 2009144443 A1 WO2009144443 A1 WO 2009144443A1 GB 2009001258 W GB2009001258 W GB 2009001258W WO 2009144443 A1 WO2009144443 A1 WO 2009144443A1
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WO
WIPO (PCT)
Prior art keywords
water
ppm
molecular weight
hifaws
low molecular
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/GB2009/001258
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English (en)
Inventor
Stuart Keith Ross
Sarah Marchant
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
UK Secretary of State for Defence
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UK Secretary of State for Defence
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from GB0809867A external-priority patent/GB0809867D0/en
Priority claimed from GB0816411A external-priority patent/GB0816411D0/en
Application filed by UK Secretary of State for Defence filed Critical UK Secretary of State for Defence
Publication of WO2009144443A1 publication Critical patent/WO2009144443A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/62—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode
    • G01N27/622—Ion mobility spectrometry
    • G01N27/624—Differential mobility spectrometry [DMS]; Field asymmetric-waveform ion mobility spectrometry [FAIMS]
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/62—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J49/00—Particle spectrometers or separator tubes
    • H01J49/26—Mass spectrometers or separator tubes
    • H01J49/34—Dynamic spectrometers

Definitions

  • the present invention is concerned with methods for performing HIFAWS, and in particular methods in which the electric field dependency of ions is rendered substantially independent of water concentration.
  • HiFAWS High Field Asymmetric Waveform Spectrometry
  • FIMS Field Asymmetric Ion Mobility Spectrometry
  • rf-IMS Radio Frequency Ion Mobility Spectrometry
  • DMS Differential Mobility Spectrometry
  • FIS Field Ion Spectrometry
  • IMS Ion mobility spectrometry
  • HiFAWS is a technique capable of separating a wide variety of ions in the gas phase, from chemical warfare (CW) agents through to protein conformers.
  • Ion identification in HiFAWS is related to changes in effective cross section of the ion and can be based on the propensity of ions to cluster/decluster, often with neutral molecules such as water. Separation of ions via this clustering/declustering mechanism relies on the ability of ions to form clusters with neutral molecules in the presence of low electric fields, resulting in an increased cross-sectional area of ion, and to decluster in the presence of high electric fields, resulting in a decreased cross-sectional area of ion.
  • HiFAWS ions are transported by a carrier gas between two electrodes, whereby an asymmetric waveform is applied to one of the electrodes. Ions are thereby displaced towards one and then the other electrode by the application of the waveform containing a short duration high field component and a slightly longer duration low field component of opposite polarity.
  • the waveform is configured such that if the ion mobility is the same at high and low electric fields, the ion will experience zero net displacement towards an electrode and will be transmitted through the apparatus to the detector. However, at high electric field strengths the mobility of many ions change compared to their low field mobility resulting in a net displacement of the ions towards one or other of the electrodes.
  • CV compensation voltage
  • HiFAWS has found particular utility in the detection of CW agents, such as sarin.
  • CW agents such as sarin.
  • IMS ion mobility spectrometry
  • discrimination of CW agents arises due to field dependence differences associated with the CW agent monomer ions.
  • the dimer ions if present, are not readily resolvable.
  • the field dependency of the monomer ion can be greatly affected by the presence of water vapour, as shown by N Krylova et al, J. Phys. Chem., 2003, 107, 3648 - 3654.
  • water vapour affects the field dependency by clustering around the monomer ion at low field strengths then declustering from the monomer ion at high field strengths where the number of molecules of water clustering around the monomer ion at low field strengths is dependent on the water concentration.
  • water clustering/declustering can be regarded as beneficial in modifying the field dependency of monomer ions, it is also a problem in a detection system as variations in environmental moisture levels may lead to variations of water vapour concentration internally within the cell leading to unpredictable monomer ion field dependence.
  • Water concentration is thus a critical parameter in HiFAWS based detection.
  • Water clustering occurs on application of a low electric field, and water declustering on application of a high electric field following the process A-H + -(H 2 O) n (water clustering) ⁇ A-H + + (H 2 O) n (water declustering) as the applied electric field fluctuates between high field and low field.
  • A-H + -(H 2 O) n water clustering
  • A-H + -(H 2 O) ni + (H 2 O) n-01 water declustering
  • This mechanism is the dominant process that influences the field dependency of CW agent monomer ions.
  • Field dependence is primarily associated with differences in the cross sectional area of the monomer ion.
  • the monomer ion becomes more field dependent as the water concentration increases, i.e. as the number of molecules clustering around the ion increases which thereby increases the cross sectional area of the ion.
  • Low molecular weight solvents such as methanol, 2-propanol, and 2-butanol, have been shown to improve analyte ion separation in HiFAWS analyses by DS Levin et al, Anal. Chem., 2006, 78, 96-106, and in particular in the analysis of peptides, whereby the low molecular weight solvent enables a reduction in the formation of multiply charged non-covalently bound peptide aggregate ions, as further reported by DS Levin et al, Anal. Chem. 2006, 78, 5443-5452.
  • the present application generally aims to provide HiFAWS based methods which alleviate or eradicate the effect of water on the field dependency of ions in HiFAWS.
  • the present invention provides for use of a carrier gas comprising a low molecular weight solvent in HiFAWS detection of a target molecule in a sample, wherein the low molecular weight solvent has a proton affinity higher than that for water, to provide an electric field dependency of target molecule ions substantially independent of any water vapour present in the carrier gas and/or the sample.
  • a low molecular weight solvent is a solvent which is capable of vaporisation at atmospheric pressure, and thus capable of being incorporated into, or modifying, a carrier gas for use in HiFAWS, and has a molecular weight of less than 200.
  • the Applicant has found that the presence of a low molecular weight solvent with a proton affinity higher than that for water in the carrier gas used to flow a target molecule between two electrodes in HiFAWS is capable of alleviating or even eradicating the effect of water on the field dependency of a target molecule ion, and in particular on the field dependency of a monomer ion of the target molecule.
  • the effect of internal moisture in HiFAWS analysis originating from the target sample and/or the carrier gas can therefore be significantly reduced.
  • a low molecular weight solvent of proton affinity higher than that of water also has the effect of reducing the level of ionisation of chemicals in a sample, leading to a more simplified background response during analysis.
  • the concentration of low molecular weight solvent in the carrier gas required to eradicate the effect of any water vapour on the field dependency is dependent on the concentration of water vapour in the sample and/or carrier gas. For example, a concentration of 200 ppm ammonia in the carrier gas is sufficient to eradicate the effect of concentrations of water of at least up to 1000 ppm.
  • concentration of a low molecular weight solvent required to eradicate the effect of a particular water concentration may be determined using routine methods.
  • the concentration of the low molecular weight solvent in the carrier gas will usually be at least 10 ppm, and preferably at least 200 ppm.
  • the low molecular weight solvent is believed to bind/cluster to the target molecule ions in preference to water as a consequence of its higher proton affinity.
  • Ammonia with a proton affinity of 204 kcal/mol binds to the target molecule ion in preference to that of water with a proton affinity of only 165 kcal/mol.
  • the concentration of low molecular weight solvent in the carrier gas can also dramatically affect the field dependence of the target molecule ion with changes in ion cross-sectional area now primarily being due to clustering/declustering of the solvent rather than water.
  • This clustering/declustering can significantly change the effective ion cross sectional area of the target molecule ion resulting in larger high and low field mobility differences than that observed for water clustering/declustering.
  • Preferred low molecular weight solvents are ammonia and ethanol.
  • the present invention also provides for a method for detecting a target molecule in a sample using HiFAWS comprising i. arranging for a HiFAWS apparatus having a region wherein to provide an electric field, and having reactant ions therein,
  • the low molecular weight solvent has a proton affinity higher than that for water, providing for an electric field dependency of target molecule ion substantially independent of any water vapour present in the carrier gas and/or the sample.
  • the method is in particular directed to detecting and identifying chemical warfare agents such as GA, GB and sarin, and chemical warfare simulant molecules such as dimethyl methyl phosphonate (DMMP), a simulant for sarin.
  • chemical warfare agents such as GA, GB and sarin
  • chemical warfare simulant molecules such as dimethyl methyl phosphonate (DMMP), a simulant for sarin.
  • DMMP dimethyl methyl phosphonate
  • the method may also be used for detecting explosives.
  • the HIFAWS apparatus may be replaced with a combined HIFAWS-IMS apparatus. Such a combination may provide for further improved detection of a target molecule.
  • Figures 1 a) to c) are graphical representations of HiFAWS results displaying compensation voltage against RF amplitude of the asymmetric waveform carried out with target molecule DMMP with a water concentration of 200 ppm and a) no low molecular weight solvent, b) 0.1 ppm ammonia, and c) 0.1 ppm acetone;
  • Figures 2 a) to c) are graphical representations of HiFAWS results displaying compensation voltage against RF amplitude of the asymmetric waveform carried out with target molecule DMMP with an ammonia concentration of 1 ppm and a water concentration of a) 10 ppm, b) 200 ppm and c) 1000 ppm;
  • Figures 3 a) to c) are graphical representations of HiFAWS results displaying compensation voltage against RF amplitude of the asymmetric waveform carried out with target molecule DMMP with an ammonia concentration of 200 ppm and a water concentration of a) 10 ppm, b) 200 ppm and c) 1000 ppm;
  • Figures 4 a) to c) are graphical representations of HiFAWS results displaying compensation voltage against RF amplitude of the asymmetric waveform carried out with target molecule DMMP with a methanol concentration of 200 ppm and a water concentration of a) 10 ppm, b) 200 ppm and c) 1000 ppm;
  • Figures 5 a) to c) are graphical representations of HiFAWS results displaying compensation voltage against RF amplitude of the asymmetric waveform earned out with target molecule DMMP with an ethanol concentration of 200 ppm and a water concentration of a) 10 ppm, b) 200 ppm and c) 1000 ppm;
  • Figures 6 a) to c) are graphical representations of HiFAWS results displaying compensation voltage against RF amplitude of the asymmetric waveform carried out with target molecule DMMP with a propan-1-ol concentration of 200 ppm and a water concentration of a) 10 ppm, b) 200 ppm and c) 1000 ppm;
  • Figure 7 a) to c) are graphical representations of the compensation voltage for the DMMP monomer ion in the presence of a water concentration of 25 ppm (2), 200 ppm (3), and 1600 ppm (4).
  • Figure 7a is in absence of ammonia
  • Figure 7b is in the , presence of 0.1 ppm ammonia
  • Figure 7c is in the presence of 200 ppm ammonia;
  • Figure 8 is a schematic for the gas handling system delivering air, water vapour and modifier vapour to the HiFAWS apparatus.
  • HiFAWS apparatus Sionex Value Added Component; SVAC was supplied by Sionex Corporation, Bedford, USA. Topographic dispersion plots were obtained using software developed at Sionex Corporation.
  • the HiFAWS apparatus was modified to interface, via 50 ⁇ m orifice plates, with two separate quadrupole mass spectrometers, one tuned for external positive ions (SXP 600, VG Quadmpoles, UK) and one tuned for negative ions (SXP Elite, VG Quadrupoles, UK).
  • the HiFAWS apparatus was interfaced with mass spectrometry to allow confirmatory identification of ions detected. All trends observed on the Sionex SVAC could be reproduced on the modified apparatus.
  • the modified apparatus excludes detection electrodes so that on application of the appropriate compensation voltage the ions pass directly through the apparatus and into the mass spectrometer, via the pinhole orifice.
  • Driving electronics for the modified apparatus were supplied by Sionex Corporation.
  • All mass flow controllers are manufactured by MKS Instruments and are connected to a MKS four channel readout.
  • the water concentration in the bulk air stream is measured using a MCM Dewmatic (Moisture Control and Measurement, UK) and can be controlled and maintained at any water concentration between 2ppm and lOOOppm.
  • the CW vapour generator is a GIlO vapour generator (Graseby Ionics, now Smiths Detection, UK).
  • the vapour concentration in the bulk air stream has not been accurately quantified but is estimated to be 0.04 mg m "3 .
  • the total flow rate is maintained at 400 ml min "1 and a cell temperature of 35°C.
  • low molecular weight solvents also affect the field dependency of the DMMP monomer ion, as can be seen by comparing Figures 3, 4, 5 and 6.
  • Each low molecular weight solvent which is referred to as a modifier when used at high concentration, as opposed to a dopant when used at low concentration (0.1 to 1 ppm), has a unique effect on the field dependency. Ethanol has the most pronounced effect. The magnitude of the effect is also modifier concentration dependent. However, if the same concentration of modifier is routinely used for HiFAWS analysis then the reliability of the analysis, over that of an analysis that is dependent on an unknown concentration of water, is vastly improved.
  • GA and GB could also be discriminated from each other, and a known inlerferent chemical, in the presence of 200 ppm propan-2-ol and 800 ppm water at an applied RF potential of 1200 V. There is good discrimination between the reactant ion, monomer cluster ion and dimer cluster ion. Discrimination was increased at an RF potential of 1400 V. Mass spectra for the GA and GB monomer peaks showed evidence of GA clustering with up to three propan-2-ol molecules and GB with up to four propan-2-ol molecules. The spectra showed little evidence of water clustering even at a water concentration of 800 ppm.

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  • Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Analytical Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Electrochemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Other Investigation Or Analysis Of Materials By Electrical Means (AREA)

Abstract

La présente invention concerne des procédés améliorés permettant d’identifier des molécules cibles par spectrométrie à forme d’onde asymétrique en champ intense (HiFAWS). En particulier, le procédé élimine de manière sensible l’effet de l’eau sur la dépendance au champ des ions des molécules cibles, par l'utilisation de gaz porteurs comprenant un solvant de faible masse moléculaire possédant t une affinité pour les protons supérieure à celle de l'eau.
PCT/GB2009/001258 2008-05-30 2009-05-15 Procédés améliorés pour spectrométrie à forme d’onde asymétrique en champ intense (hifaws) Ceased WO2009144443A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
GB0809867.5 2008-05-30
GB0809867A GB0809867D0 (en) 2008-05-30 2008-05-30 Improved methods for high field asymmetric waveform spectrometry (HIFAWS)
GB0816411A GB0816411D0 (en) 2008-09-09 2008-09-09 Improved methods for high field asymmetric waveform spectrometry (HiFAWS)
GB0816411.3 2008-09-09

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Publication Number Publication Date
WO2009144443A1 true WO2009144443A1 (fr) 2009-12-03

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002071053A2 (fr) * 2001-03-05 2002-09-12 The Charles Stark Draper Laboratory, Inc. Procede et dispositif de chromatographie couplee a la spectrometrie de mobilite ionique a forme d'onde asymetrique a champ eleve (faims)
US20050040330A1 (en) * 2001-06-30 2005-02-24 Kaufman Lawrence A. System for DMS peak resolution

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7005632B2 (en) * 2002-04-12 2006-02-28 Sionex Corporation Method and apparatus for control of mobility-based ion species identification
US7129482B2 (en) * 1999-07-21 2006-10-31 Sionex Corporation Explosives detection using differential ion mobility spectrometry
US7399958B2 (en) * 1999-07-21 2008-07-15 Sionex Corporation Method and apparatus for enhanced ion mobility based sample analysis using various analyzer configurations
CA2493608A1 (fr) * 2002-07-25 2004-02-05 Sionex Corporation Procede et appareil pour une commande d'identification d'especes ioniques, fondee sur la mobilite

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2002071053A2 (fr) * 2001-03-05 2002-09-12 The Charles Stark Draper Laboratory, Inc. Procede et dispositif de chromatographie couplee a la spectrometrie de mobilite ionique a forme d'onde asymetrique a champ eleve (faims)
US20050040330A1 (en) * 2001-06-30 2005-02-24 Kaufman Lawrence A. System for DMS peak resolution

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
LEVIN D S; VOUROS P; MILLER R A; NAZAROV E G; MORRIS J C: "Characterization of gas-phase molecular interactions on differential mobility ion behavior utilizing an electrospray ionization-differential mobility-mass spectrometer system", ANALYTICAL CHEMISTRY 20060101 AMERICAN CHEMICAL SOCIETY US, vol. 78, no. 1, 1 January 2006 (2006-01-01), pages 96 - 106, XP002546253 *

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GB2459580A (en) 2009-11-04
GB0908473D0 (en) 2009-06-24

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