Method and apparatus for ion mobility spectrometry

Abstract

Molecular ions are generated by ionization, said molecular ions are accumulated in an ion reservoir that is external to the drift chamber. Than said molecular ions are dissociated into fragment ions (i.e. fragmented ions) with electromagnetic radiation or electron beams or ion beams, and said fragment ions are ion-mobility spectrometrically analyzed. In an embodiment the apparatus comprises additionally a virtual impactor and a pyrolyzer. The process of fragmentation over time are detected and analyzed, and this information is used for the differentiation of hazardous biological samples from non-hazardous biological samples.

1 . A method for ion-mobility spectrometry of a sample, comprising the steps of: 
 (a) generating molecular ions by ionization and accumulating said molecular ions in an ion reservoir that is external to a drift chamber of an ion-mobility spectrometer;    (b) exposing said molecular ions in said ion reservoir to a source of energy for a time sufficient for dissociation of said ions into fragment ions prior to ion-mobility analysis in the drift chamber of the ion-mobility spectrometer, wherein said exposing results in production of multiple charge states of fragment ions.    (c) generating molecular ions from sample molecules by ionization;    (d) accumulating said molecular ions in the ion reservoir that is external to the drift chamber;    (e) applying more than two gating pulses and performing more than two ion-mobility measurements over a certain period of time in which sample ions and/or fragment ions interact with each other before a new sample is injected into an ionization chamber; and    (f) using the occurrence of said interactions for the analysis of ion-mobility spectra.    
   
   
       2 . The method of  claim 1 , wherein biological material of the sample is pyrolyzed in a pyrolyzer prior to analysis in said ion-mobility spectrometer and different concentrations of a chemical are added to the sample prior to entering the drift chamber of said ion mobility spectrometer and said added chemical interacts with sample molecules and/or sample ions and/or fragment ions which causes transitions of the ion mobility spectra and the spectra and said transitions of spectra are used for the characterization of the sample.  
   
   
       3 . The method of  claim 2 , wherein said chemical addition is HCl.  
   
   
       4 . The method of  claim 2 , wherein said chemical addition is ammonia.  
   
   
       5 . An apparatus for ion mobility spectroscopy, comprising the parts of: 
 (a) a virtual impactor;    (b) a pyrolyzer; and    (c) a ion mobility spectrometer, wherein generated ions of said sample are fragmented into fragment ions with one of electromagnetic radiation, electrons, and with ions, and said fragment ions are detected and analyzed.    
   
   
       6 . The apparatus of  claim 5 , wherein said detected and analyzed fragment ions are arrived at by using the measurement of transitions of ion-mobility spectra due to fragmentation for the distinction of different samples.  
   
   
       7 . The apparatus of  claim 5 , wherein said virtual impactor selects particles within a size range that lies between about 0.1 μm and about 20 μm.  
   
   
       8 . The apparatus of  claim 5 , wherein said pyrolyzer is operated at a temperature between about 300° C. and about 400° C.  
   
   
       9 . The apparatus of  claim 5 , wherein said electromagnetic radiation comprises one of UV light, VUV light, and infrared light.  
   
   
       10 . The apparatus of  claim 5 , wherein the generation of ions of the sample in said ion-mobility spectrometer is achieved using a radioactive source comprises one of  3 H,  53 Ni,  241 Am, UV light, VUV light, an electrical discharge, a corona discharge and electrospray.  
   
   
       11 . The apparatus of  claim 5 , further comprising means for generating molecular ions by ionization, said ionization comprising an ionization of inert-gas molecules of said ion-mobility spectrometer and clustering of inert-gas ions with sample molecules or sample-molecule clusters or sample-molecule fragments.  
   
   
       12 . The apparatus of  claim 5 , wherein said ion-mobility spectrometer includes a drift chamber with a length between about 40 cm and about 60 cm.  
   
   
       13 . The apparatus of  claim 5 , further comprising a gas chromatograph.  
   
   
       14 . The apparatus of  claim 13 , wherein select output of the pyrolyzer are transferred to said gas chromatograph.  
   
   
       15 . The apparatus of  claim 5 , further comprising a mass spectrometer.  
   
   
       16 . The apparatus of  claim 15 , wherein said mass spectrometer operates in parallel with the ion mobility spectrometer.  
   
   
       17 . The apparatus of  claim 15 , wherein said mass spectrometer operates in series with the ion mobility spectrometer.  
   
   
       18 . The apparatus of  claim 5 , wherein said analyzed fragment ions occurs in differentiation between hazardous and non-hazardous samples.  
   
   
       19 . The apparatus of  claim 5 , wherein the substance which is analyzed ion-mobility spectrometer is pyrolyzed bioweapons-grade material.  
   
   
       20 . The apparatus of  claim 5 , wherein the substance which is analyzed ion-mobility spectrometer is a pathogen.  
   
   
       21 . The apparatus of  claim 5 , wherein biological material of the sample is pyrolyzed prior to analysis in said ion-mobility spectrometer and different concentrations of a chemical are added to the sample prior to entering the drift chamber of the ion mobility spectrometer and said added chemical interacts with one of sample molecules, sample ions, and fragment ions, which causes transitions of the ion mobility spectra and the spectra and said transitions of spectra are used for the characterization of the sample.  
   
   
       22 . The apparatus of  claim 21 , wherein said chemical addition comprises one of HCl and ammonia.  
   
   
       23 . The apparatus of  claim 5 , further comprising means for detection of micrometer-sized and sub micrometer-sized particles, said means further comprising: 
 (a) means for generating particle ions by ionization;    (b) means for extracting gas from the drift chamber in such a way that the movement of said particle ions towards the collector in the drift chamber of said ion-mobility spectrometer is increased; and    (c) means for measuring and analyzing the collector current generated by particle ions.    
   
   
       24 . The apparatus of  claim 23 , wherein said particles comprise bioweapons-grade material.  
   
   
       25 . The apparatus of  claim 23 , wherein said particles have sizes between about 100 nm and about 10 μm.  
   
   
       26 . The apparatus of  claim 23 , wherein said particles have sizes between about 2 μm and about 10 μm.  
   
   
       27 . The apparatus of  claim 23 , wherein said particles are bioweapons-grade micrometer-sized particles with attached spores or viruses.  
   
   
       28 . The apparatus of  claim 23 , wherein said particles are bioweapons-grade silicate particles with attached spores or viruses.  
   
   
       29 . The apparatus of  claim 23 , wherein said particles consist of inorganic compounds that are partially coated with organic compounds.  
   
   
       30 . The apparatus of  claim 23 , wherein said means for generating further comprises a radioactive source comprising one of  3 H,  53 Ni,  241 Am, UV light, VUV light, an electrical discharge, a corona discharge, and electrospray.  
   
   
       31 . The apparatus of  claim 23 , wherein said means for generating further comprises means for an ionization of inert-gas molecules of said ion-mobility spectrometer and clustering of inert-gas ions with said particles.  
   
   
       32 . The apparatus of  claim 5 , further comprising a drift chamber having an electric field with a strength between about 50 V/cm and about 5000 V/cm.  
   
   
       33 . The apparatus of  claim 5 , further comprising a drift chamber having an electric field applied by more than 5 electrodes or guard rings.  
   
   
       34 . The apparatus of  claim 5 , further comprising: 
 (a) an ionization chamber for the generation of particle ions by ionization; and    (b) drift chamber and collector; wherein a pump extracts gas from the drift chamber in such a way that the movement of said particle ions towards the collector in the drift chamber is increased, a collector current generated by particle ions is measured, and a spectrum of particle ions is used for detection and characterization of micrometer-sized particles.    
   
   
       35 . The apparatus of  claim 5 , further comprising at least one filter in place of said virtual impactor.