Mass spectrometer method and apparatus for monitoring for TATP
Methods and apparatus for monitoring air samples for the presence of the explosive TATP are disclosed. A preferred approach employs proton transfer reaction mass spectrometry PTR-MS). The system may be operated continuously on a real time or near real time basis. A delivery tube of specific dimensions and materials is employed to introduce the sample into the ionization chamber which in turn generates the ions which are delivered to the mass spectrometer for determining the m/z values. The system may employ a plurality of ionization chambers to reduce the amount of false negative identifiers. A multiple inlet ion funnel may be employed to combine the ions from each of the ionization chambers. Chemical ionization may be employed. A validation module may be employed to reduce the amount of false positive identifiers.
1. A method of monitoring a sample for TATP while simultaneously monitoring for other materials comprising
providing a delivery tube for delivering air as said sample to an instrument,
providing said instrument with a plurality of ionization chambers, each receiving an equal portion of said sample,
said ionization chambers being structured to receive said sample from said delivery tube,
delivering equal portions of said sample under different ionization conditions to each said ionization chamber,
subjecting said sample portions to a proton-transfer reaction to generate ions which protonate target materials within said sample,
combining said portions into a single stream,
delivering said single stream of protonated ions to a mass spectrometer for determination of the m/z value,
discharging the ion protonated residual sample from said ionization chambers to the atmosphere,
if the mass spectrometer provides a reading of one of 223 and 240 for parent ions and 91 for fragments determining that TATP is present in the sample,
performing said method continuously during said monitoring, and
employing a verification cycle.
2. The method of claim 1 including
said delivery tube having a sampling tube having a length of about 5 to 200 feet, and
said sampling tube having an outer diameter of about ¼ to ½ inch.
3. The method of claim 2 including
a flow rate of said sample through said sampling tube being about 0.1 to 25 liters per minute.
4. The method of claim 3 including
the rate of flow of said sample through delivery tube being about 7 to 10 liters per minute.
5. The method of claim 2 including
the flow rate of said sample through said delivery tube being about 0.1 to 0.5 liters per minute.
6. The method of claim 2 including
not heating said delivery tube.
7. The method of claim 2 including
said delivery tube having an inlet tube having an outer diameter of about 1/16 to ⅛ inch.
8. The method of claim 2 including
said delivery tube being internally coated.
9. The method of claim 2 including
said delivery tube being composed of inert material.
10. The method of claim 2 including
said delivery tube having a sampling tube having a length of about 100 to 200 feet.
11. The method of claim 1 including
employing two said ionization chambers.
12. The method of claim 1 including
employing a multiple inlet ion funnel to combine said ions for TATP and said other materials before they enter said mass spectrometer.
13. The method of claim 12 including
processing said sample for different compounds in different said ionization chambers.
14. The method of claim 12 including
individually controlling the internal pressure, temperature and voltage for each of said ionization chambers.
15. The method of claim 1 including
heating said ionization chamber up to about 105° C.
16. The method of claim 15 including
heating said ionization chamber to about 80° C. to 120° C.
17. The method of claim 16 including
said heating of said ionization chambers being to about 95° C. to 105° C.
18. The method of claim 1 including
performing said monitoring on a real time basis.
19. The method of claim 18 including
performing said monitoring in increments between about 0.8 and 1.2 seconds.
20. The method of claim 1 including employing chemical ionization to reduce fragmentation of the molecules during ionizing.
21. The method of claim 1 including
processing fragments of said sample formed during said protonation of said sample by said mass spectrometer, and
employing the output of said mass spectrometer from said fragments in identifying the sample.
22. The method of claim 21 including
if said mass spectrometer provides a reading of 223 for the parent ions and 91 for the parent fragments determining that TATP is present in the sample.
23. The method of claim 21 including
if the said mass spectrometer provides a reading of 240 for the parent ions and 91 for the parent fragments determining that TATP is present in the sample.
24. The method of claim 1 including
employing in-situ a validation cycle by processing a second portion of said sample in one of said ionization chambers under the same ionization conditions.
25. The method of claim 24 including
employing said validation cycle when said mass spectrometer provides a positive output indicating the presence of TATP.
26. The method of claim 24 including
separating said second portion from said delivery tube before introduction into said ionization chamber.
27. The method of claim 24 including
storing said second portion of said sample.
28. The method of claim 27 including
effecting said storage of said second portion in a storage unit selected from the group consisting of air canisters, bags and desorption tubes.
29. The method of claim 1 including
said sampling tube is composed of an inert material.
30. The method of claim 29 including
said delivery tube is made of a material selected from the group consisting of perfluoroalkoxy and polyether-ether-ketones.
31. The method of claim 1 including
employing a vacuum pump to bring said sample into said ionization chamber.
32. The method of claim 1 including
employing suction from said ionization chambers to bring said sample into said ionization chambers.
33. The method of claim 1 including
said delivery tube having a sampling tube having a length of about 100 to 200 feet.
34. The method of claim 1 including
said ionization chambers operating at a voltage of about 150 to 650 volts.
35. The method of claim 34 including
said ionization chamber operating at a voltage of about 215 to 235 volts.
36. The method of claim 1 including
employing pressure within said ionization chamber of about 2 to 4 mbar.
37. The method of claim 36 including
employing pressure within said ionization chamber of about 2.1 to 2.3 mbar.
38. Apparatus for monitoring a sample for TATP while monitoring for other materials comprising
a delivery tube for delivering a sample,
employing a plurality of said ionization chambers each receiving an equal portion of said sample and being operably associated with said delivery tube for receiving said sample therefrom and creating ions therefrom,
said ionization chambers being structured to subject said equal portions of said sample to chemical ionization to protonate target materials within said sample under different ionization conditions for each said ionization chamber and to combine said portions into a single stream,
a mass spectrometer for receiving said single stream protonated ions from each said ionization chamber and determining the m/z for said sample,
said mass spectrometer is structured to provide a reading of m/z values which is one of 223 and 240 and a fragment value of 91 when TATP is present in said sample, and
said apparatus being structured perform continuously during said monitoring.
39. The apparatus of claim 38 including
said apparatus being structured to process a sample which is air.
40. The apparatus of claim 38 including
said delivery tube having a sampling tube of a length of about 100 to 200 feet.
41. The apparatus of claim 38 including
a multiple inlet ion funnel for combining the ions from each said ionization chamber before they enter said mass spectrometer.
42. The apparatus of claim 41 including
said ionization chambers being structured to individually control internal pressure, temperature and voltage for each of said ionization chamber.
43. The apparatus of claim 38 including
said apparatus being structured to provide real time monitoring.
44. The apparatus of claim 43 including
performing said monitoring on a real time basis in increments of about 0.8 to 1.2 seconds.
45. The apparatus of claim 38 including
said delivery tube having a sampling tube having a length of about 5 to 200 feet.
46. The apparatus of claim 45 including
said delivery tube being composed of an inert material.
47. The apparatus of claim 46 including
said delivery tube is made of a material selected from the group consisting of perfluoroalkoxy and polyether-ether-ketones.
48. The apparatus of claim 46 including
said sampling tube having an outer diameter of about ¼ to ½ inch.
49. The apparatus of claim 48 including
said delivery tube having an outer diameter of about ⅜ to ½ inch.
50. The apparatus of claim 38 including
a validation unit for processing another portion of said sample to confirm the accuracy of the result obtained from the original portion of said sample, and
said validation unit having a storage sample loop for storing a said portion of said sample.
51. The apparatus of claim 50 including
said apparatus having a storage container for storing a portion of said sample.
52. The apparatus of claim 51 including
said storage container being selected from the group consisting of air canisters, bags and desorption tubes.
53. The apparatus of claim 38 including
said delivery tube structured to deliver said sample to said ionization chambers under the influence of a vacuum pump.
54. The apparatus of claim 38 including
said delivery tube being composed of a material selected from the group consisting of perfluoroalkoxy and polyether-ether-ketones.
55. The apparatus of claim 38 including
said apparatus structured to provide a sample flow rate of about 0.1 to 25 liters per minute.
56. The apparatus of claim 55 including
said apparatus structured to provide a sample flow rate of about 7 to 10 liters per minute.
57. The apparatus of claim 38 including
said apparatus structured to heat said ionization chambers, and
said apparatus structured to heat said ionization chamber to about 95 to 105° C.
58. The apparatus of claim 57 including
said apparatus structured to provide an applied voltage to the ionization chambers of about 150 to 650 volts.
59. The apparatus of claim 38 including
said apparatus structured to employ the ionization chambers internal vacuum system to draw the sample into the ionization chamber without requiring the use of a separate vacuum pump.
60. The apparatus of claim 38 including
said apparatus structured to apply vacuum within said ionization chambers of about 2 to 4 mbar.