Ion Mobility Spectrometry Determination of Rates of Decomposition of Ions of Explosives: The Build and the Qualification

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1 Ion Mobility Spectrometry Determination of Rates of Decomposition of Ions of Explosives: The Build and the Qualification G.A. Eiceman, X. An, J.A. Stone 1 Department of Chemistry and Biochemistry, New Mexico State University, Las Cruces, NM 1 Department of Chemistry, Queens University, Kingston, Ontario Canada CRITICAL TECHNOLOGY

2 ...AND RESPONSIBLE KNOWLEDGE PROPERTIES OF EXPLOSIVES Molecular Weight Melting Point Vapor Pressure Decomposition Temperature Thermal ignition temperature Crystal density Energy of formation Enthalpy of formation Detonation Velocity Strength and Brisance values On gas ions....nothing

3 CRITICAL STEP IN IMS AND APCI MS The formation of product ions M O 2- (H 2 O) n [M O 2- (H 2 O) n ]* - CRITICAL STEP IN IMS AND APCI MS The life-times of ions M O 2- (H 2 O) n [M O 2- (H 2 O) n ]* _ k for _ - k rev If k rev > k for then no response observed

4 HOW TO MEAURE ION LIFETIMES BY OBSERVING DEPENDENCE ON HEAT OR ENERGY [M O 2- (H 2 O) n ]* _ - Energy Thermal ions with IMS Heated ions with High Field by DMS ION KINETICS BY IMS 291 K Relative Intensity 287 K 283 K 277 K Drift Time (ms)

HEAT OF DISSOCIATION OF PBD 7 6 ln k 5 4 3 3.4 3.6 3.8 4 4.

5 HEAT OF DISSOCIATION OF PBD 7 6 ln k /T(K K Relative Intensity 287 K 283 K 277 K Drift Time (ms)

6 PROPYL ACETATE IN AT 300 V/cm and const residence time Di t butyl pyridine drift time used to adjust E for constant residence time in drift region PROPYL ACETATE IN AT 300 V/cm and const residence time

7 Ion Abundance Mass, Da CANNOT QUANTITATIVELY ASSIGN ION INTENSITY DUE TO SOURCE-DRIFT CONNECTION

8 SOLUTION: ISOLATE SOURCE FROM DRIFT REGION BY ION SELECTION ION SHUTTER No. 1 ION SHUTTER No. 2 SOLUTION: ISOLATE SOURCE FROM DRIFT REGION BY ION SELECTION ION SHUTTER No. 1 ION SHUTTER No. 2

9 NMSU KINETIC IMS NMSU KINETIC IMS Simion simulation of the IMS

10 NMSU KINETIC IMS CRITICAL STEP IN IMS AND APCI MS [M O 2- (H 2 O) n ]* M O 2- (H 2 O) n _ - k rev _

11 CHEMISTRY OF EXPLOSIVES R.E. Ewing, G.J. Ewing, D.A. Atkinson, and G.A. Eiceman, Talanta, 2001, 54, [M - (H 2 O) n ] [M O 2 - (H2 O) n ] - - [M O 2 - (H2 O) n ]* [NO 2 - (H2 O) n ] [M Cl - (H 2 O) n ]* [(M-1) - (H 2 O) n ] MISSING IN DATA BASES ON EXPLOSIVES [M - (H 2 O) n ] k ct [M O 2 - (H2 O) n ]* k frag k ha [NO 2 - (H2 O) n ] [(M-1) - (H 2 O) n ]

12 Proton Bound Dimer of Ketone at 124 C M 2 H + E1 300V/cm E2 400V/cm S1 400us shutter width S2 400us shutter width At 150 C M 2 H + MH + E1 300V/cm E2 400V/cm S1 1ms shutter width S2 400us shutter width

13 At 166 C MH + M 2 H + E1 300V/cm E2 400V/cm S1 1ms shutter width S2 400us shutter width At 166 C with longer residence time MH + M 2 H + E1 300V/cm E2 300V/cm S1 1ms shutter width S2 400us shutter width

14 At 166 C still longer residence time MH + M 2 H + E1 300V/cm E2 200V/cm S1 1ms shutter width S2 400us shutter width SUMMARY OF STUDIES 166 C

RATES AT 161 C field (V/cm) k 10 9 cm 3 mol 1 s 1 175 0.05158 200 0.05307 225 0.05260 250 0.

15 RATES AT 161 C field (V/cm) k 10 9 cm 3 mol 1 s avg_k sd %RSD 3.396

VALIDATION OF KINETIC IMS pentanone. The enthalpy changes from NIST for the association reaction are -121, -131 amd -126 kj/mol. The first and last are by T. McMahon and the other by M. Meot-Ner.

16 VALIDATION OF KINETIC IMS pentanone. The enthalpy changes from NIST for the association reaction are -121, -131 amd -126 kj/mol. The first and last are by T. McMahon and the other by M. Meot-Ner. The associated entropy changes are, respectively, -149, -141 and -131 J/(K mol). We obtain kj/mol for E a, which can be equated to U o, as (H = U + PV) in H o = U o + (PV) = E a + (nrt) = E a + ( n)rt. For the dissociation M 2 H + MH + + M, n = 2 1 = +1. Then, taking 158 C, the midpoint of our temperature range, ( n)rt = 1 x x 431 = 3.6 kj/mol. Hence, for the dissociation reaction, H o = kj/mol. This is right in the middle of the literature values, CONCLUSIONS ON IMS 1. Plot ln k versus 1/T to obtain H and S 2. Kinetics first proven with Ketones matches literature by another method 3. DATA GOOD.ON TO EXPLOSIVES

17 ANOTHER CONCEPT FOR REDUCED FALSE ALARMS IN IMS OR MS DMS Drift Tube Fragmenter Analyzer DMS Drift Tube Fragmenter Analyzer DMS Drift Tube Fragmenter Analyzer ION DECOMPOSITION BY 1 MHz ELECTRIC FIELD Ground Top Electrode t 2 α>0 Gas Flow from Ion Source α=0 To Detect t 1 α<0 Add DC Here Bottom Electrode - + Waveform Generator Ground

18 STUDIES MADE WITH SIONEX SVAC AND NMSU DMS/MS SIONEX Corporation ELECTRIC FIELD HEATING PROPYL ACETATE AT 100 C Separation Field, Td Compensation Field (Td)

Fragmentation pathways and mechanisms of aromatic compounds in atmospheric pressure studied by GC-DMS and DMS-MS. International Journal of Mass Spectrometry 2007, 263, (2-3), 137-147.

19 Fragmentation pathways and mechanisms of aromatic compounds in atmospheric pressure studied by GC-DMS and DMS-MS. International Journal of Mass Spectrometry 2007, 263, (2-3), Shai Kendler, Gordon R. Lambertus, Barry D. Dunietz, Stephen L. Coy, Erkinjon G. Nazarov, Raanan A. Miller c and Richard D. Sacks DMS-pre-filtered time-of-flight mass spectrometry (DMS MS) has been used to verify the chemical composition of the ion species resolved by GC DMS. This work focuses on the fragmentation of diaryl compounds, including diphenyl methane (DPM) and bibenzyl (BB), using information from the DMS and DMS MS spectra of a series of aromatic compounds.. DPM H + is observed to undergo field-induced fragmentation in the DMS to produce C 7 H 7+ (Bz + ) and unobserved neutral benzene with a low energy barrier. In contrast, BB H + fragments to C 8 H 9+ and benzene with a higher energy barrier. Calculated barriers and experimental results are in qualitative agreement.... It is suggested that CID in DMS can further enhance DMS analytical performance MASS SPECTRA FROM DMS MS OF PROPYL ACETATE AT 100 C Normalized Intensity Mass-to-Charge

20 MASS ASSIGNMENT OF DMS MS OF PROPYL ACETATE AT 100 C ion mass Da Separation Field M 2 H MH + (H 2 O) n n CH 3 COOH H + (H 2 O) n n CH 3 CO + 43 MS for CID of M 2 H + (m/z 205) from DMS/MS at 100 C Mass-to-Charge

21 ELECTRIC FIELD HEATING PROPYL ACETATE AT 100 C Separation Field, Td Compensation Field (Td) GC DMS STUDIES (AVOIDING IMPURITIES) Retention Time (min) Compensation Field (Td)

22 GC DMS STUDIES (AVOIDING IMPURITIES) Retention Time (min) Compensation Field (Td) GC DMS STUDIES (AVOIDING IMPURITIES) Retention Time (min) Compensation Field (Td)

23 APPEARANCE FIELD FOR FRAGMENT IONS WITH Td AND GAS TEMPERATURE Separation Field (Td) Gas Temperature ( C) APPEARANCE FIELD FOR FRAGMENT IONS WITH Td AND GAS TEMPERATURE Separation Field (Td) Ethyl hexanoate Ethyl propionate Propyl butyate Propyl propionate Hexyl acetate Amyl acetate Butyl acetate Propyl acetate Gas Temperature ( C)

24 MASS ASSIGNMENT OF DMS MS OF PROPYL ACETATE AT 100 C Separation Field M 2 H + slow MH + (H 2 O) n fast CH 3 COOH H + (H 2 O) n MASS ASSIGNMENT OF DMS MS OF PROPYL ACETATE AT 100 C Separation Field M 2 H + MH + (H 2 O) n CH 3 COOH H + (H 2 O) n

25 CONTROL WITH METHYL ACETATE AT 100 C Retention Time (min) Compensation Field (Td) CONTROL WITH METHYL ACETATE AT 100 C Retention Time (min) Compensation Field (Td)

26 CONTROL WITH METHYL ACETATE AT 100 C Retention Time (min) Compensation Field (Td)

27 ACKNOWLEDGEMENTS JAIME RODRIGUEZ ERKIN NAZAROV Funding: URI Center for Excellence in Explosives Detection, Mitigation, and Response

DISSOCIATION OF GAS IONS IN AIR BEFORE MASS SPECTROMETERS USING ELECTRIC FIELDS FROM FIELD DEPENDENT MOBILITY SPECTROMETERS

DISSOCIATION OF GAS IONS IN AIR BEFORE MASS SPECTROMETERS USING ELECTRIC FIELDS FROM FIELD DEPENDENT MOBILITY SPECTROMETERS X. An, J.A. Stone, and G.A. Eiceman * Department of Chemistry and Biochemistry