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Technology Transition Workshop DART and Trace Evidence (a bag of tricks for using DART) Robert B. Cody JEOL USA, Inc.

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Presentation on theme: "Technology Transition Workshop DART and Trace Evidence (a bag of tricks for using DART) Robert B. Cody JEOL USA, Inc."— Presentation transcript:

1 Technology Transition Workshop DART and Trace Evidence (a bag of tricks for using DART) Robert B. Cody JEOL USA, Inc.

2 Technology Transition Workshop Outline Use of dopants with DART SPME, other methods for analyzing volatiles Derivatization and H/D Exchange Counterfeit materials Quantitative analysis Pyrolysis of polymers, materials Other DART chemistries Atmospheric pressure thermal ionization for inorganics

3 Technology Transition Workshop Dopants, adducts Some compounds don’t form MH + or [M-H] - Ammonia, NH 4 OH useful for forming [M+NH 4 ] + from polar analytes that will not form MH + –Carbonyls, peroxides Chloride, acetate, nitrate useful for forming anion adducts for compounds that will not form [M-H] - –e.g. [M+Cl] - from explosives like RDX, PETN

4 Technology Transition Workshop Dopant addition DART NH 4 OH, MeCl 2 on swab Sample or liquid in vial with capillary into gas stream…or…

5 Technology Transition Workshop Example: Organic acids (e.g. aspirin) Should normally be analyzed in negative ion mode: give abundant [M-H] - Will not normally form [M+H] + However, can form [M+H] + and [M+NH 4 ] + if ammonium is present

6 Technology Transition Workshop Example: Aspirin

7 Technology Transition Workshop Explosives ClassExamplesPolarityObservedComments Aromatic NitroTNT, DNT, TNBNegativeM -., [M-H] -, [M-NO] - Positive ions less sensitive Other nitro, nitroso EGDN, NG, RDX, HMX, tetryl, PETN Negative [M+anion] -, e.g. [M+Cl] -, [M+NO 2 ] -, [M+NO 3 ] -, [M+OAc] - Positive ions less sensitive PeroxideTATP, HMTDPositive[M+H] +, [M+NH 4 ] + Ammonia, keep temperature low (< 200 degrees) PerchlorateNegativeClO 4 - Hot gas (350 degrees) Ammonium nitrateBothNH 4 +, NO 3 - Hydrogen peroxideNegative[M+O 2 ] - Very sensitive, even to headspace vapor Smokeless powdersPositiveAdditives, TNT, DNT, etc.Fingerprinting

8 Technology Transition Workshop Explosives detected on wipe Name Neutral comp. Meas. Calc. Diff(u) Rel. Abund. TNT-H C7H5N3O HMX+Cl C4H8N8O RDX+Cl C3H6N6O PETN+Cl C5H8N4O amino-DNT+Cl C7H7N3O Tetryl+Cl C7H5N5O NG+Cl C3H5N3O PETN-H C5H8N4O

9 Technology Transition Workshop Nitroglycerin on an employee’s tie 8 hours after walking through plume from construction blasting m/z x 10 NO 2 - NO 3 - MCl - C3H5O3-C3H5O3-

10 Technology Transition Workshop Volatiles, headspace: some applications Arson accelerants Residual solvent vapors Odors Liquors Residual tear gas ?

11 Technology Transition Workshop Volatiles, headspace: methods 1. Direct analysis 2. Adsorbant (e.g. Tenax), thermal desorption 3. Solid-phase microextraction

12 Technology Transition Workshop 1. Volatiles, headspace: direct m/z m/z m/z Diesel fuel standard Carpet burned with diesel Burnt carpet (no accelerant) Scale x50

13 Technology Transition Workshop Fast and easy, but may not be best choice in looking for trace components in presence of strong interference –Concentrate the vapor (adsorbent) –Concentrate and select the sample (SPME) Direct analysis of volatiles

14 Technology Transition Workshop 2. Volatiles, headspace: trap Adsorbant, thermal desorption –Trap vapor on Tenax, heat to desorb and purge with inert gas –or place sample inside thermal desorption chamber Inject sample with gas-tight syringe He Adsorbant in heatable trap to DART

15 Technology Transition Workshop 3. Volatiles, headspace: SPME Fiber coated with extractive phase (e.g. PDMS) Selective phases Compatible with GC/MS, DART, LC/MS

16 Technology Transition Workshop SPME/DART Procedure We have had good success with DVB/Carboxen/PDMS SPME fibers (Supelco) 1. Clean SPME fiber: heat to 250 degrees C in inert gas (e.g. GC injector) 2. Expose SPME fiber to headspace or liquid solution for several minutes 3. Hold fiber in DART gas stream (250 degrees C)

17 Technology Transition Workshop Prep: SPME/DART Irish whiskey Rel. Abund EtOH dimer Direct: No SPME Rel. Abund m/z Furfural Et-hexanoate Et-octanoate Et-decanoate Et-dodecanoate Carboxen/DVB/PDMS SPME Fiber

18 Technology Transition Workshop Derivatization and reactions Derivatize to enhance volatility, count and protect labile groups like OH –Use rapid derivatization, no further cleanup H/D exchange to count exchangeable H’s –Provides some structural information –Distinguish some isomers

19 Technology Transition Workshop Polyhydroxy compounds Derivatization with TMSI/Pyridine Commercially available –e.g. Pierce Tri-Sil-Z R Simple, rapid silylation reaction. Mix with sample and heat for a few seconds (heat gun). Moisture-tolerant (use excess reagent) Count the OH’s. Only reacts with hydroxyl groups. Unreactive with thiol, amine groups. Mix, heat, analyze. No purification step needed.

20 Technology Transition Workshop  -Cyclodextrin C 48 H 80 O 40 Underivatized MW amyloses 24 hydroxyls 24 TMS’s 100 % Rel. Abundance m/z  -CD+TMS n +C 3 H 5 N 2 ] + n=19 n=20 n=21 n=22 n=23 n=24

21 Technology Transition Workshop Aminoglycoside antibiotics Neomycin sulfate: 7 OH’s, see 8 TMS’s Kanamycin B sulfate: 6 OH’s, see 7 TMS’s Apramycin sulfate: 6 OH’s, see 7 TMS’s m/z n = 7 n = 8 n = 6 n = 5 Neomycin sulfate C 23 H 46 N 6 O 13. 3H 2 SO 4 [M+TMS n +H] + See 1 extra (small) TMS for these compounds

22 Technology Transition Workshop Melamine C 3 H 6 N 6 MH + = Melamine detected in pet food by Teresa Vail (University of the Pacific) 6 exchangeable H’s

23 Technology Transition Workshop Melamine H/D Exchange MH + 7: [D 6 -melamine+D] + Melamine: with D 2 O Melamine: No D 2 O C3H6N6C3H6N

24 Technology Transition Workshop BT (Bacillus Thuringensis) Spores Garden Pest Control DART+ / He Heated with TMAH MH + Dipicolinic acid dimethyl ester Spore Biomarker

25 Technology Transition Workshop Counterfeit materials Presence or absence of critical ingredients (e.g. active pharmaceutical ingredients) Differences in the presence or absence of trace impurities

26 Technology Transition Workshop Genuine and Counterfeit CialisTablets Courtesy Tony Moffat (U. London Pharmacy) Sildenafil (Viagra) Tadalafil (Cialis) Genuine Counterfeit Other tablet components

27 Technology Transition Workshop Counterfeit Antimalarials “Yaa-chud” (Combination medicine) All these and more were analyzed in a single afternoon. Most of the time was taken up by opening the packages and keeping track of sample serial numbers. Samples from Prof. Facundo Fernandez Georgia Tech

28 Technology Transition Workshop Counterfeit Antimalarials were found to contain: Chlorpheniramine (antihistamine) Acetaminophen (analgesic) Chloroquin (older, ineffective antimalarial) Aspirin (analgesic) Chloramphenicol (antibacterial) Pyramethamine/sulfadoxin (ineffective in SE Asia) Metamizol (analgesic, may cause bone marrow disorders) Some tablets contained low levels of the active ingredient (artemisinin), presumably to fool the field tests

29 Technology Transition Workshop Real (top) vs. Counterfeit Marlboro Brand Cigarette Volatile trace components are different Nicotine

30 Technology Transition Workshop DART Quantitation Successful for liquid samples –Internal standard corrects for variations in sample positioning. Example: GHB in urine –Possibility for AWC analysis without I.S. ? –Some fully validated methods completed Semiquantitative data obtained from swabs with no internal standard Under investigation for solid samples (tablets). –Preliminary data promising

31 Technology Transition Workshop AutoDART: Promazine (Chlorpromazine I.S.) 5 replicates, 7 concentrations, 250 ppb to 250 ppm, CV = 4.5% Linear fit

32 Technology Transition Workshop Enhanced Ion Collection with Vacuum Pump IonSense GIST Implementation Reported BMSS 9/07 DART Tube Pump Orifice GIST on AccuTOF

33 Technology Transition Workshop AutoDART + GIST: Lower detection limits Chlorpromazine (Promazine I.S.) Log/log plot, 6 replicates over 2 day period, 0.1 ppb to 1000 ppb CV = 5.7% 10 replicates 100 ppb

34 Technology Transition Workshop IonSense Vapur TM Pro’s and Con’s Reduced helium consumption Better quantitative reproducibility Better detection limits for compounds with high proton affinities (stable ions in atmosphere). This includes most drugs and many compounds of forensic interest. Poorer detection limits for compounds, with lower proton affinities e.g. methyl stearate Cannot adjust DART chemistry to analyze hydrocarbons, produce odd-electron ions.

35 Technology Transition Workshop Another kind of information: Products are a mixture of components Each component adds a detail to a characteristic “fingerprint” pattern DART mass spectrum Pattern matching for materials, commercial products, polymers, adhesives, etc.

36 Technology Transition Workshop Polymers Nylon 6 poly(caprolactam) Polyethylene terephthalate

37 Technology Transition Workshop PittCon Carpet 2006

38 Technology Transition Workshop PittCon Carpet Polymer = Nylon 6 Match: Nylon 6

39 Technology Transition Workshop Material ID: Latex from J&J Band-Aid C 20 H C 25 H C 30 H C 35 H C 16 H 23 O C 40 H C 45 H 79 + Searchable polymer library spectrum All compositions confirmed by exact masses C 5 H 8 (isoprene) units m/z 279=Dibutyl phthalate (plasticizer)

40 Technology Transition Workshop 3 beige paint chips Different beige paints give different mass spectra Spectra are reproducible and a searchable library can be created Polymers and additives can be identified.

41 Technology Transition Workshop Condom lubricants Condom swab Post-coital vaginal swab

42 Technology Transition Workshop CS (Tear gas) Detected Directly on Cloth m/z [M+H] + [M+H+H 2 O] + [2M+H] + 2-Chlorobenzalmalononitrile CAS # Formula: C 10 H 5 ClN

43 Technology Transition Workshop Other DART CI Reagents ReagentIE (eV)P.A. (kJ/mol)Reagent Ion Water H3O+H3O+ Oxygen O 2 +. Ammonia NH 4 + Nitric oxide NO +. Fluorobenzene C 6 H 5 F +. Values from

44 Technology Transition Workshop Proton transfer is very useful, but it is not universal Won’t work for saturated alkanes and some other compounds Even-electron ions Can we produce odd-electron ions and mass spectra that resemble EI mass spectra?

45 Technology Transition Workshop Different DART Chemistries H3O+H3O+ [(H 2 O) 3 +H] + [(H 2 O) 2 +H] + O Rel. Abund He DART O 2 + Charge Exchange N 2 DART NO + APCI Rel. Abund m/z NO +. [(H 2 O) 2 + H] + [(H 2 O)+NH 3 + H] + NH 4 + H3O+H3O+ [NO+NH 3 +H] + N2H+N2H+ Charge exchange Addition, charge exchange, hydride abstraction, oxidation

46 Technology Transition Workshop Charge-Exchange DART Oxygen He * + O 2 → O e - + He O S → S +. + O 2 O S → Fragment + + O 2 + R. (IE of sample S < eV) Fluorobenzene He * + C 6 H 5 F → C 6 H 5 F +. + e - + He C 6 H 5 F +. + S → S +. + C 6 H 5 F C 6 H 5 F +. + S → [Fragment] + + C 6 H 5 F + R. (IE of sample S < 9.2 eV)

47 Technology Transition Workshop Normal DART Parameters DART O 2 +. Charge Exchange Electron ionization n-Hexadecane M+.M+. [M-H] + [M-H+O] + [M-3H+2O] +

48 Technology Transition Workshop Helium 200 degrees Helium 300 degrees Hexadecane : Fragmentation vs. temperature

49 Technology Transition Workshop Rel. Abund m/z Rel. Abund Rel. Abund Normal DART: Proton Transfer Fluorobenzene Dopant Oxygen Charge Exchange Cholesterol [M+H-H 2 O] + [M-H] + M +.

50 Technology Transition Workshop ,3-Butanediol 2.Decane 3.1-Octanol 4.Undecane 5.Nonanal 6.2,6-Dimethylphenol 7.2-Ethylhexanoic acid 8. 2,6-Dimethylaniline 9. Methyl decanoate 10. Surfynol 11. Methyl undecenoate 12. Dicyclohexylamine 13. Methyl dodecanoate Modified DART parameters Pseudo EI spectra GC-DART: Grob Mix TICs

51 Technology Transition Workshop 1 1.1,3-Butanediol 2.Decane 3.1-Octanol 4.Undecane 5.Nonanal 6.2,6-Dimethylphenol 7.2-Ethylhexanoic acid 8. 2,6-Dimethylaniline 9. Methyl decanoate 10. Surfynol 11. Methyl undecenoate 12. Dicyclohexylamine 13. Methyl dodecanoate ,11, Standard DART parameters CI spectra GC-DART: Grob Mix TICs

52 Technology Transition Workshop Application of GC-DART: Diesel Fuel TIC RIC m/z 71 Alkanes

53 Technology Transition Workshop Atmospheric Pressure Thermal Ionization for Inorganics & Metals

54 Technology Transition Workshop Atmospheric Pressure Thermal Ionization for Inorganics & Metals Easy way to add some qualitative inorganic analysis capabilities to system configured for DART. Use hand-held butane torch to heat samples in DART gas stream. High orifice potential breaks up clusters & adducts to maximize atomic ions. Can also use the electrospray source

55 Technology Transition Workshop Lead in paint chip Rel. Abund m/z Pb + PbOH + In + Rb + Orifice 1=20V Orifice 1=90V

56 Technology Transition Workshop Stainless Steel Wire Fe Rel. Abundance m/z Cu + FeOH + Ga + Mn + Cr + Ni + Plunger wire from PCR Pipette

57 Technology Transition Workshop Thank you!


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