Technology Transition Workshop DART and Trace Evidence (a bag of tricks for using DART) Robert B....

Technology Transition Workshop

DART and Trace Evidence(a bag of tricks for using DART)

Robert B. Cody

JEOL USA, Inc.


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


Dopants, adducts

• Some compounds don’t form MH+ or [M-H]-

• Ammonia, NH4OH useful for forming [M+NH4]+ 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


Dopant addition

DART

NH4OH, MeCl2on swab Sample

or liquid in vial with capillary into gas stream…or…

Technology Transition WorkshopExample: 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+NH4]+ if ammonium is present


Example: Aspirin

Acetaminophen[M+H]+

Aspirin[M+NH4]

+

B: Broken Tablet

A: Unbroken Tablet

Aspirin181.050400

[M+H]+

Aspirin[M+H]+

Aspirin[M+NH4]

+Caffeine195.088394

[M+H]+Acetaminophen

152.071304[M+H]+

##

#

#

#

# = aspirin fragment ion* = inactive ingredient or coating

*

*

*

#12010080 140 160 180 20060

100%

100%

12010080 140 160 180 20060

Caffeine[M+H]+

OTC Analgesic Tablet


ExplosivesClass Examples Polarity Observed Comments

Aromatic Nitro TNT, DNT, TNB Negative M-., [M-H]-, [M-NO]- Positive ions less sensitive

Other nitro, nitrosoEGDN, NG, RDX,

HMX, tetryl, PETN

Negative[M+anion]-, e.g. [M+Cl]-, [M+NO2]-,

[M+NO3]-, [M+OAc]-

Positive ions less sensitive

Peroxide TATP, HMTD Positive [M+H]+, [M+NH4]+

Ammonia, keep temperature low (< 200 degrees)

Perchlorate Negative ClO4- Hot gas (350

degrees)

Ammonium nitrate Both NH4+, NO3

-

Hydrogen peroxide Negative [M+O2]-

Very sensitive, even to headspace

vapor

Smokeless powders Positive Additives, TNT, DNT, etc. Fingerprinting

Technology Transition WorkshopExplosives detected on wipe

Name Neutral comp. Meas. Calc. Diff(u) Rel. Abund. TNT-H C7H5N3O6 226.0125 226.0100 0.0025 100.0000 HMX+Cl C4H8N8O8 331.0164 331.0154 0.0010 59.6984 RDX+Cl C3H6N6O6 257.0078 257.0037 0.0041 39.5938 PETN+Cl C5H8N4O12 350.9821 350.9827 -0.0006 14.8834 amino-DNT+Cl C7H7N3O4 232.0149 232.0125 0.0024 10.7766 Tetryl+Cl C7H5N5O8 321.9839 321.9826 0.0012 3.8259 NG+Cl C3H5N3O9 261.9713 261.9714 -0.0001 2.2762 PETN-H C5H8N4O12 315.0101 315.0060 0.0041 1.8731


Nitroglycerin on an employee’s tie 8 hours after walking through plume from construction blasting

50 100 150 200 250 300 350m/z

x 10

NO2-

NO3-

MCl-C3H5O3-

171 175 179 183 187 191 195 199 203 207 211 215 219 223 22712

55

98

O

O

O

N

N

N

O

O

OO

O

O


Volatiles, headspace: some applications

• Arson accelerants• Residual solvent vapors• Odors• Liquors• Residual tear gas ?


Volatiles, headspace: methods

1. Direct analysis

2. Adsorbant (e.g. Tenax), thermal desorption

3. Solid-phase microextraction


1. Volatiles, headspace: direct

50 100 150 200 250 300 350 400 450

m/z

50 100 150 200 250 300 350 400 450

m/z

50 100 150 200 250 300 350 400 450

m/z

Diesel fuel standard

Carpet burned with diesel

Burnt carpet(no accelerant)Scale x50


• 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


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


3. Volatiles, headspace: SPME

• Fiber coated with extractive phase (e.g. PDMS)

• Selective phases• Compatible with GC/MS, DART, LC/MS


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)

Technology Transition WorkshopPrep: SPME/DART Irish whiskey

020406080

100

Rel

. A

bu

nd

.

60 120 180 240

93.0900

EtOH dimer Direct: No SPME

0

20406080

100

Rel

. A

bu

nd

.

60 120 180 240m/z

93.0917

173.1521

201.1875

Furfural

Et-hexanoate

Et-octanoateEt-decanoate

Et-dodecanoate

Carboxen/DVB/PDMS SPME Fiber


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

Technology Transition WorkshopPolyhydroxy compoundsDerivatization with TMSI/Pyridine

• Commercially available– e.g. Pierce Tri-Sil-ZR

• 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.

15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 3827

55

83

Si

N

N

Technology Transition Workshop-Cyclodextrin

C48H80O40

UnderivatizedMW 1296.48 amyloses

24 hydroxyls24 TMS’s

100 %

Rel

. A

bu

nd

ance

2549 2619 2689 2759 2829 2899 2969 3039 3109 3179 m/z

-CD+TMSn+C3H5N2]+

n=19n=20

n=21

n=22

n=23

n=24


Aminoglycoside antibiotics

Neomycin sulfate: 7 OH’s, see 8 TMS’sKanamycin B sulfate: 6 OH’s, see 7 TMS’s

Apramycin sulfate: 6 OH’s, see 7 TMS’s

950 1000 1050 1100 1150 1200 1250

m/z

n = 7

n = 8

n = 6

n = 5

Neomycin sulfateC23H46N6O13 . 3H2SO4

[M+TMSn+H]+

See 1 extra (small) TMSfor these compounds


0

20

40

60

80

100

Re

l. A

bu

nd

an

ce

100 150 200 250 300 350

m/z

N

N

N

NH2

NH2 NH2

MelamineC3H6N6

MH+ = 127.073

127.072

Melamine detected in pet food by Teresa Vail (University of the Pacific)

6 exchangeable H’s


Melamine H/D Exchange

125 130 135 140

m/z

127.0732

125 130 135 140

m/z

134.1175

MH+

7: [D6-melamine+D]+

Melamine: with D2O

Melamine: No D2O

C3H6N6

1 23 4 5

6

Technology Transition WorkshopBT (Bacillus Thuringensis) SporesGarden Pest Control

0

50

100

Rel.

Ab

un

dan

ce

150 250 350 450 550

m/z

196.0591

DART+ / He

Heated with TMAH

MH+

Dipicolinic acid dimethyl ester

O

O

O

OCH3CH3

Spore Biomarker


Counterfeit materials

• Presence or absence of critical ingredients (e.g. active pharmaceutical ingredients)

• Differences in the presence or absence of trace impurities

Technology Transition WorkshopGenuine and Counterfeit CialisTablets

Courtesy Tony Moffat (U. London Pharmacy)

020406080

100

Rel.

Ab

un

d.

100 200 300 400 500

m/z

390.1413

020406080

100

Rel.

Ab

un

d.

100 200 300 400 500

m/z

475.2073

Sildenafil (Viagra)

Tadalafil (Cialis)Genuine

Counterfeit

Other tablet components

Technology Transition WorkshopCounterfeit 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 fromProf. Facundo Fernandez

Georgia Tech


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


Real (top) vs. Counterfeit Marlboro Brand Cigarette

Volatile trace components are different

Nicotine


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

Technology Transition WorkshopAutoDART: Promazine (Chlorpromazine I.S.)

y = 0.1839x + 0.8363

R2 = 0.9941

0

10

20

30

40

50

60

0 50 100 150 200 250 300

ppm

S /

IS

5 replicates, 7 concentrations, 250 ppb to 250 ppm, CV = 4.5%

Linear fit

0

2

4

6

8

10

12

14

0 10 20 30 40 50 60

ppm

S /

IS


Enhanced Ion Collection with Vacuum Pump

IonSense GIST ImplementationReported BMSS 9/07

DART TubePump

Orifice

GIST on AccuTOF

Technology Transition WorkshopAutoDART + GIST: Lower detection limitsChlorpromazine (Promazine I.S.)

Chlorpromazine (AutoDART, alumina) 0.1 to 1000 ppb

y = 1.1297xR2 = 0.9983

0.1

1

10

100

1000

10000

0.1 1 10 100 1000

ppb

S/I

S (

%)

Log/log plot, 6 replicates over 2 day period, 0.1 ppb to 1000 ppb

0

20

40

60

80

100

120

140

160

180

1 2 3 4 5 6 7 8 9 10

Series1

CV = 5.7%10 replicates

100 ppb


IonSense VapurTM 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.

Technology Transition WorkshopAnother 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.


Polymers

Nylon 6poly(caprolactam)

Polyethylene terephthalate

Technology Transition WorkshopPittCon Carpet 2006


PittCon Carpet Polymer = Nylon 6

Match:Nylon 6


Material ID: Latex from J&J Band-Aid

(p o lym e rs) La te x60 110 160 210 260 310 360 410 460 510 560 610 660 710 760 810

0

50

100

277.2906 C20H37

+

345.3535C25H45

+413.4145C30H53

+

481.4807C35H61

+

279.1612 C16H23O4

+

551.5575C40H71

+619.6162C45H79

+

•Searchable polymer library spectrum

•All compositions confirmed by exact masses

•C5H8 (isoprene) units

•m/z 279=Dibutyl phthalate (plasticizer)


(d a rt_p a ints) J EO L Be ig e Ura W 2273 Ea ste rn C he m -La c C o rp78 128 178 228 278 328 378 428 478 528 578 628 678

0

50

100

81

99123

149

175

187

279

297 337369

411 457549 578

600635

(d a rt_p a ints) J EO L G re e n g ra y W 4322 Ea ste rn C he m -La c C o rp .78 128 178 228 278 328 378 428 478 528 578 628 678

0

50

100

83

114

133

149

179

203227

263291

301327 371 415

443

459 503549

578 636 663

(d a rt_p a ints) J EO L W 2274 (N .E. Ta nya Fin ishe s) (EC L P o ly/ ura c he m )80 130 180 230 280 330 380 430 480 530 580 630 680

0

50

100

99

122

149

175

193

227

255

301

313

329369

411 449483

511 549 578610 641 675

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.


Condom lubricants

200 400 600 800 1000m/z m/z

Acetone anil

n=3

n=5n=7

n=9

** * * * *

** *

** * * *

* *

200 400 600 800 1000m/z

Cholestadiene

Nonoxynol-9

200 400 600 800 1000m/z m/z

Condom swab

Post-coital vaginal swab

Technology Transition WorkshopCS (Tear gas) Detected Directly on Cloth

100 200 300 400 500

m/z

[M+H]+

20 23 26 29 32 35 38 41 44 47 50 53 56 59 62 65 68 71 7418

57

96

N

N

C l

[M+H+H2O]+

[2M+H]+

2-ChlorobenzalmalononitrileCAS # 2698-41-1Formula: C10H5ClN2

189.0209

207.0311

377.0348


Other DART CI Reagents

Reagent IE (eV) P.A. (kJ/mol) Reagent Ion

Water 12.621 691 H3O+

Oxygen 12.0697 421 O2+.

Ammonia 10.070 853.6 NH4+

Nitric oxide 9.2642 531.8 NO+.

Fluorobenzene 9.20 755.9 C6H5F+.

Values from http://webbook.nist.gov


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?

Technology Transition WorkshopDifferent DART Chemistries

H3O+

[(H2O)3+H]+

[(H2O)2+H]+O2+.

0

20

40

60

80100

Rel

. A

bu

nd

.

15 20 25 30 35 40 45 50 55

He DARTO2

+ Charge Exchange

N2 DARTNO+ APCI

020406080

100

Rel

. A

bu

nd

.

20 25 30 35 40 45m/z

NO+.

[(H2O)2+H]+

[(H2O)+NH3+H]+NH4

+

H3O+ [NO+NH3+H]+N2H+

Charge exchange

Addition, charge exchange, hydride abstraction, oxidation

Technology Transition WorkshopCharge-Exchange DART

Oxygen

He* + O2 → O2+. + e- + He

O2+. + S → S+. + O2

O2 +. + S → Fragment+ + O2

+ R.

(IE of sample S < 12.07 eV)

Fluorobenzene

He* + C6H5F → C6H5F +. + e- + He

C6H5F +. + S → S+. + C6H5F

C6H5F +. + S → [Fragment]+ + C6H5F + R.

(IE of sample S < 9.2 eV)


0

20

40

60

80

100

Re

l. A

bu

nd

.

75 100 125 150 175 200 225 250 275

m/z

71

85

97 241

111 125 141 169 197

225 255273

0

20

40

60

80

100

Re

l. A

bu

nd

.

75 100 125 150 175 200 225 250 275

m/z

71

85

99

113 127 141 155 169 226183 197

0

20

40

60

80

100

Re

l. A

bu

nd

.

75 100 125 150 175 200 225 250 275

m/z

71

85

99 113 127 141 155 169 183 197 226

Normal DART Parameters

DART O2+. Charge Exchange

Electron ionization

n-Hexadecane

M+.

[M-H]+ [M-H+O]+

[M-3H+2O]+


0

20

40

60

80

100

Rel

. A

bu

nd

.

75 100 125 150 175 200 225 250 275

m/z

71 85155 169

225

226

99 113 127 141183 197

211

0

20

40

60

80

100

Rel

. A

bu

nd

.

75 100 125 150 175 200 225 250 275

m/z

71

85

99

113 127 141 155 169 226183 197

Helium 200 degrees

Helium 300 degrees

Hexadecane : Fragmentation vs. temperature


0

50

100

Rel

. A

bu

nd

.

300 325 350 375 400 425m/z

369.3542

386.3558

0

50

100

Rel

. A

bu

nd

.

300 325 350 375 400 425

369.3529

386.3551

0

50

100R

el.

Ab

un

d.

300 325 350 375 400 425

369.3528

385.3437

Normal DART:Proton Transfer

FluorobenzeneDopant

OxygenCharge Exchange

Cholesterol[M+H-H2O]+

[M-H]+

M+.

261 271 281 291 301 311 321 331 341 351 361 37146

69

92

275

H O


0

50

100

Rel.

Ab

un

d.

10 12 14 16 18 20 22 24

Time (min.)

12

3

4

5

6

7

8

9

10

1112 13

1. 1,3-Butanediol2. Decane3. 1-Octanol 4. Undecane5. Nonanal 6. 2,6-Dimethylphenol7. 2-Ethylhexanoic acid

8. 2,6-Dimethylaniline9. Methyl decanoate10. Surfynol11. Methyl undecenoate12. Dicyclohexylamine13. Methyl dodecanoate

Modified DART parametersPseudo EI spectra

GC-DART: Grob Mix TICs


0

20

40

60

80

100

Re

l. A

bu

nd

.

3 4 5 6 7 8 9 10 11 12 13

Time (min.)

0

20

40

60

80

100

Re

l. A

bu

nd

.

3 4 5 6 7 8 9 10 11 12 13

Time (min.)

0

20

40

60

80

100

Re

l. A

bu

nd

.

3 4 5 6 7 8 9 10 11 12 13

Time (min.)

1

1. 1,3-Butanediol2. Decane3. 1-Octanol 4. Undecane5. Nonanal 6. 2,6-Dimethylphenol7. 2-Ethylhexanoic acid

8. 2,6-Dimethylaniline9. Methyl decanoate10. Surfynol11. Methyl undecenoate12. Dicyclohexylamine13. Methyl dodecanoate

6 813

910,11,12

3

5

Standard DARTparametersCI spectra

GC-DART: Grob Mix TICs


0

20

40

60

80

100

Rel

. A

bu

nd

.

4 6 8 10 12 14

Time (min.)

0

20

40

60

80

100

Rel

. A

bu

nd

.

4 6 8 10 12 14

Time (min.)

Application of GC-DART: Diesel Fuel

TIC

RICm/z 71

Alkanes


Atmospheric Pressure Thermal Ionization for Inorganics & Metals

Technology Transition WorkshopAtmospheric 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

Technology Transition WorkshopLead in paint chip

0

50

100

Rel

. A

bu

nd

.

80 140 200 260 320 380 440 500 560 620 680

224.9787

264.9724

Pb+

PbOH+

Pb2(OH)3+

PbO2H3+

100 150 200 2500

20

40

60

80

100

Rel

. A

bu

nd

.

84.9135 114.9051

207.9744

224.9764

m/z

Pb+

PbOH+In+Rb+

Orifice 1=20V

Orifice 1=90V


Stainless Steel Wire

Fe+

0

20

40

60

80

100

Rel

. A

bu

nd

ance

50 60 70 80

m/z

55.9349

62.929472.9400

Cu+

FeOH+

Ga+Mn+

Cr+ Ni+

Plunger wire from PCR Pipette


Thank you!

Technology Transition Workshop DART and Trace Evidence (a bag of tricks for using DART) Robert B....

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Transcript of Technology Transition Workshop DART and Trace Evidence (a bag of tricks for using DART) Robert B....