Post on 15-Dec-2015
Technology Transition Workshop
DART and Trace Evidence(a bag of tricks for using DART)
Robert B. Cody
JEOL USA, Inc.
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
Technology Transition Workshop
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
Technology Transition Workshop
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
Technology Transition Workshop
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
Technology Transition Workshop
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
Technology Transition Workshop
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
Technology Transition Workshop
Volatiles, headspace: some applications
• Arson accelerants• Residual solvent vapors• Odors• Liquors• Residual tear gas ?
Technology Transition Workshop
Volatiles, headspace: methods
1. Direct analysis
2. Adsorbant (e.g. Tenax), thermal desorption
3. Solid-phase microextraction
Technology Transition Workshop
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
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
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
Technology Transition Workshop
3. Volatiles, headspace: SPME
• Fiber coated with extractive phase (e.g. PDMS)
• Selective phases• Compatible with GC/MS, DART, LC/MS
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)
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
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
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
Technology Transition Workshop
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
Technology Transition Workshop
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
Technology Transition Workshop
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
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
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
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
Technology Transition Workshop
Real (top) vs. Counterfeit Marlboro Brand Cigarette
Volatile trace components are different
Nicotine
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
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
Technology Transition Workshop
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
Technology Transition Workshop
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.
Technology Transition Workshop
Polymers
Nylon 6poly(caprolactam)
Polyethylene terephthalate
Technology Transition WorkshopPittCon Carpet 2006
Technology Transition Workshop
PittCon Carpet Polymer = Nylon 6
Match:Nylon 6
Technology Transition Workshop
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)
Technology Transition Workshop
(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.
Technology Transition Workshop
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
Technology Transition Workshop
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
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?
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)
Technology Transition Workshop
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]+
Technology Transition Workshop
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
Technology Transition Workshop
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
Technology Transition Workshop
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
Technology Transition Workshop
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
Technology Transition Workshop
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
Technology Transition Workshop
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
Technology Transition Workshop
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
Technology Transition Workshop
Thank you!