1. Application of Comprehensive Two-Dimensional Gas Chromatography - Mass Spectrometry to Forensic Science Investigations
Glenn S. Frysinger
Richard B. Gaines
Department of Science
U.S. Coast Guard Academy
New London, Connecticut

2. U.S. Coast Guard Academy
U.S. Military Academy located in New London, Connecticut on the Thames River near Long Island Sound
Cadets earn a B.S. degree in science, engineering, government, or management.
The academic degree program & professional training prepares graduates to receive commissions in the U.S. Coast Guard
Five year service commitment

3. Application of GC × GC/MS to Forensic Science Investigations
Oil Spill Fingerprinting
Fire Debris Analysis

4. Application of GC × GC/MS to Forensic Science Investigations
GC × GC and GC × GC/MS methods are in competition with GC/MS standard methods (ASTM, EPA).

5. Oil Spill Fingerprinting – ASTM D5739
Use GC/MS to compare the chemical composition of petroleum oil spills with suspected sources.
Use GC/MS to identify and compare specific classes of compounds that are both unique descriptors of oil and resistant to environmental degradation.
Chemical analysis supports a conclusion of similar, dissimilar, or inconclusive.

6. Oil Spill Fingerprinting – ASTM D5739

7. Oil Spill Fingerprinting
Coast Guard Marine Safety Laboratory Case
Marine diesel fuel spill.
Fuel from two suspect fishing vessels in the area sampled as potential sources.
Oil Spill Fingerprinting
GC/MS TIC
Spill
(min) 5 10 15 20 25 30 35
Source A
(min) 5 10 15 20 25 30 35
Source B
(min) 5 10 15 20 25 30 35
Gaines et al., Environ. Sci. & Technol. 33 (1999)

8. Oil Spill Fingerprinting
GC/MS m/z 156
C2-Naphthalenes
GC/MS m/z 170
C3-Naphthalenes
Spill
Source A
Source B

9. Spill Source A Source B GC × GC – FID, Rotating Thermal Modulator
Carbon number 13 14 15 16 17 18 19 20
Gaines et al., Environ. Sci. & Technol. 33 (1999)

10. C2N C3N C4N Spill Source A Source B
GC × GC – FID, Rotating Thermal Modulator
Spill
C2N
C3N
C4N
Source A
Source B
Carbon number 13 14 15 16 17 18 19 20
Gaines et al., Environ. Sci. & Technol. 33 (1999)

11. Observations
The patterns in GC × GC images are equal to multiple GC/MS extracted ion chromatograms.
Visual analysis of GC × GC images enables rapid identification of similarities and differences between samples.
Integration of GC × GC images permits quantitative description of similarities and differences between samples.

12. Fire Debris Analysis – ASTM E1618
Use GC/MS to identify ignitable liquids (single compounds, or petroleum-based formulations or distillate products).
Use GC/MS to identify the residue of ignitable liquids in fire debris samples.
GC/MS is the preferred method over GC if samples contain high background levels of substrate materials or fire-produced combustion and pyrolysis products.

13. Fire Debris is a Complex Chemical Mixture
Substrate material
Pyrolysis products
Combustion products
Ignitable liquid ?

14. Fire Debris Analysis – ASTM E1618

15. GC/MS Are these the same ? ASTM E 1618
75% Weathered Gasoline Reference chromatogram TIC 5 10 15 20 25 30 35 40 45
Time (min)
Are these the same ?
Fire Debris TIC
ASTM E 1618
NIJ0022

16. Fire Debris Analysis – ASTM E1618

17. GC/MS m/z 106 C2-Benzenes m/z 120 C3-Benzenes m/z 134 C4-Benzenes
Fire Debris EICs 5 10 15 20 25 30 35 40 45
Time (min)
Fire Debris TIC
ASTM E 1618
NIJ0022

18. GC/MS m/z 106 m/z 120 m/z 134 Gasoline Gasoline Debris Debris Gasoline
C2-Benzenes
Gasoline
m/z 120
C3-Benzenes
Gasoline
Debris 12 15
Debris
m/z 134
C4-Benzenes 15 20 25
Gasoline
Debris
ASTM E 1618 20 25 30
NIJ0022, NIJ0023

19. 105
GC/MS
120 91
Analysis of the EIC shows the presence of compounds characteristic of specific ignitable liquids
Experiment
105
120 91
Library
m/z 120
C3-Benzenes 15 20 25
NIJ0022, NIJ0023

20. 77
105
GC/MS
120
Analysis of the EIC shows the presence of compounds NOT characteristic of specific ignitable liquids
Experiment
105 O 77
120
Library
m/z 120
C3-Benzenes 15 20 25
NIJ0022, NIJ0023

21. GC/MS 51
118 ? 77
103
Analysis of the EIC shows mixtures of compounds that are unidentifiable by MS. 63 91
115
121
Experiment
m/z 120
C3-Benzenes 15 20 25
NIJ0022, NIJ0023

22. Problems with ASTM E1618
The idea that “major ions are characteristic of each compound type” is false. Truly unique ions do not exist for any target class.
Matrix compounds unrelated to target compounds for a suspected ignitable liquid can contribute to the EIC. The EIC will contain extra peaks that may or may not coelute with the target compounds.
Matrix compounds are sometimes exactly the same as the target compounds from a suspected ignitable liquid.
Mass selectivity is an insufficient second dimension.

23. GC × GC/MS TIC of Fire Debris
4.0
3.0
Time (s)
2.0
1.0
0.0 5 10 15 20 25 30 35 40
Time (min)
NIJ0006

24. GC/MS m/z 120 C3-Benzenes Experiment 15 20 25 51 118 77 103 91 63 115
121
Experiment
m/z 120
C3-Benzenes 15 20 25
NIJ0022, NIJ0023

25. GC × GC/MS TIC of Fire Debris
4.0
3.0
Time (s)
2.0
1.0
0.0 5 10 15 20 25 30 35 40
Time (min)
NIJ0006

26. 121 N
106 79
GC × GC/MS TIC
4.0
118
103 91 78 63 51
3.0
120
105 77 91
Time (s)
2.0 43 O 58 69 85
142
1.0 41 57 71
112
142
0.0 20

27. Fire Debris Analysis – ASTM E1618

28. Gasoline – Target Compound Analysis
1,3,5-trimethylbenzene
1,2,4-trimethylbenzene
1,2,3-trimethylbenzene
indan
2-methylindan
1-methylindan
1,2,4,5-tetramethylbenzene
1,2,3,5-tetramethylbenzene
5-methylindan
4-methylindan
tetrahydronaphthalene
2-methylnaphthalene
1-methylnaphthalene
2-ethylnaphthalene
1-ethylnaphthalene
1,3-dimethylnaphthalene
2,3-dimethylnaphthalene
C3Benzenes
Target compounds are often identified based on 1D retention and ratios of molecular or fragment ions.
C4Benzenes
C1Naphthalenes
C2Naphthalenes

29. GCImage screen capture
GC × GC of Fire Debris IS
NIJ0221

30. GC × GC/MS Mass Spectra 1,3,5 - trimethylbenzene
100
105 80 60 40
120 77 91 20
1,3,5 - trimethylbenzene
100
105 80 60 40
120 77 91 20
1,2,4 - trimethylbenzene
100
105 80 60 40
120 77 91 20
1,2,3 - trimethylbenzene

31. GC × GC/MS m/z 120 Extracted
GCImage screen capture
GC × GC/MS m/z 120 Extracted
m/z 120 is the molecular ion for the C3 benzene isomers

32. C3B Target Compound GC × GC/MS
GCImage screen capture
C3B Target Compound GC × GC/MS
Extract the total ion signal at all places where m/z 105 is the base peak in the mass spectrum

33. C3B Target Compound GC × GC/MS
GCImage screen capture
C3B Target Compound GC × GC/MS
Add the condition that m/z 120 abundance must be > 20% of the base peak

34. C3B Target Compound GC × GC/MS
GCImage screen capture
C3B Target Compound GC × GC/MS
Add the condition that m/z 91 must be less than 20% of the base peak

35. C3B Target Compound GC × GC/MS
GCImage screen capture
C3B Target Compound GC × GC/MS

36. GC × GC/MS Mass Spectra 2- methylindan Peak Selection Rules
100 80 60 40 20
132
117
115 91 77
2- methylindan
Peak Selection Rules
117 = base peak
115 = 2nd most abundant
132 > 10% abundant
100 80 60 40 20
132
117
115 91 77
1- methylindan
100 80 60 40 20
132
117
115 91 77
5- methylindan
100 80 60 40 20
132
117
115 91 77
4- methylindan

37. GC × GC/MS m/z 132 Extracted
GCImage screen capture
GC × GC/MS m/z 132 Extracted
m/z 132 is the molecular ion for the methylindan isomers

38. GC × GC/MS m/z 117 Extracted
GCImage screen capture
GC × GC/MS m/z 117 Extracted
m/z 117 is the base peak for the methylindan isomers

39. Methyindan Target Compound GC × GC/MS
GCImage screen capture
Methyindan Target Compound GC × GC/MS
unknown peak

40. GC × GC/MS Mass Spectra Peak Selection Rules 117 = base peak
115 = 2nd most abundant
132 > 10% abundant
100 80 60 40 20
132
117
115 91 77
dimethylstyrene
(tentative identification)

41. GC × GC/MS Mass Spectra Peak Selection Rules 117 = base peak
115 = 2nd most abundant
132 > 10% abundant
100 80 60 40 20
132
117
115 91 77
dimethylstyrene
(tentative identification)
New Peak Selection Rules
117 = base peak
115 = 2nd most abundant
115 < 60% abundant
132 > 10% abundant
100 80 60 40 20
132
117
115 91 77
2- methylindan

42. Methyindan Target Compound GC × GC/MS
GCImage screen capture
Methyindan Target Compound GC × GC/MS

43. Gasoline – Target Compound Analysis
1,3,5-trimethylbenzene
1,2,4-trimethylbenzene
1,2,3-trimethylbenzene
indan
2-methylindan
1-methylindan
1,2,4,5-tetramethylbenzene
1,2,3,5-tetramethylbenzene
5-methylindan
4-methylindan
tetrahydronaphthalene
2-methylnaphthalene
1-methylnaphthalene
2-ethylnaphthalene
1-ethylnaphthalene
1,3-dimethylnaphthalene
2,3-dimethylnaphthalene
C3Benzenes
C4Benzenes
C1Naphthalenes
C2Naphthalenes

44. GC × GC/MS Total Ion Chromatogram
GCImage screen capture
GC × GC/MS Total Ion Chromatogram IS
ASTM Standard Compounds
NIJ µg ASTM standard mix

45. GC × GC/MS Total Ion Chromatogram
GCImage screen capture
GC × GC/MS Total Ion Chromatogram
1 ng each compound on column IS
ASTM Standard Compounds
NIJ µg ASTM standard mix

46. GC × GC/MS Total Ion Chromatogram
GCImage screen capture
GC × GC/MS Total Ion Chromatogram IS
75% Weathered Gasoline
NIJ µg 75% Wx gasoline

47. GC × GC/MS Template Results
GCImage screen capture
GC × GC/MS Template Results
75% Weathered Gasoline

48. GC × GC/MS Total Ion Chromatogram
GCImage screen capture
GC × GC/MS Total Ion Chromatogram
Fire Debris
NIJ µg 75% Wx gasoline / nylon carpet matrix

49. GC × GC/MS Total Ion Chromatogram
GCImage screen capture
GC × GC/MS Total Ion Chromatogram
Nylon Matrix
NIJ0217 nylon carpet matrix

50. Fire Debris = Gasoline + Matrix
1-methylnaphthalene
Matrix
2-methylnaphthalene
Fire Debris = Gasoline + Matrix IS
Gasoline
dodecane
tetrahydronaphthalene
4-methylindan
5-methylindan
1,2,3,5-tetramethylbenzene
1,2,4,5-tetramethylbenzene
1-methylindan
2-methyindan
indan
1,2,3-trimethylbenzene
1,2,4-trimethylbenzene
1,3,5-trimethylbenzene
Peak Volume

51. GC × GC/MS Total Ion Chromatogram
GCImage screen capture
GC × GC/MS Total Ion Chromatogram
56 Peak Aromatics Template
75% Weathered Gasoline
NIJ µg 75% Wx gasoline

52. GC × GC/MS Total Ion Chromatogram
GCImage screen capture
GC × GC/MS Total Ion Chromatogram
56 Peak Aromatics Template
(46 of 56 matched)
Fire Debris
NIJ µg 75% Wx gasoline / nylon carpet matrix

53. GC × GC/MS Peak Deconvolution
GCImage screen capture
GC × GC/MS Peak Deconvolution
NIJ µg 75% Wx gasoline / nylon carpet matrix

54. Observations
GC × GC/MS offers solutions to problems inherent in the GC/MS analysis of complex fire debris samples.
Target compounds can be selected and identified in GC × GC/MS data with MS-based algorithms.
“Target Compound Chromatograms”
Target compounds can be selected and identified with templates matched by two-dimensional retention time position, and MS algorithm or MS probability.

55. What’s Next Chemometric data analysis.
Chemometric analysis with peak tables produced from GC × GC chromatograms.
Chemometric analysis with GC × GC images.
LCDR Greg Hall, April 3, 2007
Image alignment
Image normalization
PCA, PLS DA, PARAFAC

56. Acknowledgements National Institute of Justice
U.S. Coast Guard Academy
Leco
GC Image
This project was supported by Grant Number (2002-RB-052) awarded by the National Institute of Justice, Office of Justice Programs, US Department of Justice. Points of view in this document are those of the author and do not necessarily represent the official position or policies of the US Department of Justice.