Christopher Parker - Module 12, Mass Spectrometry.02.doc Page 1 

Training Guidelines for the Fire Debris Analyst 

Lesson Plan (Module) 12 

Date: December 2004 Instructor: Qualified Instructor 

Subject: Mass Spectrometry Total Time: 12 hours 

Learning Objectives 

3⁄4 Demonstrate a basic understanding of how a mass spectrometer operates 

(instrumentation). 

3⁄4 Demonstrate a basic understanding of mass spectrometry theory. 

3⁄4 Describe selected ion monitoring and how extracted ions are selected. 

3⁄4 Demonstrate how to properly interpret mass spectral data. 

Suggested Reading 

1. Arson Analysis by Mass Chromatography, Smith, R.M., Analytical Chemistry, 

Vol. 54 (13), pages 1399A-1409A, 1982. 

2. Mass Chromatograpic Analysis of Arson Accelerants, Smith, R.M., Journal of 

Forensic Sciences, Vol. 28 (2), pages 318-329, 1983. 

3. Recent Advances Toward the Detection of Accelerants in Arson Cases, Holzer, 

C., Bertsch, W., American Laboratory, pages 15-19, Dec. 1988. 

4. Gas Chromatography-Mass Spectroscopy of Simulated Arson Debris Using 

Gasoline as an Ignitable liquid, Mach, M.H., Journal of Forensic Sciences, Vol. 

22 (2), pages 348-357, 1977. 

5. Accelerant Identification in Fire Debris by Gas Chromatography/Mass 

Spectrometry Techniques, Kelly, R., Martz, R., Journal of Forensic Sciences, Vol. 

29 (3), pages 714-727, 1984. 

6. “Automated Sampling and Computer Assisted Identification of Hydrocarbon 

Accelerants," Tontarski, R., Strobel, R., Journal of Forensic Sciences , Vol. 27 

(2), pages 710-714, 1982. 

7. Arson Analysis by Mass Spectrometry, Chapter 5, Forensic Mass Spectrometry, J. 

Yinon (Ed.), CRC Press, Inc., Boca Raton, FL, pages 131-159, 1987. 

8. GC/MS Data from Fire Debris Samples: Interpretation and Applications, Wallace, 

J.R., Journal of Forensic Sciences, Vol. 44 (5), pages 996-1012, 1999. 

9. Detection of Petroleum-Based Accelerants in Fire Debris by Target Compound 

Gas Chromatograph/Mass Spectroscopy, Keto, R.O., Wineman, P.L., Analytical 

Chemistry, Vol. 63, pages 1964-1971, 1991. 

10. An Accelerant Classification Scheme Based on Analysis by Gas 

Chromatography/Mass Spectrometry (GC-MS), Nowicki, F.F., Journal of 

Forensic Sciences, Vol. 35 (5), pages 1064-1086, 1990. 
Christopher Parker - Module 12, Mass Spectrometry.02.doc Page 2 

11. A GC-MS Database of Target Compound Chromatograms for the Identification of 

Arson Accelerants, Lennard, C.J., Rochaix, V.T., Margot, P., Science and Justice, 

Vol. 35 (1), pages 19-30, 1995. 

12. ASTM E 1618.,Standard Guide for Identification of Ignitable Liquid Residues in 

Extracts from Fire Debris Samples by Gas Chromatography-Mass Spectrometry. 

13. GC-MS Guide to Ignitable Liquids, Newman, Reta, Gilbert M. and Lothridge, K., CRC 

Press, 1998. 

Introduction 

This lesson covers the theoretical basis of mass spectrometry and its application to the 

analysis of ignitable liquids and other materials. 

Outline 

1. Mass Spectrometer 

a. Comparison of GC detectors 

i. strengths and weaknesses 

ii. sensitivity 

iii. resolving power 

b. Components 

i. vacuum systems 

ii. GC/MS interfaces 

iii. electron impact ionization 

iv. chemical ionization 

v. mass separation methods 

- quadrupole 

- ion trap 

- magnetic sector 

- time of flight 

- MS/MS 

vi. detection/ion abundance determination 

c. Operation and maintenance 

i. tuning and calibration 

ii. routine maintenance 

2. Basic Interpretation of Mass Spectral Data 

a. TIC 

b. Molecular ions 

c. Base peaks 

d. Nitrogen rule 

e. Isotopic ratios 

f. Fragmentation 

g. Evaluation of the quality of mass spectral data 
 

Christopher Parker - Module 12, Mass Spectrometry.02.doc Page 3 

h. Libraries 

3. Selected Ion Monitoring 

a. Chemical structure review 

i. alkanes 

ii. alkenes 

iii. aromatics 

iv. naphthalenes 

v. polynuclear aromatics 

vi. indanes and indenes 

vii. styrenes 

viii. terpenes 

b. Extracted ions 

i. selection of ions to monitor 

ii. use of ratios 

c. Comparison to standards and references 

4. Sample Matrix Effects 

a. “filtering” out interfering compounds 

b. microbial degradation in soil 

c. pyrolysis of polyethylene and other plastics 

d. wood thermal degradation 

Teaching Aids 

Handout 

PowerPoint presentation 

Exercises 

Summary 

Mass spectrometry, when interfaced with gas chromatography is a powerful and valuable 

analytical tool for identifying ignitable liquids, whether they are single component 

product or complex mixtures of hydrocarbons. The technique is sensitive and 

discriminating, capable of offering a level of data not available by other GC detection 

systems. Mass spectrometry offers the additional advantage of being able to “filter” out 

pyrolysis products or other interfering compounds. 

Test Questions 
 

 

Christopher Parker - Module 12, Mass Spectrometry.02.doc Page 4 

1. A mass spectrometer is one of several available detectors for a gas 

chromatograph. True or False 

2. Electron impact is the predominant form of ionization for fire debris analytes. 

True or False 

3. A fundamental understanding of mass spectrometry theory is not needed for 

evaluation of mass spectral data. True or False 

4. Alcohols and other very volatile compounds are not detected by GC-MS. 

True or False 

5. The ratio of alkanes to aromatics can become important in evaluating mass 

spectral data. True or False 

6. Extracted ions for aromatic compounds typically include 

a. 43, 57, 71, 85 

b. 55, 69, 83 

c. 91, 105, 119 

d. 128, 142, 156 

7. Extracted ions for alkenes/cycloalkanes typically include 

a. 43, 57, 71, 85 

b. 55, 69, 83 

c. 91, 105, 119 

d. 128, 142, 156 

8. An instrument library match of a mass spectrum is adequate for identifying a 

liquid. True or False 

9. The presence of terpenes in a sample can significantly interfere with the 

interpretation of an extracted ion profile. True or False 

10. The presence of toluene, ethylbenzene and xylenes in a sample is a sure indication 

of gasoline. True or False