OSAC 2022-S-0002 Standard 

Practice for the Analysis of 

Organic Gunshot Residue 

(OGSR) by Gas 

Chromatography-Mass 

Spectrometry (GC-MS)

Ignitable Liquids, Explosive, and Gunshot Residue Subcommittee

Chemistry: Trace Evidence Scientific Area Committee (SAC)

Organization of Scientific Area Committees (OSAC) for Forensic Science
OSAC 2022-S-0002 Standard Practice for the 

Analysis of Organic Gunshot Residue (OGSR) by Gas 

Chromatography-Mass Spectrometry (GC-MS)

2

Draft OSAC Proposed Standard

OSAC 2022-S-0002

Standard Practice for the Analysis of 

Organic Gunshot Residue (OGSR) by 

Gas Chromatography-Mass 

Spectrometry (GC-MS)

Prepared by 

Subcommittee for Ignitable Liquids, Explosive, and Gunshot Residue

Version: 1.0 - OSAC Open Comment

October 2021

Disclaimer:

This OSAC Proposed Standard was written by the [insert subcommittee or other unit name] of 

the Organization of Scientific Area Committees (OSAC) for Forensic Science following a 

process that includes an open comment period. This Proposed Standard will be submitted to a 

standards developing organization and is subject to change. 

There may be references in an OSAC Proposed Standard to other publications under 

development by OSAC. The information in the Proposed Standard, and underlying concepts and 

methodologies, may be used by the forensic-science community before the completion of such 

companion publications.

Any identification of commercial equipment, instruments, or materials in the Proposed Standard 

is not a recommendation or endorsement by the U.S. Government and does not imply that the 

equipment, instruments, or materials are necessarily the best available for the purpose.

To be placed on the OSAC Registry, certain types of standards first must be reviewed by a 

Scientific and Technical Review Panel (STRP). The STRP process is vital to OSAC’s mission of 

generating and recognizing scientifically sound standards for producing and interpreting forensic 

science results. The STRP shall provide critical and knowledgeable reviews of draft standards or 

of proposed revisions of standards previously published by standards developing organizations 
OSAC 2022-S-0002 Standard Practice for the 

Analysis of Organic Gunshot Residue (OGSR) by Gas 

Chromatography-Mass Spectrometry (GC-MS)

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(SDOs) to ensure that the published methods that practitioners employ are scientifically valid, 

and the resulting claims are trustworthy.

The STRP panel will consist of an independent and diverse panel, including subject matter 

experts, human factors scientists, quality assurance personnel, and legal experts, which will be 

tasked with evaluating the proposed standard based on a comprehensive list of science-based 

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For more information about this important process, please visit our website 

at: https://www.nist.gov/topics/organization-scientific-area-committees-forensicscience/scientific-technical-review-panels. 
OSAC 2022-S-0002 Standard Practice for the 

Analysis of Organic Gunshot Residue (OGSR) by Gas 

Chromatography-Mass Spectrometry (GC-MS)

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1 Standard Practice for the Analysis of Organic Gunshot Residue (OGSR) by Gas 

2 Chromatography– Mass Spectrometry (GC-MS)

3

4 1. Scope

5 1.1. This practice covers the analysis of organic gunshot residue (OGSR) by electron 

6 ionization-gas chromatography-mass spectrometry (GC-(EI)MS). This practice does not 

7 address the analysis of inorganic gunshot residue (IGSR) or primer gunshot residue 

8 (pGSR).

9 1.2. This practice is intended for use by competent forensic science practitioners with the 

10 requisite formal education, discipline-specific training (see Practice E2917), and 

11 demonstrated proficiency to perform forensic casework. 

12 1.3. Units – The values stated in SI units are to be regarded as the standard, unless otherwise 

13 stated.

14 1.1. This practice does not purport to address all of the safety concerns, if any, associated 

15 with its use. It is the responsibility of the user of this practice to establish appropriate 

16 safety and health practices and determine the applicability of regulatory limitations prior 

17 to use.

18

19 2. Referenced Documents

20 2.1. ASTM Standards:

21 E1588 Practice for Gunshot Residue analysis by Scanning Electron Microscopy/Energy 

22 Dispersive X-ray Spectrometry.

23 E1732 Terminology Relating to Forensic Science.

24 E2917 Practice for Forensic Science Practitioner Training, Continuing Education, and 

25 Professional Development Programs.

26 E2998 Practice for Characterization and Classification of Smokeless Powders.

27 E2999 Test Method for Analysis of Organic Compounds in Smokeless Powder by Gas 

28 Chromatography-Mass Spectrometry and Fourier Transform Infrared 

29 Spectroscopy.

30 E3255 Practice for Quality Assurance of Forensic Science Service Providers Performing 

31 Forensic Chemistry Analyses.

32 WK56998 Terminology Relating to the Examination of Explosives.

33 WK72856 Practice for the Collection and Preservation of Organic Gunshot Residue.

34

35 3. Terminology

36 3.1. For definitions of terms that can assist in interpreting this standard, refer to Terminology 

37 E1732 and WK 56998. 

38 3.2. Definitions of terms specific to this standard:

39 3.2.1. Inorganic GSR (IGSR), n – Gunshot residues from the primer, cartridge case, 

40 projectile (e.g., bullet or shot pellets), or the firearm which are typically identified 

41 using scanning electron microscope (E1588).
OSAC 2022-S-0002 Standard Practice for the 

Analysis of Organic Gunshot Residue (OGSR) by Gas 

Chromatography-Mass Spectrometry (GC-MS)

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42 3.2.2. Organic GSR (OGSR), n – Gunshot residues from the propellant and the priming 

43 mixture that are organic (carbon-based).

44 3.2.3. Primer GSR (pGSR), n – Gunshot residues generating from the priming mixture 

45 that could be inorganic or organic.

46 3.2.4. Reference Sample, n – A solution containing known target OGSR compounds.

47

48 4. Terminology

49 4.1. Gunshot residue (GSR) examination is typically performed to determine if an individual 

50 was exposed to firearm discharge. GSR analysis has historically relied upon the detection 

51 of IGSR, as described in Practice E1588, which originates primarily from the ammunition 

52 primer (pGSR). OGSR analysis provides information which complements pGSR analysis 

53 [1].

54 4.2. OGSR originates from the combustion of the smokeless powder and the priming mixture 

55 following their ignition during the firearm discharge process. After a firearm has been 

56 discharged, the combined residue can be found on exposed surfaces in the vicinity of the 

57 fired weapon (e.g., hands, other exposed skin surfaces, hair, clothing, and other surfaces). 

58 OGSR can also be found in the cartridge case after firing and can be recovered to provide 

59 information about the constituents of the propellant or the priming mixture, or both.

60 4.3. This practice is intended to be used in conjunction with a laboratory’s validated standard 

61 operating procedures.

62 4.4. This practice does not cover the interpretation or significance of the OGSR results. 

63 Laboratory specific criteria should be established and supported by data obtained during 

64 method development and validation (E3255).

65 4.4.1. Individual laboratory protocol will determine if IGSR/pGSR and GSR will be 

66 analyzed from the same sample or separate samples [2,3].

67 4.5. The analysis of intact smokeless powder grains is beyond the scope of this practice (refer 

68 to Practice E2998 and Test Method E2999).

69

70 5. Apparatus

71 5.1. Gas chromatograph (GC) – A gas chromatograph (GC) capable of using capillary columns 

72 and being interfaced to a mass spectrometer (MS) (refer to Table X1).

73 5.2. Mass Spectrometer (MS) – A mass selective detector operating in electron ionization (EI) 

74 mode and capable of acquiring mass spectra from mass-to-charge (m/z) 10 - m/z 400 with 

75 unit resolution or better.

76 5.3. Sonicator – For use when extracting OGSR components from sample items collected. 

77 5.4. Centrifuge – Recommended for use after sonication of extract and capable to achieve a 

78 minimum of 4000 RPM. Disposable centrifuge tubes that safely fit the centrifuge device 

79 are required.

80

81 6. Materials 

82 6.1. Purity of Solvents – GC-MS grade or higher.
OSAC 2022-S-0002 Standard Practice for the 

Analysis of Organic Gunshot Residue (OGSR) by Gas 

Chromatography-Mass Spectrometry (GC-MS)

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83 6.2. Analytical Solvents – Acetone, acetonitrile, ethanol, isopropanol, methanol, methylene 

84 chloride, or other appropriate solvents.

85 6.3. OGSR Standard(s) or Reference Materials – Certified reference materials are to be used. 

86 Individual reference materials or standards, or mixture thereof, may be used in place of a 

87 certified reference standard provided that they are verified before use.

88 6.3.1. The concentrations of standards or reference materials used must be above the limit 

89 of detection for the instrument to be used to analyze samples.

90 6.3.2. Concentrations of OGSR compounds recovered in forensic samples can be as low 

91 as 25 ppb [4].

92 6.4. Internal Standard – Use of an internal standard is not required for qualitative identification 

93 of OGSR but can be used to evaluate system sensitivity and reproducibility.

94 6.5. GC Carrier Gas – Helium or hydrogen of purity 99.995% or higher.

95 6.6. Drying Gas – Nitrogen, air, or other inert gas.

96 6.7. Filters – Single use disposable filters of a hydrophobic membrane construction are 

97 recommended for use to filter the extract prior to analysis. A filter membrane porosity of 

98 0.4 m or smaller is recommended. 

99

100 7. Procedure

101 7.1. Samples are submitted for OGSR analysis in one or more of the following forms: 

102 adhesive tape lifts, swabs, or vacuum filters; refer to WK72856.

103 7.1.1. Additional analyses can be performed on OGSR components that have been 

104 described elsewhere [WK LC-MS] [5, 6].

105 7.2. Preparation of OGSR samples:

106 7.2.1. Extract swabs, vacuum filters, or adhesive lifts using a suitable organic solvent, 

107 such as methanol, methylene chloride, or acetonitrile [7].

108 7.2.1.1. The volume of solvent used must be sufficient to extract the entire surface or 

109 area of the sample collection item used.

110 7.2.2. Extract the sample by placing the collection item inside a new disposable vial of a 

111 minimum volume required to hold the entire item. Swabs can be folded to fit into 

112 the vial. Add a minimum volume of solvent required to submerge the entire item. 

113 7.2.3. Sonicate the vial with the item submerged in the solvent. Remove the extract and 

114 either filter or centrifuge the item to remove any solid particulates from the 

115 solution.

116 7.2.4. Analyze the filtered or centrifuged extract directly or the extract can be 

117 concentrated, if required for analysis. 

118 7.2.4.1. Concentrate the extract by evaporation down to the required volume using 

119 nitrogen gas or another dry gas.

120 7.2.5. Store extracts at 0°C or colder to maximize preservation, when the sample is not 

121 being analyzed.

122 7.3. GC-MS analysis of OGSR extracts:

123 7.3.1. Common organic components of OGSR can be identified by GC-MS analysis. 
OSAC 2022-S-0002 Standard Practice for the 

Analysis of Organic Gunshot Residue (OGSR) by Gas 

Chromatography-Mass Spectrometry (GC-MS)

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124 7.3.1.1. Nitrocellulose needs to be derivatized prior to analysis. Refer to Test 

125 Method E2999 and included references for additional information [8,9].

126 7.3.2. The extract may be diluted, if required, to improve chromatography or mass 

127 spectral features.

128 7.3.3. Suggested GC-MS parameters are listed in Appendix Table X1.

129 7.3.3.1. Validate this method on the laboratory’s instrument before using the 

130 method in casework (E3255).

131 NOTE: Modify GC conditions to ensure that each peak of the reference test 

132 mixture has baseline resolution.

133 7.3.4. Prior to analyzing samples, the GC-MS should be tuned and calibrated per 

134 validation protocols or the manufacturer recommendations.

135 7.3.5. Table 1 lists the common target compounds and their target ions that can be used 

136 to identify the presence of OGSR.

137 7.3.5.1. Data analysis is limited to the qualitative identification of the target 

138 compounds listed in Table 1. Parameters used for identification can be 

139 observed retention time(s), ions detected, their ion masses, and associated 

140 fragmentation pattern of the molecule. 

141 7.3.5.2. Each specific retention time is measured by analyzing a reference material (see 

142 Sec. 6.3), using the GC-MS system and method under the same instrumental 

143 conditions [8,9,10]. 

144 7.3.5.3. At this time, there are no satisfactory studies completed to determine the 

145 common background presence of OGSR. Therefore, quantitative analysis of 

146 OGSR by GC-MS is not recommended.

147 7.3.5.3.1. It is the responsibility of each individual laboratory to verify any 

148 research study completed in their region concerning the background 

149 presence of OGSR [10,11].

150 7.3.5.4. Interpretation of the presence or absence of target compounds in Table 1 is not 

151 covered in this standard practice (see Sec. 4.4).

152

153 TABLE 1: Typical OGSR related compounds and m/z of target ions in EI MS found by GC154 MS analysis

Target Compound Significance/ 

Application

Target Ions (m/z) Ref.

Akardite II (AK II) Stabilizer 169, 226 [12]

2-amine-4,6-dinitrotoluene (2-ADNT) Degradation products 197, 180 [13]

Dibutyl phthalate (DBP) Plasticizer 149, 223 [13,14]

Diisoamyl phthalate (DIP) Plasticizer 149 [E2999]

2,4- and 2,6-dinitrotoluene (2,4-DNT 

and 2,6-DNT)

Flash suppressor 165, 182 [13]

Dioctyl phthalate (DOP) Plasticizer 149, 279 [E2999]

Diphenylamine (DPA) Stabilizer 169 [4,13,14]
OSAC 2022-S-0002 Standard Practice for the 

Analysis of Organic Gunshot Residue (OGSR) by Gas 

Chromatography-Mass Spectrometry (GC-MS)

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Ethyl centralite (EC) Stabilizer 120, 268 [4,13,14]

Ethyleneglycol dinitrate (EGDN) Explosive 46, 76 [12]

Methyl centralite (MC) Stabilizer 134, 240 [13]

2 and 4-nitrodiphenylamine (2-NDPA, 

4-NDPA)

Degradation products; 

stabilizer

167, 214 [4,13,14]

Nitroglycerin (NG) Explosive 46, 76 [13,14]

4-nitrosodiphenylamine (4-NODPA) Degradation products 167, 198 [14]

N-nitrosodiphenlyamine (N-NODPA) Degradation product Detected as DPA [14]

Nitrotoluenes (NTs) Sensitizer 65, 91, 120 or 137 [13,15]

2,4,6-trinitrotoluene (TNT) Flash 

suppressor/sensitizer

89, 210 [4,13]

155

156 8. Identification of OGSR Compounds

157 8.1. The identification of a compound in an unknown sample should be based upon direct 

158 comparison with a known reference standard of the compound.

159 8.2. The unknown sample should be run on the same instrument using the same method as 

160 the known reference standard.

161 8.3. Identification criteria is provided for the gas chromatography and mass spectrometry.

162 8.3.1. Gas Chromatography

163 8.3.1.1. 8.4.1.1.The retention time of the compound in the unknown sample should 

164 be within ± 0.1 minute of the reference compound.

165 8.3.2. Mass Spectrometry

166 8.3.2.1. The unknown and reference samples should have the same base peak and 

167 the same molecular ion, if present, refer to section 9.2.1. The measured m/z 

168 value of the molecular ion should be within the instrument manufacturer’s 

169 tolerance (mass accuracy) of the theoretical value of the target compound.

170 8.3.2.2. The fragmentation patterns and relative abundances of ions in the mass 

171 spectra of the unknown sample and the reference OGSR sample will 

172 generally agree across the majority of the ions.

173 8.3.2.3. Isotopic ions present in the reference spectrum shall be present in similar 

174 proportions in the unknown sample spectrum; low abundance ions (less than 

175 5% of the total spectral abundance) may be absent without precluding an 

176 identification.

177 8.3.2.4. Background subtraction may be necessary to remove any background 

178 contribution to the sample.

179 8.3.2.5. There shall be no unexplained extraneous ions that have a significant 

180 abundance.

181

182 9. Quality Control

183 9.1. For minimum quality assurance protocols refer to Practice E3255.
OSAC 2022-S-0002 Standard Practice for the 

Analysis of Organic Gunshot Residue (OGSR) by Gas 

Chromatography-Mass Spectrometry (GC-MS)

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184 9.2. Quality assurance protocols specific to this standard practice:

185 9.2.1. Analyze a quality control sample with questioned extracts.

186 9.2.1.1. The quality control sample should be analyzed, at minimum, at the beginning 

187 and the end of the analytical sequence on the instrument.

188 9.2.1.2. Quality control sample contains at least five compounds commonly observed, 

189 as chosen by the individual laboratory, from the chemicals listed in Table 1.

190 NOTE: An example of a quality control sample is as follows: NG, EC, 2-

191 NDPA, DPA, and 2,4-DNT.

192 9.2.1.3. Establish protocols to ensure stability of the quality control sample.

193 9.2.1.4. Store quality control sample under appropriate conditions (see 7.2.5).

194 9.2.1.5. Replace the quality control sample when degradation is observed from the 

195 previous analysis of the sample. Examples of degradation include: the 

196 absence of peaks, the presence of new peaks. The laboratory can also 

197 determine an expiration date for the quality control sample in accordance with 

198 laboratory policy.

199 9.2.2. Analyze blank samples with questioned extracts.

200 9.2.2.1. Prepare a method blank using the same procedure(s), reagents, and conditions 

201 for analysis as the questioned extracts.

202 9.2.2.2. A solvent wash blank shall be analyzed between each sample.

203

204 10. Records

205 10.1. Document the following, electronically or hard-copied, refer to Practice E3255:

206 10.1.1. GC-MS instrument settings and method parameters used for analysis.

207 10.1.2. Calibration and tuning of the instrument used for analysis.

208 10.1.3. Chromatograms of method blank(s), reference material(s), and questioned 

209 samples. Annotate peaks of interest with retention times.

210 10.1.4. Mass spectra of OGSR compounds identified and the associated material(s) used 

211 for comparison.

212 10.1.5. All analytical notes from the analysis including the details of sample preparation 

213 and instrument maintenance. 

214 10.1.6. Maintain reports in accordance with laboratory policy and Practice E3255.

215

216 11. Keywords

217 11.1. OGSR; GC-MS

218

219 12. References

220

221 [1] W. Feeney, C. Vander Pyl, S. Bell, T. Trejos. Trends in composition, collection, persistence, 

222 and analysis of IGSR and OGSR: A review. For Chem 19 (2020), 100250. 

223 [2] S. Benito, Z. Abrego, A. Sanchez, N. Unceta, M.A. Goicolea, R.J. Barrio, Characterization 

224 of organic gunshot residues in lead-free ammunition using a new sample collection device 
OSAC 2022-S-0002 Standard Practice for the 

Analysis of Organic Gunshot Residue (OGSR) by Gas 

Chromatography-Mass Spectrometry (GC-MS)

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225 for liquid chromatography-quadrupole time-of-flight mass spectrometry, Forensic Sci Int 

226 246 (2015), 79-85. 10.1016/j.forsciint.2014.11.002.

227 [3] V. Redoute Minziere, D. Werner, D. Schneider, M. Manganelli, B. Jung, C. Weyermann, 

228 A.L. Gassner, Combined Collection and Analysis of Inorganic and Organic Gunshot 

229 Residues, J Forensic Sci 65 (2020), 1102-1113.

230 [4] W. Feeney, K. Menking-Hoggatt, C. Vander Pyl, C. E., Ott, S. Bell, L. Arroyo, T. Trejos, 

231 Detection of Organic and Inorganic Gunshot Residues from Hands using Complexing 

232 Agents and LC-MS/MS, Anal Methods, 13 (2021), 3024-3039. DOI: 10.1039/d1ay00778e.

233 [5] E. Bernal Morales, A.L. Revilla Vázquez, Simultaneous determination of inorganic and 

234 organic gunshot residues by capillary electrophoresis, J Chromatogr A 1061 (2004), 225-

235 233. 10.1016/j.chroma.2004.10.083.

236 [6] M. Morelato, A. Beavis, A. Ogle, P. Doble, P. Kirkbride, C. Roux, Screening of gunshot 

237 residues using desorption electrospray ionisation–mass spectrometry (DESI–MS), Forensic 

238 Sci Int 217 (2012), 101-106. https://doi.org/10.1016/j.forsciint.2011.10.030.

239 [7] E. Goudsmits, G.P. Sharples, J.W. Birkett, Recent trends in organic gunshot residue 

240 analysis, TrAC Trends in Anal Chem 74 (2015), 46-57. 10.1016/j.trac.2015.05.010.

241 [8] A. Voloshenko Rossin, S. Sladkevich, G. Gasser, A. Melman, O. Lev, Sensitive Analysis of 

242 Nitroguanidine in Aqueous and Soil Matrices by LC-MS, Anal Chem 89 (2017), 9990-9996. 

243 10.1021/acs.analchem.7b02364.

244 [9] A.S. Chajistamatiou, E.B. Bakeas, A rapid method for the identification of nitrocellulose in 

245 high explosives and smokeless powders using GC-EI-MS, Talanta 151 (2016), 192-201. 

246 10.1016/j.talanta.2016.01.038.

247 [10] E. Goudsmits, G.P. Sharples, J.W. Birkett, Preliminary classification of characteristic 

248 organic gunshot residue compounds, Sci Justice 56 (2016), 421-425. 

249 10.1016/j.scijus.2016.06.007.

250 [11] M. Manganelle, C. Weyermann, A.L. Gassner, Surveys of organic gunshot residue 

251 prevalence: Comparison between civilian and police populations, Forensic Sci Int 298 

252 (2019) 48-57.

253 [12] R.V. Taudte, A. Beavis, L. Blanes, N. Cole, P. Doble, C. Roux, Detection of gunshot 

254 residues using mass spectrometry, Biomed Res Int 2014 (2014) 965403.

255 [13] K.H. Chang, C.H. Yew, A.F. Abdullah, Optimization of headspace solid-phase 

256 microextraction technique for extraction of volatile smokeless powder compounds in 

257 forensic applications, J Forensic Sci 59 (2014) 1100–1108.

258 [14] M. Gallidabino, F.S. Romolo, K. Bylenga, C. Weyermann, Development of a novel 

259 headspace sorptive extraction method to study the aging of volatile compounds in spent 

260 handgun cartridges, Anal Chem 86 (2014) 4471–4478.

261 [15] O. Dalby, J.W. Birkett, The evaluation of solid phase micro-extraction fibre types for the 

262 analysis of organic components in unburned propellant powders, J Chromatogr A 1217 

263 (2010) 7183–7188.

264

265
OSAC 2022-S-0002 Standard Practice for the 

Analysis of Organic Gunshot Residue (OGSR) by Gas 

Chromatography-Mass Spectrometry (GC-MS)

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266 APPENDIX

267 (Non-Mandatory Information)

268

269 X1. Instrumental Operation Parameters

270 X1.1 Suggested GC-MS parameters 

271 X1.1.1 An example GC-MS instrumental method, from literature, to analyze OGSR 

272 compounds is provided below as a starting point for the method validation by the laboratory.

273

274 TABLE X1: Suggested GC-MS conditions derived from ASTM E2999.

275

Parameter Condition

GC column: 30 meter, DB-5

Injector Temp: 180° C

Initial Temp (T0): 40-50° C

Hold time (T0): 3 minutes

Ramp 1: 15° C/minute to 150° C (T1)

Hold time (T1): 2 minutes

Ramp 2: 20-40° C/minute to 265° C (T2)

Hold time (T2): 8 minutes

Mode: EI

Scan Mode Full Scan or Selected Ion Monitoring

Split Ratio: Splitless (n/a)

MS range: 40 to 400 m/z

Source Temp: 230° C

Solvent delay: 1-2 minutes

276