. 

TWGFEX Laboratory Explosion Group 

Standards & Protocols Committee 

Recommended Guidelines for Forensic Identification of Intact Explosives 

1.1 Introduction: 

The purpose of this document is to set forth guidelines for the forensic identification of intact 

(unconsumed) explosives. It is recognized that the correct characterization and/or identification 

of an explosive depends on the use of scientifically acceptable analytical methods and the 

expertise of the analyst. Unique requirements in different jurisdictions may dictate practices 

followed by a particular laboratory. This document does not discourage the use of any particular 

method within an analytical scheme and recommends the use of multiple techniques based on 

different principles and methodologies. Analytical chemistry is an advancing science and there 

are other analytical techniques which are not listed in the document but which may be employed 

in the identification of explosives. These may be new techniques or established techniques (i.e. 

NMR), which are not routinely used in forensic laboratories. 

1.2 Categorizing Analytical Techniques: 

For purposes of this document, techniques for the analysis of explosive samples may be broken 

down into four categories: (1) those that provide significant structural and/or elemental 

information, (2) those that provide limited structural or elemental information, (3) those that 

provide a high degree of selectivity, and (4) those that are useful but do not fall in either of the 

other categories. Table 1 lists examples of such techniques based on the 1999 TWGFEX survey 

of explosion debris analysts in the United States. 

Table 1: Categories of Analytical Techniques 

Categories 1 and 2 Category 3 Category 4 

Infrared Spectroscopy (IR) Gas Chromatography (GC) Burn Test 

Gas Chromatography/Mass 

Spectrometry (GC/MS) 

Gas Chromatography 

Thermal Energy Analyzer 

(GC-TEA) 

Flame Test 

Energy Dispersive X-Ray 

Analyzer (EDX) 

Liquid Chromatography 

(LC) Spot Test 

Raman Spectroscopy 

Liquid Chromatography 

Thermal Energy Analyzer 

(LC-TEA) 

Melting Point 

X-Ray Diffraction (XRD) Ion Chromatography (IC) 

Liquid Chromatography/ 

Mass Spectrometry 

(LC/MS) 

Capillary Electrophoresis 

(CE) 

Guide for identification of intact explosives 

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Categories 1 and 2 Category 3 Category 4 

Thin Layer 

Chromatography (TLC) 

Ion Mobility Spectrometry 

(IMS) 

Polarizing Light 

Microscopy (PLM) 

Stereo Light Microscopy 

(SLM) 

1.3 Recommended Practices: 

1.3.1 Good laboratory practices suggest that multiple techniques be employed in forensic 

explosive identification and that supporting analytical data be available for review. 

Examples of such data include printed chromatograms, photographs/photocopies of 

results, or detailed descriptions of morphological characteristics. 

1.3.2 Examination of suspected explosives should start with macroscopical and microscopical 

observations and, when appropriate, a burn test. The usefulness of these initial tests 

assumes the examiner has a working knowledge of explosives. While the visual 

examination and burn test may be suggestive of an explosive, it is necessary to use 

additional analytical techniques to identify the explosive compound itself or its key 

constituents. The key constituents are highlighted in red (or shaded in B&W copies) for 

each applicable type of explosive on the chart in Appendix A. 

1.3.3 In addition to the visual examination and burn test of the intact sample, individual 

component(s) (shaded or in red in Appendix A) of the explosive must be identified as 

follows: 

1.3.3.1. A technique identified with a numeral 1 is sufficient for identification. 

1.3.3.2. A technique identified with a numeral 2 requires one more supporting technique 

for identification. 

1.3.3.3. A technique identified with a numeral 3 requires two more supporting techniques 

for identification. 

1.3.3.4. A technique identified with a numeral 4 requires three more supporting 

techniques for identification. 

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1.3.4 Clarifications to 1.3.3 

1.3.4.1 When identifying ions, two techniques per ion are required. 

1.3.4.2 Some category 3 techniques lend themselves to being counted twice: 

• Chromatographic techniques may be counted as two distinct Category 3 

methodologies when different stationary and/or mobile phases are 

employed. 

• PLM may be counted as two distinct Category 3 methodologies when 2 

different identification tests are done, such as examination of the 

physical/optical properties plus a microcrystalline test 

1.3.5 For an analytical technique to be considered of value, the test must be considered 

‘positive’. While ‘negative’ tests provide useful information for ruling out the presence 

of a particular family of explosives, these results have limited value toward establishing 

the identification of an explosive substance. 

1.3.6 Forensic laboratories are encouraged to establish reference collections. The 

collections should contain explosives that the laboratory is likely to encounter. Digital 

images or photographs of a few examples of each explosive would be useful to assist 

examiners. Examples include: 

1. Black Powder 

2. Pyrodex/ Triple 7

3. Black Canyon/Clean Shot

4. Flash Powder/Pyrotechnic 

5. Smokeless Powder (single-base & double-base) 

6. Dynamite 

7. Watergel/Slurry 

8. Emulsion 

9. ANFO 

10. Binaries (e.g. Kinepak) 

11. Plastic Bonded Explosives 

12. Single Component Explosive (e.g. TNT, PETN, RDX, HMX, EGDN, Tetryl, 

Azides) 

1.4 Appendix A is a chart showing analytical techniques that may be used for identifying 

common, intact commercial explosives. This chart also shows the recommended 

constituents (in RED or shaded) that must be individually identified for multiple 

component explosives. The identification of these components forms the basis for 

identification of the explosive material. 

Guide for identification of intact explosives 

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1.5 Safety: 

The laboratory is strongly encouraged to establish safety protocols for the safe execution 

of these procedures. 

1.6 Summary: 

It is understood that the forensic identification of an explosive may be accomplished by a 

variety of analytical techniques. These guidelines recommend that at least one Category 

1 technique be utilized in performing forensic explosive identifications. The use of 

multiple techniques and methodologies that provide structural and/or elemental 

information about an explosive is strongly recommended. It should be recognized that 

these guidelines are minimum standards for the identification of explosives. Within these 

guidelines, it is at the discretion of the individual analyst to determine which combination 

of analytical techniques satisfies the requirements for the identification of an explosive. 

These guidelines were formulated with the express intent of application to commercial 

explosives. Improvised explosives should be identified using similar principles. 

Guide for identification of intact explosives 

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APPENDIX A 

Minimum Analysis Requirements for Identification of Intact Explosives 

MATERIAL GC/MS LC/MS IR EDX RAMAN XRD GC/TEA GC LC/TEA LC IC CE TLC IMS PLM SLM BURN FLAME SPOTS MELTING 

POINT 

Black Powder 3 4 

Potassium Nitrate 1 3 2 1 3 3 3 4 4 

Sulfur 1 1 1 3 3 4 

Carbon 2 3 3 4 

Pyrodex 3 4 

Potassium Nitrate 1 3 2 1 3 3 3 4 4 

Potassium Perchlorate 1 3 2 1 3 3 3 4 4 

Sodium Benzoate 2 1 3 2 1 3 3 3 3 

Dicyanodiamide 1 1 3 3 3 3 

Sulfur 1 1 1 3 3 4 

Carbon 2 3 3 4 

Triple 7 3 4 

Potassium Nitrate 1 3 2 1 3 3 3 4 4 

Potassium Perchlorate 1 3 2 1 3 3 3 4 4 

Sodium Benzoate 2 1 3 2 1 3 3 3 3 

Dicyanodiamide 1 1 3 3 3 3 

Absence of Sulfur 

Carbon 3 3 4 

Black Canyon/Cleanshot 3 4 

Ascorbic Acid 1 1 2 1 3 3 3 

Potassium Nitrate 1 3 2 1 3 3 3 4 4 

Flash Powder 3 4 

Metal Fuel 1 1 3 3 4 

Oxidizer 1 3 2 1 3 3 3 4 4 

Fillers/Binders 2 2 3 3 

Smokeless Powder 3 4 

Nitrocellulose (SB) 1 2 3 4 

Nitroglycerin (DB) 1 1 2 3 3 3 3 3 4 

Dynamite 3 

Nitrate Esters (ID all Present) 

Nitroglycerin 1 2 2 3 3 3 3 3 4 

EGDN 1 2 2 3 3 3 3 3 4 

Metriol trinitrate (MTN) 1 2 2 3 3 3 3 4 

DEGDN 1 2 2 3 3 3 3 4 

Ammonium/Sodium Nitrate 1 3 2 1 3 3 3 4 

Filler Material 2 3 2 2 3 3 

Other inorganic salts 2 3 2 1 3 3 3 4 

TNT 1 1 1 2 1 3 3 3 3 3 4 4 

PETN 1 1 1 2 1 3 3 3 3 3 3 4 4 

RDX 1 1 1 2 1 3 3 3 3 3 3 4 

HMX 1 1 1 2 1 3 3 3 3 3 4 

EGDN 1 2 2 3 3 3 3 3 4 

TATP 1 1 2 1 3 4 4 4 

HMTD 1 1 2 1 3 4 4 4 

TETRYL 2 1 1 2 1 3 3 3 3 3 3 4 4 

WATER GELS/SLURRIES 3 

Inorganic Nitrate 1 3 2 1 3 3 3 3 4 4 

Gelling Agent(polysaccharides) 1 2 

Sensitizers (ID all Present) 

Microballoons 2 1 1 3 

Aluminum 1 1 3 3 4 

MMAN/EDDN 1 2 3 3 3 3 3 

EMULSIONS 3 

Inorganic Nitrate 1 3 2 1 3 3 3 3 4 4 

Oil/Wax 1 1 1 

Emulsifiers 1 2 2 

Sensitizers (ID all Present) 

Microballoons 2 1 1 3 

Aluminum 1 1 3 3 4 

ANFO 3 

Ammonium nitrate 1 3 2 1 3 3 3 3 4 4 

Fuel Oil 1 2 1 

BINARIES(Kinepac,Thermex,etc) 3 

Ammonium nitrate 1 3 2 1 3 3 3 3 4 4 

Nitromethane 1 1 2 3 3 

PLASTIC BONDED EXPLOSIVES 3 

Explosive (RDX, HMX, PETN) 1 1 1 2 1 3 3 3 3 3 3 4 

Dye 1 1 2 3 3 3 

Binder 1 2 

Plasticizer 1 1 2 3 3 

Oil 1 1 

DMNB (taggant) 1 3 3 3 3 

PRIMARY EXPLOSIVES 3 4 

Azides 1 3 2 1 3 3 3 4 

Styphnates 1 3 2 1 3 3 4 

Diazodinitrophenol (DDNP) 1 1 2 1 3 3 3 4 

Fulminates 1 3 2 1 3 4 

Guide for identification of intact explosives 

Appendix A