# δ13C and δ15N Values of Residues Provide Insights Into Identification of the Explosive Source

## TL;DR

This study shows how measuring carbon and nitrogen isotopes in explosive residues can help identify the type of explosive used after a blast.

## Contribution

The novel contribution is demonstrating that δ13C and δ15N values in postblast residues can be linked to the source explosive materials.

## Key findings

- δ13C and δ15N values of TNT residues were similar to the source explosive, indicating minimal isotope enrichment.
- RDX residues showed δ15N values similar to the source, but δ13C values were enriched by nearly 2‰ after detonation.
- Similar isotope patterns were observed in HMX, RDX, and NT residues collected from field detonations.

## Abstract

Postblast analyses of military and terrorist events will benefit from the capacity to learn more about the explosive materials used in an event. Here stable isotope ratio analyses (δ13C, δ15N) can provide additional information to complement identification of the explosive components.

Controlled detonations using different types of military‐grade explosives were conducted in 55‐gal barrels. Additionally, soil analyses were conducted following Mark‐84 field detonations. Swab materials and soils were purified to analyze explosive compounds using established HPLC and IRMS techniques.

Explosive materials were recovered in the residues of TNT (aromatic‐based explosive) and RDX (nonaromatic explosive) detonations in barrel experiments. Explosive residues were not recovered from PETN (nonaromatic explosive). Postblast δ13C and δ15N values of TNT residues were similar to δ values in the source explosive, suggesting minimal enrichment in δ residues. While δ15N values of RDX in postblast residues were also similar to preblast source values, postblast RDX δ13C values were enriched by almost 2‰ relative to the preblast explosive. Similar patterns were observed in HMX, RDX, and NT recovered from soils following Mark‐84 detonations.

δ13C and δ15N values can be effectively measured on explosive compounds recovered in residues following detonations. Residue δ13C and δ15N values can be linked to δ values of undetonated explosive compounds. Additional field studies should be conducted to verify these results.