Stable isotope mass spectrometry is linking batches of materials used in crimes.

It is now possible to trace samples of packaging material used in drug trafficking and other serious crimes by using their unique isotopic signature. Mimicking DNA profiling techniques for identifying individuals, James Carter and his team at Mass Spec Analytical in Bristol, UK, have developed a method to link samples found at different times and locations using the sample's isotopic signature.

All natural and manufactured material has an isotopic signature. This signature is related to both the material's chemical composition and any physical or chemical processes it has been subjected to. Any two samples made from identical ingredients in exactly the same manner will share the same signature. Carter's team have utilised this fact to use stable isotope ratio mass spectrometry of carbon, hydrogen and oxygen to distinguish between batches of adhesive tape. The tape could have been used to seal batches of illegal drugs, to contain a terrorist device or in the disposal of a body after a murder.

The current work builds on the group's previous research into using stable isotopes to track the origins and distribution of controlled drugs. According to Carter the next step will be to develop comprehensive databases to demonstrate the extent of isotopic variation in forensically important materials. It is important to know the probability of two materials having the same isotopic signature simply by chance. Linked to this he feels that the final test will be when the technique is fully challenged in a court of law.

Suzanne Abbott