CAOG - PhD Students

Miss Tamara Pilgrim

The application of trace element and stable isotope signatures to the provenance establishment of plant derived products of forensic significance

The ability to provenance plant materials is important to the forensic investigator and therefore much time has been spent in research around methods that would achieve this task. Plant materials of interest may involve food products, drugs and crime scene debris. As a plant grows it is affected by its surrounding environment. The soil in which a plant is grown, the water it drinks and the air it breathes affects the chemical make-up of the plant. If this chemical signature is maintained during harvest and processing, it may be possible to link the plant back to its original growing region.

The initial study has been limited to three types of plant products; olive oil, tea leaves and cannabis. This is to cover a range of the types of plant derived products and different degrees of post harvest processing. The aim is to see if the fingerprint obtained from the final product can be used to establish the growing region of that product. Analysis of the samples has involved a combination of two methods, stable isotope ratio analysis and trace element analysis. The stable isotope composition of a substance is determined by its biological origin and environmental history.  Analysis of the hydrogen, carbon and nitrogen isotope ratios using isotope ratio mass spectrometry (irMS) allows an initial separation of samples. Inductively coupled plasma mass spectrometry (ICP-MS) is then used to establish an elemental profile for the samples. The samples are introduced both in solution form (after acid dissolution) and also solid form (laser ablation ICPMS). This provides information on the geological origin of the samples. By combining the data from the two methods, environmental, geological and treatment differences are examined allowing the growing region to be better defined.

The establishment of a robust method for the analysis of olive oil, tea, and cannabis using isotope ratio and trace element analysis to determine regions of origin will provide investigators with a significant tool in the investigation of fraud and drug investigations. This will also give a significant footing on which to develop techniques for the provenancing of other plant related materials. This could then be applied to an unlimited number of circumstances where plant material may be encountered in a forensic setting, for example fraud, drug seizures, tracing native flora and crime scene debris.

Supervisors

Professor John Watling, Prof Kliti Grice, Colin Priddis, Dr Paul Greenwood

Funding

APA