Raman spectroscopy used to detect illegal ivory

UK scientists have identified a new way of quickly distinguishing between illegal elephant tusk ivory and legal mammoth tusk ivory, which could help customs teams to crack down on the illegal ivory trade worldwide.

While trading and procuring elephant ivory is illegal, it is not illegal to sell ivory from extinct species, such as preserved mammoth ivory. This poses a problem for customs teams as ivory from these two different types of tusk are broadly similar, making them difficult to distinguish from one another — especially once specimens have become worked or carved.

Scientists from the University of Bristol’s School of Anatomy and Lancaster Medical School sought to establish whether Raman spectroscopy, a laser-based method which is already used in the study of bone and mineral chemistry, could be modified to accurately detect differences in the chemistry of mammoth and elephant ivory. The non-destructive technology, which involves shining a high-energy light at an ivory specimen, can detect small biochemical differences in the tusks from elephants and mammoths.

Researchers scanned samples of mammoth and elephant tusks from London’s Natural History Museum using Raman spectroscopy. Results from the experiment, published in the journal PLOS ONE, found the technology provided accurate, quick and non-destructive species identification.

As noted by study co-author Professor Adrian Lister, from the Natural History Museum, a quick and reliable method for distinguishing between elephant and mammoth ivory “has long been a goal, as other methods (such as radiocarbon dating and DNA analysis) are time-consuming and expensive. The demonstration that the two can be separated by Raman spectroscopy is therefore a significant step forward; also, this method (unlike the others) does not require any sampling, leaving the ivory object intact.”

“Raman spectroscopy can provide results quickly (a single scan takes only a few minutes) and is easier to use than current methods, making it easier to determine between illegal elephant ivory and legal mammoth tusk ivory,” added Dr Rebecca Shepherd, formerly of Lancaster Medical School and now at the University of Bristol’s School of Anatomy.

“Increased surveillance and monitoring of samples passing through customs worldwide using Raman spectroscopy could act as a deterrent to those poaching endangered and critically endangered species of elephant.”

Image caption: A selection of elephant and mammoth tusk samples. Image credit: Ben Booth.