When you're trying to establish who was present when a crime was committed, every little clue helps. That's where a newly repurposed forensic technique comes in, as it can determine if oral fluid comes from a smoker or non-smoker.
The technique is in fact an existing process known as Raman spectroscopy, in which monochromatic light (usually from a laser) is shone onto a sample. The molecules in that substance vibrate in response, scattering the light in a unique manner. Therefore, by analyzing that scattered light, it's possible to ascertain which chemicals are present in the sample.
Led by Prof. Igor Lednev, researchers from the University at Albany found that cotinine – which is the main metabolite produced by the body in response to nicotine intake – has a distinctive and recognizable spectroscopic signature within oral fluid. Consisting of more than just saliva, oral fluid also contains "oral mucosal transudate," which is in turn derived from blood serum.
In lab tests, the scientists used Raman spectroscopy to analyze samples from 32 volunteers of differing ages, races and sexes. Half of those people were self-described regular smokers, while the other half claimed they had never smoked. Based on the cotinine readings, the team was accurately able to determine whether or not each sample came from a smoker.
More research still needs to be conducted, on factors such as the effect that food and drink have on oral fluid content. Ultimately, though, it is hoped that the technology could assist in the solving of crimes.
"Our goal is to help crime science investigators (CSIs) build a phenotype profile for suspects in the early stages of an investigation," says Lednev. "A CSI would, of course, prefer to build a DNA profile. But, that is often not an option. We offer a viable alternative."
The research is described in a paper that was recently published in the Journal of Biophotonics.
Source: University at Albany
