Detecting illegal drugs using light
One way to smuggle illicit cargoes - whether they're explosives or other substances like drugs - is in suitcases and hand baggage. But because scanning and opening these to test them is relatively easy, criminals have changed tactics. A recent trend is to dissolve drugs in alcoholic drinks, like rum, which is a headache for customs officers because it means they need to open - and potentially destroy - bottles in a shipment to be able to test them.
Now scientists are fighting back, using a light-scattering technique called Raman Spectroscopy that can see what's inside a liquid, inside a bottle, without having to open it. Amelia Perry went to meet the researchers behind the breakthrough, Bradford University's Tasnim Munshi and Richard Telford...
Tasnim - Raman spectroscopy is a very useful technique. It's fast, easy to use, and with recent new developments in software, it's got to the stage where it doesn't need a trained scientist to use the instrument especially in security settings.
Amelia - So, how does Raman spectroscopy work, Richard?
Richard - Raman spectroscopy works by shining a laser directly onto the sample. The light interacts with the sample and gives us what we call a spectrum which is essentially like a chemical fingerprint of that sample. These can then be matched against databases that people have built up. It then tells exactly what that sample is and this has obviously got great uses in finding drug samples in a forensic sense. With Raman spectroscopy, we can choose to focus the laser light directly through the side of the container that we're interested in. For example, we can focus that laser straight through the side of a bottle or through a plastic bag and we can actually collect the spectrum from the material that's contained within that.
Amelia - We then moved into the laboratory in order to see exactly how this technique works. Upon entry into the lab, I was confronted by a rather large machine which looked a lot like a microscope attached to a giant metal box around 2 metres long in total. When turned on, the metal box generates a very strong laser beam that is focused through the microscope lens onto the drug sample. The readout that is created called a Raman spectrum appears on the computer screen, ready for analysis.
Richard - So, I'm just going to bring into focus a very small crystal of the cocaine sample that I've put on the microscope slide which is then going to allow us to expose that to the laser energy and acquire a Raman spectrum. The series of peaks that we can now see on screen give us a chemical signature or fingerprint if you like of the cocaine sample that we've just analysed. By matching that to databases that we've previously acquired, we can get our result.
Amelia - We then moved back into the office to look at a handheld version of the large piece of instrumentation we had tested out in the laboratory. It is being developed by Thermo Scientific and has been named TruNarc.
Tasnim - It works in exactly the same way as a larger lab-based instrument. It has an in-built database of a large number of drugs ranging all the way from things like cocaine, ketamine, LSD, ecstasy.
Amelia - This device is small enough to fit into your hands and has been right now is actually shining a laser coming out of the side into a sample pot. So, she simply presses a button and on the screen, it says, 'scanning in progress'. So, what's happening here, Tasnim?
Tasnim - The TruNarc system works in exactly the same as the lab-based instrument. It's scanning the sample and instead of giving us a very complicated spectrum, it matches it against our database and it's clearly come up. It's shown that it's a ketamine sample and we've analysed this sample through a nice clear glass bottle. So obviously, we don't know we'd get drugs in nice clear bottles. And so, we've got another sample here. we've got cocaine dissolved in rum in a brown glass bottle. We're going to just try this and it's clearly shown up it's cocaine hydrochloride.
Amelia - So, what are the benefits of this handheld device, Tasnim?
Tasnim - As we've just seen, it's a really quick system to use. It takes about 30 seconds to collect a spectrum. It's portable so it's battery-powered, so we can use it anywhere. It does not need a trained scientist to use it and it saves us a lot of work in terms of sending off samples to labs. It's very, very specific, so it'll tell us whether it's a sugar or whether it's a drug of abuse.
Amelia - Where can this device be used?
Richard - So, it can be used in airports by customs department to check for smuggling of drugs of abuse, in large shipments of alcohols for example. It can be used by police forces and is currently been used by a number of national and international police departments where they can get a very, very quick analysis of what types of drugs they may have confiscated from people they've arrested.
Amelia - So, it seems like a really effective system, but are there any limitations?
Tasnim - There are some limitations. For example, if it's a very, very complex mixture, would the instrument be able to pick it up? We think so. We've tried it with a number of different mixtures and it does pick up mixtures. With regards to different coloured liquids, we can work through coloured glass. We've tried green, we've tried brown glass, and we've also tried in rum samples, so brown liquids. But there will be some liquids where colour can be an issue. With the big lab-based instruments, we've tried different wavelengths of light and that seems to work quite effectively and that can be incorporated into new portable instruments. Again, the instrument is only as good as the database. New drugs are continuingly coming onto the market and we can't really keep up with new legal highs. We are working with the University of Lincoln's forensics department as well the manufacturers of the instruments to add to the database continuously.
Amelia - What other applications are there for Raman spectroscopy as a technique?
Richard - So, Raman spectroscopy is used in a huge variety of application areas, in a similar way to the drugs analysis in airports that we've already talked about. The technique has been successfully used to detect explosive samples or even find ivory samples being smuggled into the country. I use the technique primarily for analysis of pharmaceutical materials where for example, we can use it to detect different solid forms of prescribed pharmaceuticals. It's also applied for example in food analysis in the food industry.
Tasnim - And also, forgery of art, looking at age and composition of paint, so you can age paintings. And finally, it's been sent to Mars on the next ExoMars Mission to check signatures of life, so a vast variety of applications.