Cocaine sensor: A potential on-the-go screening aid

One of the most lucrative business in the new world turns around cocaine. Because it is an expensive recreational drug with high demand and with a non-descript appearance, dealers find a breach to fool the users – and maximize their profits – by mixing the psychotropic with similar-looking white powders. Baking soda, talcum powder, boric acid, local anesthetics and laundry detergents are only some of the backstage actors in this somber business. You can imagine that these additives are health-threatening, undoubtedly, in addition to the drug itself. Addicted users suffer the lasting consequences due to frequent intake. To aid in fighting illicit drug abuse, electrochemistry comes with a helping hand -- and I am glad I got to shake it.

My research topic deals with the development of a portable electrochemistry-based sensor to detect illicit drugs. The current model drug used is cocaine, and we have had euphorically good results with the first prototypes. These sensors are actually intended to be way more reliable in drug detection than their primitive counterparts -- aka colorimetric tests. They are also less expensive and cumbersome than the field superstars – namely, spectrometry machines – which are irreplaceable due to the level and precision of detection they are capable of. However, they require trained personnel, dedicated space, time to analyze the samples and frequent maintenance. My solution is meant to fill in the ‘white gap’ and hit the road.

This is all very exciting news. But how does the sensor work? Well, my system is based on a non-conventional electrochemical approach since I use two immiscible liquids – like water and oil – both containing ions to do the trick instead of solid electrodes as more commonly imagined. You could think that due to affinity, the ions in the oil phase would not like to be in the water phase. This is exactly right. Actually, different ions have a different affinity for different solvents. Small inorganic ions (e.g.sodium, potassium, nitrite, sulphate) prefer to be in water. Large organic ions (e.g.charged soap molecules) prefer the oil phase. However, if you unsetttle the system (providing enough energy, for example) the ions can cross the water-oil interphase and – abracadabra! – the cocaine molecules present in the oil-like phase make their way to detection. At this stage, all you need is to collect the information about cocaine dissatisfaction of being away from its lovingly comfortable phase, analyse it and translate it into information that chemists can read. This is easily said, just a “little” more complex in reality.

What is truly amazing is that we got promising results when testing the prototype with street cocaine, i.e., the one containing often unknown mixtures of other chemicals. These “polluting” ions/molecules in the system could normally mess up the detection, but it worked.

With the goggles of an electrochemist, however, it can be discouraging to work in this space as a result of stringent regulations existing around illicit drugs – at least when it comes to purchasing them for research purposes. This may be one of the reasons why there is not enough scientific attention given to the topic. I trust that a different reality exists in the dark web… I will continue the scientific fight, though!

I am Łukasz Półtorak, and I am an Assistant Professor affiliated with Prof. Sławomira Skrzypekat the University of Lodz, Department of Chemistry in Poland as well as with Prof. Ernst J.R. Sudhölter at the Delft University of Technology, Department of Chemical Engineering in The Netherlands. Co-operation with Marcel de Puit (Dutch Forensic Institute) made this work possible. The research work is partially funded by the National Science Centre (Poland). Grant number 2018/31/D/ST4/03259.

For the science freaks out there: Poltorak et al., Electrified Soft Interface as a Selective Sensor for Cocaine Detection in Street Samples, Anal. Chem., 90, 12, 7428-33, 2018.


Digital art

Text by Fernanda Haffner

Illustration by Laurene Gattuso