Rapidly identify “on-scene” drugs with powderpuck
UvA PhD-student and chemist at the police laboratory Ruben Kranenburg has developed a detector to analyse drugs on the spot. The so-called powderpuck can identify 80 percent of the most common drugs within seconds.
On a Wednesday afternoon in late November, it is quiet in the forensics lab of the police station in Sloterdijk. On the windowsill are trays of plastic bags of drugs, stapled to forms, waiting to be analysed. “If there is no immediate urgency, things sometimes pile up a bit,” says Ruben Kranenburg, analytical chemist at the Forensic Investigation Service of the Amsterdam Police Department and associate professor at the UvA. “We have just had the Amsterdam Dance Event, so we still have work from October and November.”
What drugs does he find most often in the police lab? “Cocaine, ecstasy (MDMA)... methamphetamine is not popular in the Netherlands, but speed (amphetamine) is. Heroin we also see, but is not something the nightlife crowd uses. And then there is GHB, one of the few liquid drugs. Very addicting; it really kills people.”
Bert & Ernie
Kranenburg, who has now been working at the police lab for more than thirteen years, saw the drug world change during that time. He saw the use of cocaine increase in Amsterdam. And saw how ecstasy pills, with the advent of tablet machines via AliExpress, changed from dull, round pills to brightly coloured, collectible items with Rolex crowns, Mercedes logos and Bert & Ernie.
He also saw the emergence of new, psychoactive substances: designer drugs. Designer drugs closely resemble existing drugs but are not yet included in the Opium Act's list of prohibited substances because they are chemically slightly different.
At the same time, with the broadening of new substances on the drug market, he saw police running into limitations in being able to test all new drugs accurately and quickly. “For a conviction, drugs must be identified at the molecular level. They then have to go to the lab first. That can take several days, while in the meantime the suspect is detained, awaiting a speedy court hearing, which requires the lab report. Sometimes police investigations cannot proceed immediately because they have to wait for the laboratory results.”
Handheld equipment that can identify drugs on the spot could be a godsend for police. Commercial equipment to test explosives and later “on-scene” drugs came on the market after 9/11.
But Kranenburg does question how thoroughly tested that equipment is. “I think that for the drug market, it is not possible to leave that entirely to free market forces. After all, a commercial party cannot dispose of a large quantity of practical samples of drugs. Then you get a product that is just not quite fit for purpose. Suitable for initial indication and suspicion, but not completely reliable for conviction. I think the police need to work with the academy and commercial parties to get optimal detectors.”
From his position at the police lab, Kranenburg did have the field samples at his disposal, and in consultation with UvA professor of forensic analytical chemistry Arian van Asten (HIMS), he decided to investigate new techniques for "on-scene" drug analysis himself to pursue a doctorate on them.
Ice hockey puck
During his PhD, Kranenburg worked with the UvA, the police lab and the Amsterdam software company TIPb on the powderpuck, a device that looks like an ice hockey puck and can identify 80 percent of the most common drugs within seconds. Kranenburg places a plastic bag of powder on top of the powderpuck, which is connected to a laptop via USB. A spectrum and the word “cocaine” appear on the laptop screen.
“With near-infrared (NIR) light, the puck measures the contents of the bag," Kranenburg says. "And a spectrum then appears on the computer, unique for each organic substance. The puck has its own library of prohibited substances that we have extensively validated. When a new substance appears on the market, we simply add it to the library.”
(Continue reading below the image.)
The powderpuck not only identifies drugs, but also substances similar to them. Kranenburg says: “In practice, we often come across substances such as paracetamol, caffeine, lidocaine and sugar. As a loose substance - so not punishable - or as a cut in cocaine.”
Mixtures that are encountered a lot in drug practice are more difficult to measure. But the data model developed by TIPb proved unerringly capable of identifying these mixtures. “Only if the cocaine content is lower than 20 percent, the powderpuck sometimes no longer measures it correctly. Then the substance is still sent to the lab. But cocaine that has been cut this far, rarely occurs.”
There are already handheld detectors on the market such as a Raman spectrometer costing at least €20,000. “Not the kind of expensive equipment you want to put in every police car.” The powderpuck could be produced for a considerably lower amount.
For now, the powderpuck is not yet being used to replace the lab equipment at the police lab. “I myself am still somewhat cautious about that. There is no law that prescribes how much evidence you must have before you can use it in criminal cases, but we are used to using very elaborate equipment: an advanced device (a GC-MS) worth a ton to measure pure cocaine is quite a bit of overkill. But at the same time, we are used to that. And you also don’t want to end up in technical discussions in court with other scientists who don’t know the equipment yet. That is why we are now opening ourselves up to substantive discussions with, for example, the Dutch Forensic Science Institute.”
Preliminary PhD-defence date: May 12, 2023 at 2:00 p.m. Location: Auditorium (Old Lutheran Church). Admission: free.
