Officers who encounter potential illegal substances in the field need not be chemists to presumptively identify them – there are numerous tools that can do that for them. But when you’re choosing among those tools and methods, with concerns like personal safety and eventual conviction, it can be good to know a bit about what they do and how.
Most common field drug identification tests are based on colorimetric chemistry. Simply put, when you suspect a substance might be something illegal, this process presumptively confirms or rules that out through the color produced when a sample is exposed to a standard reagent. There are several ways to achieve that exposure – the main difference among such tests is the “how,” as they use the same reagents – but in general the process is fast, portable and inexpensive. Though positive results still require laboratory confirmation, the tests are common in law enforcement.
The performance requirements of colorimetric field drug test kits are spelled out by the National Institute of Justice in its Standard 0604.01 on Color Test Reagents/Kits for Preliminary Identification of Drugs of Abuse. This document specifies the information such tests should include, how things should be labeled, safety precautions, use conditions and procedures, and more. It’s intended as a guide to help law enforcement organizations ensure their tests meet key quality requirements.
While many do, the simple wipes provided by Trace Eye-D may be the safest and easiest to use. They are pretreated with the reagents to detect fentanyl and other opioids, methamphetamine and cocaine (others work for explosives) and work with that one simple motion – just open, wipe and wait for the result. No mixing or manipulating samples is required, and results appear in seconds.
FENTANYL WIPES USE A NEW REAGENT
That’s pretty simple, but it’s nonetheless a new approach for most LEOs.
“I don’t think anybody thought of it before because we had the ampoules,” said Susan Hallowell, Ph.D., a veteran analytical chemist with extensive government experience who advises Trace Eye-D. “And the other thing is, these kits were developed by scientists. Scientists are very happy to have little bottles and drops and stuff. Sometimes they tend to say, ‘This is what you need because I made it’ rather than finding out what users want.” Such an approach may generate problems in the less-controlled environments of police work.
Besides improving methods of delivery, Trace Eye-D is also working to advance the actual testing agents. Its fentanyl/opioid wipes are the first to use a new reagent, a fluorescent dye called eosin y that’s often used as a histologic stain.
Eosin y was first evaluated as a colorimetric reagent for opioids, including fentanyl, in 2017 and determined to have great potential for field use. The dye is inactive until used, its sample volume requirements are small, and it’s safe and nontoxic. That early data showed high specificity for fentanyl and other opioids even in complex mixtures of other chemicals presented by drug dealers. Eosin can detect fentanyl amounts down to 1% even in samples with common cutting agents. It’s also effective against 4-ANPP, a known precursor to fentanyl, and fentanyl analogs.
Trace Eye-D’s fentanyl wipes contain less than a 1% solution of eosin y on a wet wipe that’s simply touched to the sample. A positive result turns orange/pink immediately. “If you have a white powder or a liquid solution,” Hallowell said, “that’s a perfect application.”
It’s also effective against residues of drugs – and law enforcement organizations obtaining field drug test products should understand the differences between trace and bulk detection.
Bulk detection requires hundreds of grams of substance and, generally, x-ray or millimeter wave technology to identify it. Trace detection needs about 100 nanograms – that’s 0.0000001 grams. For context, take a packet of sugar, dissolve it in an Olympic-size pool and take an 8-ounce glass out – that’s about how much sugar you’ll have. Police conducting field drug identification tests usually have more material than that, with amounts that are at least visible.
There are other methods of trace detection besides colorimetric, including ion mobility detectors, but the one most viable for cops in the field is dogs – and they come with care costs and travel delays when needed at scenes. Additionally, the canines are trained to detect a lot of different drugs and cannot communicate which ones they have identified. Thus, when marijuana became legal in some states, a new generation of K-9s had to be trained to not cue on cannabis. This makes a colorimetric wipe a valuable complementary detection method to canines, as it will identify the class of drugs that canine identified.
Chemical identification detection is a category that includes the Raman and FTIR (Fourier-transform infrared spectroscopy) technologies used by many law enforcement agencies. It isn’t exactly trace detection, but it can produce a chemical identity. It requires a bit more material to test than trace detection, roughly 1 microgram to half a gram and above.
“It’s a useful technology, but you need enough [test material] to be able to see it,” said Hallowell. “And because it’s a chemical fingerprint, you really need the matching library to compare your result against. But the thing about Raman is that if I’m a clever bad guy, I can make a chemical analog that’s not in your library, so your Raman may not hit on it as a positive. So there are ways to mess with it, whereas you can’t mess with colorimetric detection with clever analogs.”
That sureness of colorimetric identification produced by Trace Eye-D wipes has now been recognized in Florida’s sixth judicial district, which has determined the evidence represented by the company’s test results meets its relevant evidentiary standards and can be used in court. That initial approval is expected to contribute to additional approvals elsewhere.
CONTEXT MATTERS
While colorimetric field tests are highly dependable, they are not infallible – hence the need for laboratory confirmations. Occasional news stories chronicle false positives that have led to wrongful incarcerations.
There’s no magic bullet against that problem, but simpler processes and easy-to-interpret results can go a long way toward averting incorrect results. Beyond that, for officers facing such scenarios, context matters.
“The best way to minimize false positives is to understand what you have: It’s a presumptive test,” said Hallowell. “If you get a positive identification, you need to back it up with secondary chemical confirmatory analysis. The reagent used to identify cocaine also reacts with benzocaine, with lidocaine, with a bunch of “-caines” because it’s chemically similar. So, if you understand there is this potential of cross-reactivity, that helps you.”
When ion mobility spectrometry explosives detection technology was first tested at U.S. airports, authorities quickly realized how many people carried nitroglycerin as a heart medication. The solution to those false alarms was to add a simple question to the screening process: Screeners began asking passengers if they were on any medications.
“There are ways to sort of dice out whether there may be other benign reasons for a positive hit,” Hallowell added. “If you’re in an environment where you’re looking for a potential drug lab, and all the necessary paraphernalia is present, and your wipes are lighting up like Christmas trees, there’s white powder everywhere, I think you have a pretty good situation to sort of go to the next level. Most law enforcement officers have a good sense of what a suspicious situation looks like. If you go in with your eyes wide open and understand there’s no such thing as a 100% solution, you can minimize the false alarms.”
Trace Eye-D is working on that too. While things aren’t yet far enough along to reveal details, the company is beginning a project in a non-forensics area it hopes will lead to the development of new colorimetric formulas that could eliminate false positives altogether.
More on that is expected in 2025. For now, a simpler, safer and more cost-effective method of colorimetric field testing of suspected illegal drugs can improve the process for law enforcement.
For more information, visit Trace Eye-D.
