Fentanyl kills.
Make that: Fentanyls kill.
The threat is plural and potent, as illicit laboratories continually concoct new forms of the drug that sidestep today’s best detection techniques and protect drug dealers from prosecution. It’s a loophole that drug dealers are quick to step through—create new drugs faster than the law and health care providers can keep track of them.
While emergency responders are on the front lines daily in an epidemic that has seen hundreds of thousands of American lives lost, they have allies in chemists at the Department of Energy’s Pacific Northwest National Laboratory.
PNNL scientists are developing ways to detect and identify not only new, previously unseen forms of fentanyl but also newer and more dangerous synthetic opioids known as nitazenes.
The PNNL team has hurdled a key barrier in the detection of other forms of fentanyl, known as fentanyl analogs, and nitazenes. Most current detection methods rely on libraries of known compounds that have already been seen and reported. When responders encounter a substance suspected of being fentanyl, either the material is tested chemically or compared to known fentanyls in a database. If there’s a match, authorities know they’ve got a fentanyl compound.
But there are many potential fentanyl analogs; PNNL chemist Katherine Schultz has calculated that billions are possible. That’s fertile ground for chemists tinkering in illegal laboratories around the world. Once a known fentanyl form has been classified by authorities, unscrupulous chemists can quickly create a new, never-before-seen version that is not in any reference library. That makes identification of the compound difficult and ties the hands of law enforcement.
Detecting drugs before they’re on the books
That’s where the PNNL technology comes in. Using a combination of mass spectrometry techniques, chemists have discovered a chemical characteristic indicative of all fentanyls tested to date. The team also discovered additional chemical traits that reveal the specific form of every fentanyl tested.
Whether the substance has been found on the streets or not—whether it’s in the reference book or not—the team can tell whether a substance is or is not fentanyl.
Recently, the team extended its work to nitazenes, a lesser-known but even more potent class of illegal drugs, and have identified tell-tale chemical signals of those drugs.
The PNNL team published its work earlier this year in a pair of publications in the Journal of the American Society for Mass Spectrometry.
“It’s a never-ending problem,” said Kabrena Rodda of PNNL, a co-author of one of the studies and a forensic toxicologist. “People who traffic opioids synthesize new compounds in the laboratory to stay ahead of detection capabilities. It’s unreasonable to think that the companies that produce the reference standards can adapt quickly enough to detect every new form. We need to evolve quickly, to keep up and remove this built-in advantage.”
While the dangers are demonstrated starkly in lives lost, they’re also borne out in sheer statistics. Standard fentanyl is about 100 times as potent as morphine; scientists estimate that nitazenes are at least 20 times even more powerful than standard fentanyl. Fentanyl is approved for medical uses as a treatment for severe pain; nitazenes are not approved by the Food and Drug Administration.
While there are test strips available to detect both substances, those are often plagued by both false positives and negatives.
The key to the PNNL system is a combination of two techniques brought together by chemist Adam Hollerbach. The first is a high-resolution commercial mass spectrometer called the Orbitrap, which gives scientists information about an ion’s mass, its electric charge and how it breaks apart. But when two molecules have the same mass, they’re hard to tell apart.
A SLIM device pays big dividends
The second technique is ion mobility spectrometry, in which scientists send ions tumbling through a sea of other molecules for anywhere from 30 to more than 180 feet on a device about the size of a very thin laptop. The SLIM device (structures for lossless ion manipulations) is like a molecular racetrack for ions to race round and round. As time goes on, the ions separate themselves out much like Olympic runners do as they space themselves out around a track. Through SLIM, scientists learn about an ion’s size and shape.
When the information from the two techniques is put together, the scientists have a thorough profile of a molecule: its size and shape, electric charge, mass and molecular formula, and fragmentation pattern.
“The more information you have about a compound, the better,” said Hollerbach, the lead investigator and author of both studies. “When you identify a person, you have multiple traits—their weight, eye color, hair color and build, for example. We’re doing the equivalent with fentanyl and nitazene compounds, using as many measurements and chemical characteristics as possible to identify each one.”
For the nine fentanyl compounds tested, the team found the same features first reported by scientist Maggie Tam showing that every fentanyl compound analyzed so far exhibits at least two tell-tale peaks in ion mobility experiments. Through its additional experiments, the PNNL team demonstrated that the two peaks associated with each fentanyl fragmented differently—an uncommon occurrence in such experiments. The team also showed that the presence of water is important for both peaks to be visible.
In a separate investigation, the team tested 14 nitazene compounds. Though nitazenes affect the same opioid receptor, their chemical structure is very different from fentanyls. The scientists found chemical signatures identifying all the compounds as nitazenes. In addition, they were able to differentiate the chemical structures of nine of the compounds based only on experimental data—something that scientists haven’t done before because many nitazene compounds are nearly identical. For the five other nitazenes, the team was able to separate the compounds into two groups of very similar structures. Even though the team knew the structures of the five nitazenes in both groups, the scientists couldn’t quite tell which pieces of experimental data correlated to which structure.
The PNNL system is largely custom built and takes about an hour to analyze each sample, too long and too expensive to be used by emergency responders. But the researchers believe that their findings could encourage the use of ion mobility-mass spectrometry systems in settings such as forensic toxicology laboratories to help gain quick and accurate answers about whether a compound is a fentanyl or nitazene compound.
The work was funded by PNNL’s m/q or “m over q” initiative—shorthand for mass divided by charge, which signifies one way that scientists measure chemical properties through mass spectrometry. A main thrust of m/q has been using computational predictions of how molecules behave during mass spectrometry analyses to create ways to identify compounds that aren’t already in reference libraries, like the team’s work on fentanyls and nitazenes.
The measurements in the study were made at the Environmental Molecular Sciences Laboratory, a DOE Office of Science user facility on the PNNL campus.
In addition to Hollerbach, Rodda and Schultz, authors of the studies include PNNL colleagues Yehia Ibrahim, Vivian Lin, Adam Huntley, Thomas Metz and Robert Ewing, as well as University of Utah chemist Peter Armentrout.
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