A NIST analysis of 4,563 drug residue samples, collected nationwide between January 2024 and June 2026, maps how the toxic adulterants mixed into illicit fentanyl vary by U.S. region and shift over time. NIST chemist Edward Sisco and his colleagues published the work in Drug Testing and Analysis on Oct. 7, 2026 (DOI: 10.1002/dta.70164).

The measurement backbone is Direct Analysis in Real Time Mass Spectrometry, or DART-MS. It identifies trace amounts of unknown compounds in seconds.

Why the adulterants matter clinically

Most of the harmful compounds in the illicit fentanyl supply are not opioids. Naloxone-style reversal therefore does not address them; they require additional medical treatment to counteract their effects. One adulterant, the veterinary anesthetic xylazine, causes leg or arm wounds so severe that amputation may become necessary if they go untreated.

Alerting first responders to which adulterants dominate their local supply can, in the authors' framing, make the difference between life and death. That alerting role requires chemical identification fast enough to keep pace with a supply that changes by the month.

How DART-MS shortens the workflow

Conventional mass spectrometer systems in forensic and public health laboratories take tens of minutes per sample. The bottleneck is sample preparation: material must be vaporized and pass through a coated chromatography column before the detector sees it.

DART-MS bypasses that step. The instrument ionizes the sample directly, and the mass spectrometer produces a unique chemical fingerprint for each compound present — including trace-level adulterants — in seconds. That speed is what lets the NIST team process thousands of samples and report near-real-time compositional data instead of retrospective summaries.

What the study covers

The sample set spans both the eastern and western United States, giving the researchers a view of how quickly an adulterant established in one region spreads to others across the two-and-a-half-year window.

"We are now tracking fentanyl additives over a wide geographic area," Sisco said, "so we can see the movement of some of these additives over time, for example, from Philadelphia, down to Delaware and Maryland, and then out west."

The work sits inside NIST's Rapid Drug Analysis and Research program, RaDAR, which partners with public health agencies, law enforcement, forensic laboratories and medical examiner offices across the country. Researchers and healthcare providers otherwise have very little data on the complex chemical mix in the U.S. illicit drug supply; RaDAR positions itself as the near-real-time data source filling that gap.

"RaDAR enables NIST to immediately alert public health officials to the presence of new adulterants in their area, so that they can plan a more effective treatment for people who have consumed fentanyl," Sisco said.

From tracking to prediction

Sisco and his collaborators are now building models of adulterant movement from one region to another. "Our goal is that if some new additive pops up, say in Philadelphia, we'll be able to tell public health officials when that additive is likely to show up in Delaware, Maryland or the West Coast," he said.

Two follow-on surveys are already planned: one covering additives in ketamine, an anesthetic that has increasingly entered the illicit market, and another examining a new class of opioids known as orphines, some of which are more potent than fentanyl.

The adoption question

The study's practical value depends on whether public health and forensic laboratories adopt DART-MS screening at their own scale, or whether regional surveillance remains centralized at NIST. For instrument buyers in public-safety labs, the relevant trade is clear: seconds per sample without chromatography, against the confirmatory rigor of conventional methods. Which model states choose will determine whether adulterant alerts reach frontline responders in days rather than quarters.