Written by Rich Press
FOR POLICE, FIRST RESPONDERS, and forensic chemists, testing a suspicious
powder can present a risk of accidental exposure via inhalation. This can be
especially hazardous if the powder contains fentanyl. Now, scientists at the
National Institute of Standards and Technology (NIST) and
state forensic laboratories in Maryland and Vermont have demonstrated that a
reliable preliminary identification of the contents of a suspicious package can
be obtained without opening it, reducing the risk of accidental exposure.
The proposed method involves swiping the
outside of a baggie and then analyzing the swipe using Direct Analysis in Real
Time Mass Spectrometry (DART-MS). This approach can reliably predict
whether a package contains fentanyl, even if mixed with cocaine, heroin or other
substances. The method was described recently in Forensic
“What’s needed is a fast and safe way to screen drug evidence
so that it can be handled appropriately,” said Ed Sisco, a research chemist at
NIST and the lead author of the study. After screening, hazardous packages can
be flagged so they are opened only under a laboratory fume hood.
Traditional colorimetric tests
require that the tester open a package and scoop out a bit of powder for
testing. Many police departments now discourage or prohibit these tests in the
field for safety reasons. Instead, officers must send the suspected drugs to a
crime lab, then wait for a result before getting a search warrant or making an
Amber Burns, manager of the Maryland
State Police forensic chemistry lab and a co-author of the study, said that she
gets a lot of rush requests, and each request currently requires a full work-up
of the evidence. Her lab plans to install a DART-MS instrument to do the quick
screening, which should speed up the process considerably. “They just need to
bring me the swipe, and they can be on their way in two minutes,” she said.
Ion Mobility Spectrometry (IMS) instruments,
which are small enough to fit in a police vehicle, could provide a viable
approach for field testing. Wherever the screening is done, it provides only a
preliminary identification. To bring a criminal case to court, a complete
work-up using standard laboratory equipment would still be necessary.
To conduct this study, the NIST
scientists teamed up with Burns and her counterpart at the Vermont Forensic Laboratory,
Rebecca Mead, who was also an author of the study. When suspected drug evidence
arrived at their labs, Burns and Mead swiped the outside of the packages. Most
were plastic baggies, though they also included envelopes, tinfoil, and pill
bottles. The chemists also dissolved a small amount of the suspicious material
in alcohol and put a drop of the resulting solution onto a second swipe for
comparison. They then sent the pair of swipes to NIST for analysis.
The NIST authors received swipes from
191 suspicious packages, which they analyzed using DART-MS and liquid
chromatography-mass spectrometry (LC-MS/MS). Those swipes contained an array of
illicit drugs, including several fentanyl analogs, heroin, cocaine,
methamphetamines, and ketamine. Many of the cocaine and heroin samples included
smaller amounts of fentanyl. The swiped packages also contained plant material
sprayed with synthetic cannabinoids, which are often marketed as K2 or Spice.
Two of the packages contained carfentanil,
which can be particularly dangerous if accidentally inhaled. Carfentanil is
roughly 5,000 times as potent as heroin.
The authors found that swiping the
outside of a package correctly predicted its contents 92% of the time. For
samples containing fentanyl and other opioids, the outside of the package predicted
the contents in all cases. Therefore, if the goal is to flag
fentanyl-containing packages for special handling, the technique appears to be
The 8% of non-matches involved cases
where several bags of different material were placed together by police into a
single evidence bag, allowing for cross-contamination. Also, the technique did
not work in most cases involving plant material in heat-sealed bags.
This study builds on previous
research by NIST scientists proving the concept of testing with an
external swipe. This new study is the first to quantify the effectiveness of
the method. It is also novel in that it used real casework samples, making this
the first field test of the method.
This swipe technique will do more
than help police get faster answers when investigating drug crimes. It will
also help at crime labs. At the Maryland lab, Burns said that upon receiving
evidence they use color tests—the same tests that officers once used in the
field—to quickly get an idea of what’s in the bag so they can line up the right
types of laboratory analysis. But those color tests don’t detect many of the
new designer drugs that make up an increasing fraction of the caseload.
The swipe test will work for this,
however. “We plan to use this to optimize our whole workflow,” Burns said.
Rich Press is
science writer and public affairs specialist with the National Institute of Standards and Technology.