Sophisticated drug analysis instruments including handheld narcotics analyzers, have been primary tools in the hands of law enforcement for detecting and offering on-the spot identification of substances in the field at interdictions. Some of these handheld instruments incorporate both Raman and FTIR into a single unit. These two spectroscopies are complementary techniques and enhance the ability of a user to identify unknown substances in the field. FTIR and Raman spectroscopy are excellent analytical techniques for identifying illicit drugs in pure form and in high concentrations in mixtures as well as identification of analogs, and precursors.
However, in recent years the occurrence of low concentrations (1 – 10 wt%) of illicit drugs such as fentanyl, fentanyl analogs, and heroin in powdered mixtures and pills has risen. Detection of these narcotics in lower concentrations with standard FTIR and Raman spectroscopies is difficult, because Raman and FTIR really are considered bulk detection capabilities, reliable for drugs in concentrations 10 wt% or greater, but not as easy for concentrations below that.
With narcotic quantities making up such a small proportion of the total weight of the chemical that officials are trying to identify –almost down to trace quantities – the technical capabilities of Raman and FTIR are at the edge of effectiveness. A bag of white pills containing carfentanyl in grain amounts might identify as acetaminophen, for example, yet contain enough carfentanyl in each pill to kill someone even though the amount is so small that the analyzer quite literally can’t ‘see’ it.
There is technology now that takes Raman instruments to a new level – a lower level that is – to accurately detect these lower drug concentrations in the field. SERS, or Surface-Enhanced Raman Spectroscopy, also known as Surface-Enhanced Raman Scattering, is a technology that’s been around for a while, but when combined with the existing capabilities of the analyzer, it suddenly makes it possible to regularly and reliably identify concentrations below 10 weight%, and in certain circumstances, chemicals down to 1% by weight in a given sample, which borderlines on trace capability. SERS requires handling and consumables, isn’t as affective as mass spectrometry but doesn’t have mass spectrometry’s drawbacks, e.g., it’s easy to use in the field. It’s also arguably a better solution because it can do other jobs too, e.g., bulk detection, and it is anti-fluorescent.
SERS is an analytical technique whereby molecules of a substance are first absorbed onto the surfaces of nanostructures such as nanoparticles or roughened metal surfaces. The surfaces are typically gold and/or silver. These absorbed molecules can then show an enhanced Raman scattering signal when illuminated with the laser used in a typical Raman spectrometer. This enhanced signal can be several orders of magnitude larger than a “normal” Raman signal, thus allowing for the detection of low concentrations of illicit drugs in mixtures and pills.
Just because a synthetic drug is of low concentration in a given sample of material does not make it less deadly or dangerous. What it does instead is make it difficult to detect using even sophisticated analyzer equipment that is not designed to ferret out nearly trace quantities of highly potent synthetic opioids. With low concentrations of very toxic drugs becoming increasingly common, analyzers utilizing SERP are a valuable addition to the analytical detection and identification toolbox of law enforcement and border protection and will doubtless save lives.
- Read the white paper: Lesser and Lesser becoming Deadlier and Deadlier: Detecting Low Doses of Lethal Opioids
- Watch a video showing the technology in action