2 Jun 2017

Fast and simple identification of legal highs using FTIR spectroscopy

Legal highs are drugs that contain a variety of chemical ingredients, specifically manufactured to keep them off the list of controlled substances. Some of these ingredients are illegal, and some are not, making it challenging to classify these drugs.


Legal highs are drugs that contain a variety of chemical ingredients, specifically manufactured to keep them off the list of controlled substances. Some of these ingredients are illegal and some are not, making it challenging to classify these drugs.

Read our application note on the analysis of cannabis and cocaine using the Quest ATR spectrometer accessory.

Also known as new psychoactive substances (NPS) [1], these “highs” are designed to produce similar effects to drugs like cocaine, ecstasy, and cannabis. They can be addictive, and pose a serious threat to public health. They can even be fatal [2].

Because the ingredients have not been tested, users can’t be sure of their effect. Often, the drugs themselves don’t match their label claim [3], so the identity of the active ingredient(s) is questionable. In addition to this the online availability of legal highs has increased, making them more of a threat than before.

Law Enforcement and Hospitals need a Fast and Effective Identification Method

As the distribution of these substances increases, it is becoming more important to be able to quickly identify new synthetic compounds. It’s critical for law enforcement [4] to be able to identify the precise composition of legal highs, for use as evidence in a courtroom. And hospital staff need a reliable way of analyzing these substances to prescribe accurate overdose treatment.

However, identifying and analyzing these drugs can be difficult. This is due to their inconsistent chemical make-up – they don’t match their label claim - and the fact that they contain a wide variety of additives and impurities. Also, the labs that create these drugs alter them whenever they’re declared illegal, making them hard to track and legislate.

Using FTIR Spectroscopy to Identify Legal Highs

The novel psychoactive substances found in legal highs are chemically similar to illegal drugs, like cocaine and ecstasy. Their composition is altered just enough to circumvent the law, which raises legal issues with prosecution [4]. The list of illegal substances is constantly evolving in response to the introduction, and subsequent gains in popularity, of different legal highs.

This means that the legal high landscape, and legal frameworks associated with it, is constantly shifting. Because of this accurate chemical identification is a necessity; either to determine if a confiscated substance is illegal or, in a clinical setting, to establish the cause of an overdose.

The analytical methods used to ID legal highs need to be non-destructive (so samples can be presented as evidence), as well as fast and easy-to-use by a non-expert. They also need to be easily deployed in the field, and not just confined to a lab. In addition to this the specific technique needs to provide exact information on the chemicals structural properties, such as isomeric and stereo-chemical specificity.

FTIR (Fourier Transform – Infrared Spectroscopy) is considered a “Category A” technique by the Scientific Working Group for the Analysis of Seized Drugs (SWGDRUG), due to its high discriminating power [5].

This is because FT-IR is an extremely fast technique which is entirely non-destructive [4,6]. It allows the user to easily identify, and distinguish between, various compounds within a drug sample. This makes it ideal for law enforcement officers and hospital staff, who don’t have the time or expertise to use complicated equipment.

Comparison of Molecular Fingerprints for Accurate Substance Identification

A multitude of studies have demonstrated that FT-IR is an appropriate technique for the identification of unknown substances. When used alongside reference libraries FT- IR can be used to compare a substance’s molecular fingerprint against thousands of others to rapidly identify drugs in seized materials [4,7].

Using an advanced ATR (Attenuated Total Reflectance, a method of FT-IR analysis) correction algorithm, the researchers have correctly identified samples with a probability of 93%.

Research has also shown how FTIR spectroscopy can be quickly and easily used in the field by non-specialists. In one study, handheld instruments were used to perform analysis on a white powder found at a clandestine laboratory. The results of searching the external ATR reference library produced a best match to 3-methylmethcathinone (3-MMC) hydrochloride with a probability of 93%. The result: “A very good match was obtained for a spectrum acquired in the field from a sample of questionable purity.”

The authors confirmed the effectiveness of FT-IR spectroscopy for analyzing legal highs, stating: “ATR spectroscopy is becoming the technique of choice for rapid infra- red spectral analysis.”

The Ideal FTIR System for the Analysis of Legal Highs

The Golden Gate diamond and Quest ATR spectrometer accessories, offered by Specac, can be used to rapidly and accurately analyze legal highs.

The Golden Gate ATR FTIR accessory is the world’s most versatile infrared sampling system, and is suitable for high-throughput quantitative and qualitative analysis. This means it can be used for both rapid drug identification and for more in-depth analysis following the seizure of the illegal substance.

The Quest ATR accessory is simple and easy to use, making it the choice of many non- expert users. It’s simple design means it can be used rapidly by law enforcement or hospital officials with no need for training.

Both accessories are inexpensive, user-friendly, need little or no sample preparation and are non-destructive.


[1] “What exactly are legal highs?” BBC News http://www.bbc.com/news/uk-32857256

[2] “The Human Cost of Cheap Highs: A Journey into Britain's Most Addicted City” Independent.co.uk, 2016 http://www.independent.co.uk/news/uk/home-news/legal- highs-law-banned-thursday-psychoactive-substances-act-critics-professor-nutt- a7035951.html

[3] M. Baron, M. Elie and L. Elie “An Analysis of Legal Highs: Do They Contain What It Says on the Tin?” Drug Test Anal. 2011, 3(9):576-81. DOI: 10.1002/dta.274.

[4] S. Lowry, M. Bradley, and W. Jalenak, “Identifying Synthetic Designer Drugs Using FT-IR, Raman, and GC–IR” Spectroscopy, 2014, 29, 8

[5] SWGDRUG Recommendations Edition 6.1 (2013-11-01), www.swgdrug.org

[6] V.M. Zancajo, J. Brito, M.P. Carrasco, M.R. Bronze, R. Moreira and A. Lopes, “Analytical Profiles of "Legal Highs" Containing Cathinones Available in the Area of Lisbon, Portugal”, Forensic Sci Int. 2014, Nov; 244:102-10. DOI: 10.1016/j.forsciint.2014.08.010

[7] S. Angelos and M. Garry, Forensics Magazine, 2011, 08, 5

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