Laboratory Methods
Infrared Spectroscopy
For The Loop, as for many other drug checking organisations around the world, infrared spectroscopy is one of our key methods of chemical analysis and has been since we started testing substances of concern. The technique is fast, portable, easily detects most substances and costs very little money per test. The Loop uses Bruker Alpha and Shimadzu ATR-FTIR instruments.
Infrared spectroscopy works by shining infrared light through the substance. Different substances absorb different wavelengths of light and the reflected light produces a unique fingerprint (spectrum) for each substance. The device software automatically matches the spectrum to a library of known substances in a matter of seconds and indicates how well the measured spectrum matches those in the database. The Loop compares spectra to several databases to ensure coverage of a large number of different substances, including New Psychoactive Substances.
If the match probability is low, another drug may be present in a tested substance. In these cases, we perform a subtraction analysis, where the spectrum of the primary drug is subtracted from the measured spectrum. This produces a second spectrum, which is matched to the library as before. This process easily identifies adulterants when they make up more than 10% of a submitted substance.
On rare occasions, the match quality is still poor and we are unable to confidently identify a substance. This typically occurs in tablets containing low amounts of an active ingredient. In these cases, the drug is extracted and recrystallised using a solvent and analysed again.
Reagent Testing
Some drugs are active at very low doses and are poorly detected by infrared spectroscopy. In these cases, we test the substance using reagents. These chemicals produce different colours when added to different substances.
Whilst reagents are highly sensitive, they only detect chemical groups and are not specific to individual drugs.
We use reagents as a presumptive test to rule-in or rule out certain substances. For example, if ecstasy tablets or LSD blotters do not produce an expected colour change upon testing, we can be confident that they do not contain the substance.
Fentanyl Testing
Fentanyl is a painkiller opioid with effects similar to morphine. This drug is estimated to be about 100 times as potent as morphine and 50 times as potent as heroin. Whilst fortunately uncommon in the UK compared with North America, fentanyl can be used to adulterate other drugs, particularly heroin and counterfeit opioid/benzodiazepine tablets. Due to its potency, fentanyl and its analogues have been responsible for an increasing number of opioid-related deaths in recent years.
The Loop is able to test substances for the presence of fentanyl. Since the dose for fentanyl is so low, it is very difficult to detect with infrared spectroscopy. Instead, the Loop uses immunoassay strips, which contain antibodies against fentanyl and work similarly to pregnancy tests and lateral flow tests used for COVID-19. In case of an incident, The Loop has access to naloxone, a medication which reverses the effects of fentanyl in under 5 minutes.
Drug Quantification using Mass Loss Analysis
The Loop uses a method called mass loss analysis (MLA) to assess the strength of tablets that have been confirmed to contain MDMA or cathinones (eg.4-CMC, 3-MMC).
The technique involves measuring the mass of a tablet before and after washing with methanol. MDMA is highly soluble in methanol, whilst the remaining components of the tablet do not dissolve. The difference in mass before and after rinsing therefore correlates to MDMA content.
MLA was developed as a rapid, portable, low cost and low technology method. Whilst the technique is not as accurate as more sophisticated techniques such as quantitative NMR, the results are within a range that enables evidence-based advice to be distributed on dosage, which also can be modified to individual service user characteristics in healthcare consultations directly with Loop health professionals. This makes MLA particularly useful when very strong ecstasy tablets are in circulation, as has been the case in the UK during the last decade.
MLA is also used to quantify the contents of tablets containing other drugs, such as cathinones like 4-CMC.
