4 Most Common Cannabis Testing Systems & Methods

A Comparison of  Chemical Makeup Testing Methods for Cannabis

The 3 major testing methods GC, HPLC and HPTLC are similar – all involve running a sample through treated silica to separate the different cannabinoids from one another, and then measuring the amounts of the different cannabinoids – but the different procedures makes the different technologies best suited for different applications aside from marijuana potency testing.

A 4th technology, the Nano Sniffer or Electronic Nose Nanotechnology can accurately measure chemicals of interest in a sample.  A 5th technology under development may one day replace the mass spectrometer, currently we use a proprietary spectrometer device to generate unique signatures of each sample we test.

We use a Nano Sniffer and/or HPTLC to quantify the chemical makeup of cannabis samples, and a spectrometer for identification via unique signatures.

Gas Chromatography

GC (Gas Chromatography) is the most common method of chemical analysis in use globally. In GC, the sample under study is vaporized and then pushed by a mix of gases through a long, thin, coated tube, not unlike a hollow fiber optic line up to 60 feet long. The different cannabinoids separate from each other as they travel, and are measured at the far end, usually by a detector known as a FID that burns whatever comes out of the tube and looks for the products of combustion. The response from the detector is compared to the response to a “reference sample” that contains a known amount of specific cannabinoids in it.

GC is terrific for measuring small quantities of cannabinoids. It’s main weakness is that, because the sample is vaporized at high temperatures when it enters the machine, it cannot distinguish THC from THC-A in a sample without significant additional processing. The coated tubes are used for hundreds or thousands of tests before replacement, leading to problems from contamination and degradation of the column.

This makes the technology impractical for testing infused products.

High Performance Liquid Chromatography

In HPLC (High Performance Liquid Chromatography), the sample is pushed by liquid solvents through a short tube packed with silica particles. The separated cannabinoids are measured at the far end, usually by monitoring the output with a beam of UV (ultraviolet) light. The main weakness of this method is that the UV detector responds to many substances in addition to cannabinoids, leading to interference, and has significantly different responses to different cannabinoids, requiring repetitive calibration for each separate cannabinoid. As with GC, the columns must be re-used many times, leading to contamination and degradation problems.

High Performance Thin Layer Chromatography

In HPTLC (High Performance Thin Layer Chromatography), the sample is “spotted” onto a disposable, silica-coated plate. Liquid solvents are then run across the plate, separating out the cannabinoids. The plates are treated with chemicals and scanned at a particular frequency to reveal the cannabinoids.

HPTLC particularly lends itself to the analysis of complex mixtures, such as plant or food samples, as detection can be limited to specific groups of substances – in this case, cannabinoids – and the use of disposable plates means that no residues accumulate from one test to the next. The main limitation of HPTLC is that it is not as sensitive to minute levels of cannabinoids as GC or HPLC. However, even the most dilute medical marijuana products such as sodas and drinks contain enough cannabinoids to be accurately measured with HPTLC.

Electronic Nose Nanotechnology (Nano Sniffer)

A Nano Sniffer, possibly the most accurate cannabis testing system to date, is an electronic nose that is able to detect molecules in vapor. When a sample is placed into the testing chamber, it is analyzed using a gas-flow-over-the-sensor system that supports the chemical release process, essentially volatilizing the compounds for analysis by formulated polymer based  sensors.

The vapors cause swelling, which induces quantifiable resistance changes at a sensitivity up to 500 parts per billion. Conducting polymer sensors are coated with different films able to detect numerous analytes due to their varying reactions to those sensors. This sensors are electronically connected to an analogue and digital electronics board that reads and displays the resistance change digitally.

What Cannabis Testing Systems do we use?

At 4TM Jamaica we use a Nano Sniffer and/or HPTLC to quantify the chemical makeup of cannabis samples, and a spectrometer for identification via unique signatures.