Gas Chromatography (GC)
Gas chromatography involves the oil sample being vaporized and injected onto the head of a chromatographic column where it can be analyzed. The sample is transported through the column by a flow of chemically inert gas. Commonly used gases include nitrogen, helium, argon, and carbon dioxide. The carrier gas system also contains a molecular sieve to remove water and other impurities. This is a common type of chromatography used in analytical chemistry for separating and analyzing compounds that can be vaporized without decomposition. This is the simplest test you can have carried out on your oil and subsequently the least expensive. The results will give you an overall cannabinoid percentage and also give you the percentages broken down into THC, CBD, and CBN.
What is Gas Chromatography/Mass Spectrometry (GC-MS)
This method combines the features of gas chromatography alongside mass spectrometry to identify different substances within a test sample. GC with flame ionization or MS detection is now an established method for the analysis of cannabis. Derivatization (conversion into a derivative originating from the original to aid in identification) is necessary when information about cannabinoid acids and the dominating cannabinoids in the sample is required.
The total cannabinoid content, i.e. the number of neutral cannabinoids plus the neutral cannabinoids formed by decarboxylation of the acidic cannabinoids, is determined when the GC analysis is performed without derivatization.
What is High-Performance Liquid Chromatography (HPLC)?
This is the most expensive but thorough test you can have performed on your samples. High-performance liquid chromatography allows the simultaneous determination of neutral and acidic phytocannabinoids without derivatization. Reversed-phase columns and preferably solvent-programmed gradient systems are used for the separation of major and minor cannabinoids and their corresponding acids for genotyping (ratio acidic/neutral cannabinoids), studying the effect of manufacturing processes and storage conditions and batch comparison if required. Detection is usually performed by UV and diode array photometers, as well as by fluorescence, electrochemically, and also MS.
The laboratory will send you a lab report detailing the overall cannabinoid content and the percentages of THC, CBD, et cetera. Depending on the type of testing you have carried out the report may also include the terpene percentages and other information. The two main cannabinoids we are interested in are THC and CBD and in order to standardize the medications you are preparing obviously the overall percentage is required. For example, test results on the oil we produced from the Skunk Haze variety supplied to us by the CBD crew came back with an almost perfect 1:1 THC to CBD ratio and the overall active cannabinoid content was 80%. This allows us to accurately calculate the number of cannabinoids we add to our preparations.