Analytical Techniques
Analytical Techniques
Much like other regulated industries, cannabis growers and producers are realizing the necessity to incorporate modern analytical testing technologies into their process, in each step from plant cultivation to final QC. This analytical information helps drive efficiency improvements by optimizing growing conditions, increasing harvest yields, profiling active compounds, efficiently extracting compounds of interest, testing for contaminants, and ultimately delivering safe products.
Here is a brief description of many of the scientific analytical techniques that are proven tools for generating the types of data necessary for process optimization, product quality and stability, and labeling.
Common Analytical Laboratory Technologies
Flame Ionization Detection (FID)
Fluorometry
Gas Chromatography (GC)
Gas Chromatography-Mass Spectrometry (GC-MS)
Head Space-Gas Chromatography (HS-GC)
High Performance Liquid Chromatography (HPLC)/Ultra Performance Liquid Chromatography (UPLC)
Inductively-Coupled Plasma (ICP)
Inductively-Coupled Plasma- Mass Spectrometry (ICP-MS)
Infrared Spectroscopy (IR)
Mass Spectrometry (MS)
Supercritical Fluid Chromatography (SFC)
Supercritical Fluid Extraction (SFE)
Flame Ionization Detection (FID)
Flame ionization detection (FID) is a technique for measuring an analyte in a gas stream. It is frequently used as a detector in gas chromatography. The operation of FID is based on the detection of ions formed during combustion of organic compounds in a hydrogen flame. The generation of these ions is proportional to the concentration of organic species in the sample gas stream.
The use of Gas Chromatography when coupled to Flame Ionization Detection (FID), permits the analysis of a large variety of cannabinoids with very high resolution.
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Fluorometry
Fluorescence spectroscopy (also known as fluorometry or spectrofluorometry) is a type of electromagnetic spectroscopy that analyzes fluorescence from a sample. It involves using a beam of light, usually ultraviolet light, that excites the electrons in molecules of certain compounds and causes them to emit light; typically, but not necessarily, visible light.
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Gas Chromatography (GC)
Gas chromatography (GC) is used in analytical chemistry for separating and analyzing compounds that can be vaporized without decomposition. Typical uses of GC include testing the purity of a particular substance, or separating the different components of a mixture (the relative amounts of such components can also be determined). In some situations, GC may help in identifying a compound. In preparative chromatography, GC can be used to prepare pure compounds from a mixture.
GC is a widely used analytical tool for cannabis testing, particularly useful for potency testing, terpenes profiling, pesticide screening, and residual solvents analysis
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Gas Chromatography-Mass Spectrometry (GC-MS)
Gas chromatography–mass spectrometry (GC-MS) is an analytical method that combines the features of gas-chromatography and mass spectrometry to identify different substances within a test sample.
GC/MS is the method of choice for creating Cannabis profiles and signatures (chemical fingerprints), a tool for attributing the country of origin, the conditions of cultivation (indoor, outdoor), etc.
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Head Space Microextraction -Gas Chromatography (HS-GC)
Headspace sampling is essentially a separation technique in which volatile material may be extracted from a heavier sample matrix and injected into a gas chromatograph for analysis. Volatile sample components are diffused into the gas phase, which resides above the sample itself in the vial.
Headspace microextraction combined with GC is a useful tool to analyze cannabinoids in cannabis samples.
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High Performance Liquid Chromatography (HPLC)/Ultra Performance Liquid Chromatography (UPLC)
High-Performance/Ultra-Performance Liquid Chromatography is a technique in analytical chemistry used to separate, identify, and quantify each component in a mixture. It relies on pumps to pass a pressurized liquid solvent containing the sample mixture through a column filled with a solid adsorbent material. Each component in the sample interacts slightly differently with the adsorbent material, causing different flow rates for the different components and leading to the separation of the components as they flow out of the column.
Analysis by HPLC/UPLC has proven to be a reliable and accurate method of measuring active components in Cannabis products.
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Inductively-Coupled Plasma- Mass Spectrometry (ICP-MS)
Inductively coupled plasma – mass spectrometry (ICP-MS) is an elemental analysis technology which is capable of detecting metals and several non-metals at concentrations as low as one part in 1015 (part per quadrillion, pp.) on non-interfered low-background isotopes. This is achieved by ionizing the sample with inductively coupled plasma and then using a mass spectrometer to separate and quantify those ions.
The analysis of mineral and additional trace metal screening of medicinal and recreational cannabis, as well as related products, provides key labeling information. The analysis can be carried out at all stages of production to ensure product quality control and products that are free of toxic metals.
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Infrared Spectroscopy (IR)
Infrared spectroscopy (IR spectroscopy or vibrational spectroscopy) involves the interaction of infrared radiation with matter. It covers a range of techniques, mostly based on absorption spectroscopy. As with all spectroscopic techniques, it can be used to identify and study chemicals, including cannabinoids from Cannabis sativa L. Samples may be solid, liquid, or gas.
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Mass Spectrometry (MS)
Mass spectrometry (MS) is an analytical technique that ionizes chemical species and sorts the ions based on their mass-to-charge ratio. In simpler terms, a mass spectrum measures the masses within a sample. Mass spectrometry is used in many different fields and is applied to pure samples as well as complex mixtures.
MS is a critical tool for analysis of a wide variety of substances in cannabis, especially chemical residues such as pesticides. It can be combined with liquid chromatography (LC), gas chromatography (GC) and inductively coupled plasma (ICP) separations. Â LC/MS is primarily used for the quality-control detection of pesticides, whereas GC/MS is used for volatile pesticides, terpenes and residual solvents. ICP/MS is useful for analyzing heavy metals, which typically come from the soil that the cannabis grows in.
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Supercritical Fluid Chromatography (SFC)
Supercritical fluid chromatography (SFC) is a form of normal phase chromatography that uses a supercritical fluid such as carbon dioxide as the mobile phase. It is used for the analysis and purification of low to moderate molecular weight, thermally labile molecules and can also be used for the separation of chiral compounds. Principles are similar to those of high-performance liquid chromatography (HPLC), however SFC typically utilizes carbon dioxide as the mobile phase; therefore, the entire chromatographic flow path must be pressurized. Because the supercritical phase represents a state in which liquid and gas properties converge, supercritical fluid chromatography is sometimes called convergence chromatography.
SFC is ideal for testing the potency of delta-9-tetrahydrocannibinol (THC), as well as tetrahydrocannabinolic acid (THCA), cannabidiol (CBD), cannabidiolic acid (CBDA) and cannabinol (CBN). It is also good for the analysis of complex mixtures comprised of analytes, which may range in polarity. SFC separates samples efficiently at lower temperatures and limits thermal degradation.
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Supercritical Fluid Extraction (SFE)
Supercritical Fluid Extraction (SFE) is the process of separating one component (the extractant) from another (the matrix) using supercritical fluids as the extracting solvent. Extraction is usually from a solid matrix, but can also be from liquids. SFE can be used as a sample preparation step for analytical purposes, or on a larger scale to either strip unwanted material from a product (e.g. decaffeination) or collect a desired product (e.g. essential oils). Carbon dioxide (CO2) is the most used supercritical fluid, sometimes modified by co-solvents such as ethanol or methanol. Extraction conditions for supercritical carbon dioxide are above the critical temperature of 31 °C and critical pressure of 74 bar. Addition of modifiers may slightly alter this.
CO2 extraction is considered to be the cleanest, safest method for extracting plants such as hops, cannabis and a wide range of nutraceuticals and organic crops. The Supercritical CO2 extraction process creates phase changes in carbon dioxide utilizing temperature and pressure. CO2 is known as a “tunable solvent†making it extremely versatile for creating a multitude of end products by controlling temperature and pressure. These phase changes create an environment to drop out differing weights of components in the plant material.