There are many different techniques for identifying the potency and profile of cannabis.
High-pressure liquid chromatography also known as high-performance liquid chromatography is an effective way to separate, identify, and quantify a given compound with in a mixture. Using pressure, a solvent including the sample is pumped through a column packed with stationary phase. Based on the compounds chemical interaction behavior with the solvent or stationary phase determines how fast that compound goes through the column
Due to the affinity of a given compound in the solvent mixture to the stationary silica filled column, the time a given molecule interacts with the stationary phase determines the speed at which the given molecules will go through the column. The longer it takes for a molecule to leave the column the more affinity it has for the silica than the solvent. These properties can be manipulated by changing the solvent or the bead size, shape, and/or chemistry. The molecules interaction to the silica as dictated by the solvent (except in ionic columns, is primarily as a result of the van der Waals forces among the molecules.
Several different solids can be used with chromatography. The local chemistry and particle size can be manipulated in the stationary phase to influence the speed at which the compounds are being eluted. Silica and alumina alter the most popular stationary phases utilized. Silica is preferred as it is relatively inert, it be can be used for many compounds, and it has a high sample capacity. Alumina is good for very precise elutions that require specific procedures and conditions to separation the sample mixture.
The solvents used in the mobile phase of chromatography is reliant on the polarity to the sample and stationary phase. Using a strongly polar stationary phase and a polar solvent will result in the solvents interacting with the stationary phase a lot resulting in the strong competition with polar compounds in the sample. Thus polar compounds would elute quickly. Using a non-polar solvent in this situation would allow for the polar compounds to spend more time interacting with the stationary phase and allow them to eluted slower. Silica would have the opposite affect since it is non-polar. Using polar solvents with silica would allow non polar compounds to interact longer with the stationary phase and thus elute slowly. Using as non polar solvent in this case would have the opposite effect, making non polar components in the sample to elute more quickly.
The stationary phase is more polar than the mobile phase in the normal phase chromatography method. As such the polar components in the sample will interact more with the stationary polar silica phase. In general non polar molecules will be eluted faster than polar ones. Thus the molecules can be collected by increasing order of polarity
In reverse phase chromatography, the mobile phase is more polar that the stationary phase. Thus non polar components of the sample will interact more with the stationary phase and polar compounds will be eluted first. To make the stationary phase, silanized silica is coated via covalently bound non polar liquid, usually hydrocarbons. Molecules collected with do so in decreasing order of polarity.
Normal chromatography speed is a function of gravity. To speed up the process either compressed gas is pumped into the column or a vacuum is placed at the elution end. If compressed gas is used than an inert one is usually the choice, commonly nitrogen. The more stable a gas pump output or vacuum, the more productive the chromatography.
Ionically changed media is used on the stationary phase. Do to either attracting or repelling forces of the sample the elution time will vary. Commonly sulfonate is used as a negatively charged stationary phase and quaternary amine as a positively charged media. Polar solvents are commonly used.
A ligand is bound to desired components within a sample through selective chemistry. Only compounds which are bound to the ligand bind to the column and the remaining components in the sample are washed away. The stationary phase is commonly composed of agarose or porous glass beads. To change the elution conditions, the pH or strength of the binding ligand are adjusted.
Sample components are separated by size in this technique. The stationary phase is composed of uniform pores or small silica particles or polymer. The smaller the compound the faster it elutes as it seeps through the cracks of the stationary phase better than larger compounds.
Most organic compounds absorb UV light at a couple wavelengths. This signature can be used to analyze a given elution. By shooting UV light at a given solution, not all of those wavelengths will pass through, thus being absorbed. By measuring the wavelengths that do come through, the absorbed wavelengths can be determined from the original light source. In addition the intensity of each wavelength absorbed can be determined as well to determined amount of the sample in the elution.