It is helpful to review some often used terms when addressing this question. Terms are frequently interchanged when talking about strength, potency, concentration, and dosage.
INTERPRETING YOUR LABORATORY DATA
Percent Concentration
The cannabinoid profile analysis gives you the concentration of cannabinoids expressed in %. This is the weight of the cannabinoid divided by the total plant weight. What this means is that 15% THC contains 0.15 grams of THC for every 1 gram of plant matter. Percentage is a concentration; a concentration in its simplest form is just a ratio of two things, like salt in water. The ocean, for instance, has a salt concentration of about 3.5%. This means that in a hundred pound of seawater, there are three and a half pounds of salt. The concentration can be expressed in other ways besides %, for instance, 3.5% is the same thing as 35 mg/g, or it could be expressed as 35 parts per 1000. These are all the same ratios.
Potency
Potency is an expression of the relative strength of the concentration, for instance the higher the concentration the higher the potency.
Dosage
Dosage is the concentration, multiplied by the total weight. This is a very useful tool for the dispensing of edibles.
Percent H2O
This is the weight of the water relative to the total weight of the sample. Laboratory samples are reported in both dry and wet weight. Dry weight is the standard laboratory practice, and any laboratory reporting wet weight should make an obvious disclaimer to that effect, as it will result in a lower value. The %H2O of properly cured medicinal cannabis should be between 5–15%.
Interlaboratory Results
The primary discrepancy between laboratories lies in their individual choices of instrumentation, as well as the complex chemical reactions that are taking place at the molecular level. The two options available to the chemist are, Gas Chromatography (GC), or High Performance Liquid Chromatography (HPLC). These instruments are both capable of delivering precise results in the hands of an experienced technician. The important difference between the two instruments is that the GC utilizes heat to analyze the sample, where the HPLC does not. This is an important difference because the vast majority of the cannabinoids (70% -90%), are present in the form of an acid and must be converted before consumption to their neutral form by a process
called decaryboxylation. The decarboxylation process activates the THC when it is heated. This is the same thing that occurs when medicine is smoked, when it is baked, or when a sample is analyzed by way of Gas Chromatography. The HPLC system does not heat the sample so no decarboxylation occurs. The HPLC system detects both the neutral cannabinoid of interest, as well as its acidic counterpart. Laboratories that utilize HPLC systems then combine both compounds and report them together. This system does not take into account the loss of cannabinoids by way of decomposition, and the result is a higher reported value. The two different approaches are both accurate and may be used independently as relative references inside of individual
dispensaries.
Source:
https://www.thcanalytical.com/docs/THC-Interpreting Your Data.pdf
