High-performance liquid chromatography (HPLC)

High-performance liquid chromatography, or HPLC, is the standard laboratory method for separating and measuring individual cannabinoids in hemp and finished products.

A dissolved sample is pumped at high pressure through a column, where cannabinoids separate according to their affinity for the packing material, and a detector, most often ultraviolet absorbance, records each as it emerges. Because the sample is never heated, acidic and neutral cannabinoids are measured as distinct compounds. The size of each peak is compared with certified reference standards to calculate concentration.

Most potency sections on a certificate of analysis come from HPLC, and the method is typically named alongside the results. It reports each cannabinoid the laboratory has a standard for, commonly CBD, CBDA, THC, THCA, CBG, CBN and several others, then sums them into total CBD, total THC and total cannabinoids. The method is not designed to identify unknown compounds or contaminants; those questions belong to mass spectrometry and other tests.