HPLC (High-Performance Liquid Chromatography)

HPLC is the workhorse analytical technique for both identity and potency testing of vitamins, minerals, amino acids, and many botanical actives. The instrument pumps a liquid sample through a packed column at high pressure; compounds elute at characteristic retention times and are detected (typically UV or mass spectrometry) to produce a quantitative result. HPLC is the most common method cited on supplement Certificates of Analysis. Under 21 CFR §111.75, identity testing of incoming dietary ingredients must use scientifically valid methods; HPLC is broadly accepted when the specific method (column, mobile phase, detection) matches a published reference such as a USP monograph or AOAC Official Method.