I don’t know any labs that test for quality per se, most test for bacterial, fungal, heavy metal contamination, You can only test an herb for marker compounds, or isolated chemical like berberine, which often have little relationship to quality. Quality can be determined via organoleptic testing (taste, color, odor, freshness, botanical ID, etc). You can also do HPLC’s which most labs do, but they are comparing your sample to samples they have run before and if the samples are not great quality , then your herb may not match.