High performance thin-layer chromatography (HPTLC) can successfully be employed for quality control of Stephania tetrandra. This paper presents two newly developed methods that are superior to those included in the Chinese Pharmacopoeia. One method, featuring an optimized Soxhlet extraction procedure, is focused on the reproducible separation/detection of tetrandrine, the main alkaloid. Using the same mobile phase [toluene-ethyl acetate-methanol-ammonia 28% (10:10:5:0.3)], this method allows identification of Stephania with high certainty and quantitative evaluation of the tetrandrine content. Quantitation by scanning densitometry is performed at 210 nm. The calibration curve is linear for 50-112.5 ng of tetrandrine per zone. A method for the detection of aristolochic acids (AAs), first published as part of the German Drug Codex, was further improved and adapted for assessing the purity of Stephania raw material. Optimized for sensitivity, this method allows detection of 1 ppm of AA that may be present due to adulteration with toxic species. Complementary to the US food and drug administration's high performance liquid chromatography-mass spectrometry (HPLC-MS) method, HPTLC on silica gel with toluene-ethyl acetate-water-formic acid (20:10:1:1) and derivatization with tin(II) chloride is a rapid and very powerful screening tool helping to ensure the safety of Stephania.
