Optimized and validated HPLC methods for compendial quality assessment.: IV.: Non-chiral and chiral purity tests for solanaceous (tropane) alkaloids

The main alkaloids of certain plants of the Solanacea family, such as atropine and scopolamine, together with the synthetic homatropine and methylhomatropine, are routinely used medicinal agents and have their monographs in the modern pharmacopeias. In these monographs, non selective chemical reactions and/or TLC serve for the detection of "foreign alkaloids, related substances, etc." impurities. In the present paper selective HPLC methods for the compendial purity control of these alkaloids are published. The methods allow the detection of 0.05 mu g (= 0.1 %) and the quantitation of 0.05 - 5.0 mu g of tropic acid or mandelic acid as hydrolytic degradation product impurities (chromatographic system : C-18 / methanol - phosphate buffer pH 5 - 5.5). The limit of detection is 0.025 mu g. Also, HPLC for the separation of tropane alkaloid enantiomers (chromatographic system : Chiralcel OD / n-hexane - isopropanol - methanol - triethylamine) is presented. Procedure for the enantiomeric purity control of S - ( -) - hyoscyamine, the detection of R - ( +) - distomer is suggested.