Comparison of GC-MS and TLC techniques for asarone isomers determination

Two chromatographic methods (GC-MS and TLC) have been developed for separation and determination of cc and beta asarone from essential oils and alcoholic extracts. The study has been performed on the Acorus calamus (I) and Asarum europaeum (II) essential oils of Romanian origin and the alcoholic extract of Acorus calamus L (III) and it is a consequence of the International Boards exigency regarding the presence of beta asarone in food, beverages and pharmaceuticals. The isomers were determined using both internal and external standard methods. Both SIM and SCAN techniques were used and the results were compared regarding the chromatographic resolution and interference compounds. The method exhibits good repeatability and low detection limit but is expensive and time consuming. The two isomers concentrations are 5.2-6.7 mu g ml(-1) (I), 460-510 mu g ml(-1) (II) and 2.7-5.7 mu g mi (III) for alpha asarone and 91-98 mu g ml(-1) (I), 24-29 mu g ml(-1) (II) and 88-97 mu g ml(-1) (III) for beta asarone. The TLC method was developed as an alternative for the GC method. The separation was performed on silica gel plates using toluene: ethyl acetate 8:2 as mobile phase. The evaluation of the chromatograms was made by densitometry using multiple wavelength. The sum of the two isomers are between 80-120 mu g ml(-1) (I) and 127-145 mu g ml(-1) (III) using spectrophotometric detection and between 73-93 mu g ml(-1) (I) and 99-105 mu g ml(-1) (III) using fluorimetric detection. The results of the two chromatographic methods were compared. Even the GC is more sensitive, mathematical computations for spots optimization and interference elimination could improves the TLC quality results. (C) 1998 Elsevier Science B.V. All rights reserved.