Application of chiral GC-MS analysis in the detection of natural products adulteration – The example of Chios mastic gum essential oil

The enantiomeric ratio of volatile compounds is characteristic in each essential oil, but it cannot be determined by usual capillary GCMS analysis. The essential oil of Pistacia lentiscus var. chia L. (Anacardiaceae), mastic oil, is a valuable product. The case of dietary and cosmetic products containing mastic oil is of great importance, due to the well-established biological activities of mastic and mastic oil [1,2], the significance of mastic gum for greek economy and the increasing international interest for such products. Numerous commercial items with a claim of mastic oil content but without certification are found in the market. In order to detect possible adulteration of this type, a method based on the separation of chiral constituents and the determination of their ratio by chiral GCMS analysis has been developed. Samples of cosmetic products (shampoos, showers gels, hand and body creams, toothpastes, soaps) and dietary products (chewing gums) from different companies were extracted with n-hexane for the retrieval of the volatile compounds and the extracts were analyzed by chiral GCMS. The results were compared with those of the analysis of 30 original mastic oil samples supplied by the Chios Mastic Gum Growers Association, as well as commercial mastic oils marketed by other companies. The main discriminating factor was found to be the (+)/(-) α-pinene ratio, which should be less than 99:1, as determined by original mastic oil analysis. Several commercial samples were found to contain much higher proportions of (-) α-pinene, an indication that commercial racemic α-pinene was used for the adulteration of the product. The use of this method to determine such type of adulterations can be helpful in establishing quality and originality in natural product commercial use.

Acknowledgement: Chios Mastic Gum Growers Association.

References: 1. Magiatis, P. et al. (1999) Planta Med 65:749–751.

2. Paraschos, S. et al (2007) Antimicrob. Agents Chemother. 51:551–559.