Int. J. Pharm. Sci. Rev. Res., 28(2), September – October 2014; Article No. 41, Pages: 229-233 ISSN 0976 – 044X International Journal of Pharmaceutical Sciences Review and Research Available online at www.globalresearchonline.net © Copyright protected. Unauthorised republication, reproduction, distribution, dissemination and copying of this document in whole or in part is strictly prohibited. 229 Rania Youseff * , Lina Soubh, Zaid Alassaf Department of analytical and food chemistry, Faculty of Pharmacy, Damascus University, Syrian Arab Republic. * Corresponding author’s E-mail: ws.sarah2005@gmail.com Accepted on: 12-08-2014; Finalized on: 30-09-2014. ABSTRACT A set of samples was prepared by mixing virgin olive oil with different percentages of sunflower oil, soybean oils or cottonseed oil (5, 10, 20%). Another set of samples was prepared by mixing corn oil with different percentages of canola oil (5, 10, 20%). After two preparative steps including unsaponifiable matter determination and unsaponifiable matter fractionation by Thin Layer Chromatography (TLC), the desmethylsterols composition and content of all samples was determined in triplicate using Gas Chromatography-Flame Ionization Detector (GC-FID). The results have shown the possibility of using ∆7 stigmasterol and campesterol content to detect adulteration of virgin olive oil by sunflower oil or soybean oil, respectively. While it was impossible to detect the adulteration of virgin olive oil by cottonseed oil using desmethylsterols content even in percentages up to 15%. The results have also shown the possibility of using brassicasterol content to detect the adulteration of corn oil by canola oil. Keywords: Adulteration, Desmethylsterols, GC-FID, Vegetable oils. INTRODUCTION hecking the purity of oils is of great importance since they can be illegally mixed with cheaper oils. Therefore, authenticity of oils is necessary from the stand points of both commercial value and health aspects, accordingly, efficient analytical methods are required for authentication of oils adulteration. Therefore, different methods have been developed to detect the adulteration of vegetable oils. Some of these methods are based on the qualitative analysis of oils such as colour, triglycerides and fatty acids. 1 The content of selected phytosterols is widely accepted as one of the most important markers for the detection of adulterated vegetable oils. Phytosterols are structurally similar to cholesterol, they mainly exist in plants. 2,3 Their chemical structure is illustrated in Figure. 1. They are divided into three main groups: 4,4 dimethylsterols, 4 mono-methyl sterols and 4, desmethylsterols. Figure 1: Desmethylsterol main structure. Desmethylsterols are the most important group 4 and its most abundant products are sitosterol, campesterol and stigmasterol. 5 Those products are found in high percentages in most phytosterol sources like vegetable oils. Another sterols such as ∆7-stigmastenol and brassicasterol discriminate some vegetable oils and plant species. 6 Desmethylsterols composition and content are used for the identification of vegetable oils, regardless of their presence in lipids as minor constituents. 7 Hence, phytosterols and other unsaponifiable compounds in oils are often used as markers for the assessment of oil adulteration. 8 All over the world, there has been a high incidence of adulteration in vegetable oils, mainly in olive oil and other oils of high commercial value such as corn oil. Olive oil is adulterated in many ways because of its high price in comparison to other vegetable oils. The main vegetable oils used for its adulteration are cottonseed oil, sunflower oil and soybeen oil which are cheaper and less valuable than olive oil. 9 Numerous researchers have proposed various methods to determine adulteration resulting from the mixing of the olive oil with other vegetable oils. 9,10 Firestone et al. (1985) proposed a method based mainly on the analysis of different olive oil constituents, such as sterols, triterpenes and saturated fatty acid in the 2-position of triglyceride. 11 In our work, the method proposed in previous researches for the detection of olive oil adulteration was applied to olive oil marketed in Syria and then used for the detection of corn oil adulteration by canola oil. Results can throw light on the possibility of using desmethysterols composition for the detection of corn oil adulteration. This work also may be applied to mixtures of other vegetable oils, after changes in the data introduced to the model. Detection of Vegetable Oils Adulteration Using Desmethylsterols Composition C Research Article