engleski

Solid Phase Extraction Coupled with Capillary GC Applied to the Determination of Mono and Diglycerides of Vegetable Oils and Fermented Foods

Determination of content of monoglycerides (MG) and diglycerides (DG) and 1, 2DG/1, 3DG ratio in foods that contain a high amount of fat, is considered to be somewhat useful to evaluate the age of the product (in the virgin olive oils), the ripening stage of fermented foods (salami, cheese) or to evidentiate the possible fraud (partial neutralization of virgin oils). Several authors stated that the gas chromatographic method is one of the most suitable for the determination of MG and DG, especially if a peculiar capillary column, named TAP (Chrompack s.r.l.) is adopted, which is coated with a polar high temperature stable stationary phase. The peculiar performances of this column are the possibility of separate glycerides both on the basis of their molecular weight, and on the basis of their unsaturated degree. Sample preparation involves separation of MG and DG that, e.g., are present in small amounts in olive oil: to make this step easier and faster, a solid phase extraction (SPE) technique was applied: cartridge of amino phase (Isolute TM NH2 500 mg/3ml) were used to achieve the separation of lipid fraction into polar and non polar fraction. The application of this method admit time saving, sample amount saving (50 mg ca) and the use of few ml of solvents, that is an advantage for what is concerning concentration of solvent impurities. Another advantage is that any overloading of GLC column is avoided, caused by the high amount of triglycerides. Method was applied to olive oil, salami and cheese samples and for each of them reliability was assessed, too.

monoglycerides; diglycerides; solid phase extraction; capillary gas chromatography; olive oil; salami; cheese

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