Determination of saturated aliphatic hydrocarbons in vegetable oils

Abstract

The aim of this work is to inform about the development of a simple and reliable off-line method for the determination of saturated hydrocarbons (SH) in vegetable oils. sH can be used as markers for fuel or for mineral oil contamination in edible oils and fats. The method consists of the isolation of the fraction by LC on deactivated silver-silica gel and subsequent on-column GC-FID analysis. This stationary phase was prepared avoiding any kind of activation. The method was developed and validated through the participation in both a proficiency test organized by the Joint Research Centre of the European Commission, and a collaborative trial carried out with trained Spanish laboratories according to the standard ISO 5725. Results showed acceptable repeatability and reproducibility values, and Horrat index, being this protocol in use with satisfactory results ever since. The method's LOQ is 15 mg.kg-1 and its LOD 5 mg.kg-1, which make it suitable to quantify the 50 mg.kg-1 limit established by the EU, and to detect mineral oil content within the 10-500 mg.kg-1 range. Although other procedures with lower LOD have been developed throughout the years, the use of just regular laboratory equipment such as GC-FID makes the proposed method appropriate for application on a routine basis.