A rapid multidimensional liquid-gas chromatography method for the analysis of mineral oil saturated hydrocarbons in vegetable oils

The present paper describes an investigation directed toward the development of a rapid heart-cutting LC-GC method for the analysis of mineral oil saturated hydrocarbons contained in vegetable oils. The automated LC-GC experiments were carried out by using a system equipped with a syringe-type interface, capable of both heart-cutting and comprehensive (LC × GC) two-dimensional analysis. The first dimension separation was achieved on a 100 mm × 3 mm ID × 5 μm d(p) silica column, operated under isocratic conditions (hexane). A single 30-s cut, corresponding to a 175 μL volume, was transferred to a programmed temperature vaporizer. After the large volume injection, the target analytes were separated in a rapid manner (~9 min) using a 15 m × 0.1mm ID × 0.1 μm micro-bore GC capillary. The overall LC-GC run time enables the analysis of ca. 4 samples/hour. Quantification was performed by using external calibration, in the 1-200 mg/kg range. The method was validated in terms of linearity, precision, limits of detection and quantification, and accuracy. A series of commercial samples were subjected to analysis. Various degrees of contamination were found in all samples, in the 7.6-180.6 mg/kg range.