Development of rapid extration methods and hyphenated techniques for determinaqtion of mineral oil hydrocarbons: the focus on MOSH and MOAH in foods

The term ‘mineral oil’ is used to indicate a wide range of products, primarily manufactured from crude petroleum through distillation processes and various refining steps. Mineral oils are mainly composed of MOSH (mineral oil saturated hydrocarbons), including n-alkanes, isoalkanes and cycloalkanes, and MOAH (mineral oil aromatic hydrocarbons), mainly consisting of alkylated PAHs. Food can get highly contaminated with mineral oil coming from packaging, especially when recycled fibres or mineral oil based printing inks are used. Depending on the complexity of the matrix to analyze, the extraction step can be more or less demanding. Traditional sample preparation methods (classical solvent extraction, saponification and acid hydrolysis) are usually applied. Rapid extraction methods, such as microwave assisted saponification (MAS) or extraction (MAE) and pressurized liquid extraction (PLE), have been recently developed. Combining elevated pressure and temperature, these methods allow for a time savings over conventional extraction methods. Some data concerning extraction methods comparison are reported. After the extraction, a purification/separation step is necessary to isolate the fractions of interest from the bulk of the matrix (mainly triglycerides). For this purpose, both off-line and on-line methods based on the ability of silica gel or silver silica gel to retain fat, are available. Off-line purification/separation can be performed using solid phase extraction (SPE) cartridges packed with silver-silica gel followed by a large volume injection and gas chromatography-flame ionization detection (GC-FID). However, the most applied method is the on-line coupling of high performance liquid chromatography to GC (LC-GC) described by Biedermann et al. [1]. Starting from this method, a fast LC-GC method that allows increasing the sample throughput and reducing solvent consumption for mineral oil determination, was recently proposed. A total time and solvent reduction of 34 and 23 %, respectively, was obtained by speeding up the gas chromatographic run and reducing the reconditioning liquid chromatographic step. The possibility to use the multi-transfer mode to further reduce the solvent consumption was also explored. A series of real samples (paperboards and pasta) were analyzed obtaining comparable results using both the reference and the proposed method.