On behalf of the German Spice Association, the DIN EN ISO 17043 accredited proficiency testing organisation proof-ACS carried out a laboratory comparison for the determination of MOSH/MOAH in spices. The aim of the comparative study was to evaluate the state of the art with regard to the quantification of mineral oil hydrocarbons using HPLC-GC-FID in complex matrices such as dried spices.
Due to their high natural content of saturated and unsaturated hydrocarbons, spices are among the most challenging foods with regard to the determination of MOSH/MOAH using classical HPLC-GC-FID technology. In both the MOSH and MOAH fractions, significant co-elutions with the biogenic interfering substances can occur, making it difficult to correctly interpret the MOSH/MOAH data. In the laboratory comparison study, six samples with different levels of contamination were provided for analysis, including two samples each of marjoram, cinnamon and clove.
17 laboratories participated in the study, 16 of which reported results. Laboratory Lommatzsch & Säger was the only laboratory to fulfil the comparability criteria (|z-score| ≤ 2) for all analysis parameters (six results each for MOSH and MOAH). The laboratory comparison demonstrates once again that professional expertise in terms of appropriate sample preparation and data interpretation is essential for the correct determination of MOSH/MOAH, especially in difficult matrices such as spices. Our HPLC-GC-FID chromatograms shown below demonstrate how properly processed spice samples can look like. To confirm the results, two-dimensional gas chromatography (GCxGC-MS/FID) was also used to clearly distinguish MOSH and MOAH from the co-eluting interfering substances.
