This document specifies a method for the determination of saturated and aromatic hydrocarbons (from C10 to C50) in feed. The method has been interlaboratory validated with on-line-HPLC-GC-FID – see [1], [2] and [3]. This method is not intended to be applied to other matrices.
The method can be used for the analysis of mineral oil saturated hydrocarbons (MOSH) and/or mineral oil aromatic hydrocarbons (MOAH).
The method is applicable for feed materials, in particular vegetable oils and other fat rich feed materials, compound feeds and pre-mixtures. It is not applicable to additives or deodistillates.
NOTE 1 The method was not designed for encapsulated matrices.
The method has been tested in an interlaboratory study via the analysis of both naturally contaminated and spiked samples (pre-mixture, soybean meal, sunflower seeds, chicken feed, pig feed, vegetable oil) ranging from 3 mg/kg to 286 mg/kg for MOSH and from 1 mg/kg to 16 mg/kg for MOAH.
According to the results of the interlaboratory study, the method has been proven suitable for MOSH and MOAH mass concentrations, each above 10 mg/kg. However, the method was not fully validated during the collaborative study for the premixture sample due to too low concentrations of MOSH and MOAH. The method was also not fully validated during the collaborative study for the sunflower seeds sample due to a too low concentration of MOAH.
NOTE 2 The conclusions regarding MOAH are based on 4 analyte / matrix combinations while the IUPAC protocol [4] expects this to be a minimum of 5.
In case of suspected interferences from natural sources, the fossil origin of the MOSH and MOAH fraction can be verified by examination of the pattern by GC-MS.
For the determination of MOSH and MOAH in edible fats and oils, another CEN standard is also available: EN 16995. For more information see [5].
Annex C proposes a manual alternative method to on-line HPLC-GC-FID analysis that can be used as a screening method for the determination of MOSH.