ISO 20122:2024

Overview

ISO 20122:2024 specifies a validated laboratory procedure for the determination of mineral oil saturated hydrocarbons (MOSH) and mineral oil aromatic hydrocarbons (MOAH) in vegetable fats and oils using online-coupled HPLC-GC-FID (high performance liquid chromatography - gas chromatography - flame ionization detection). The method targets hydrocarbons in the boiling range equivalent to n-alkanes from C10 to C50 and is designed to achieve a low limit of quantification (LOQ) for routine and regulatory testing of vegetable oil matrices.

Key topics and technical requirements

• Scope and applicability: Applies only to vegetable fats and oils (not other matrices). Demonstrated suitability for MOSH concentrations > 3 mg/kg and MOAH concentrations > 2 mg/kg based on interlaboratory studies.
• Analytical principle: Saponification of the sample, extraction of the unsaponifiable fraction, clean-up and fractionation by online HPLC-GC, solvent vapour exit to remove most solvent, and quantification by GC-FID with internal standards.
• Sample preparation steps: Includes hexane/ethanol partitioning, saponification, removal of biogenic n-alkanes (aluminium oxide treatment), clean-up before epoxidation, and epoxidation of the MOAH fraction to remove interfering olefins (ethanolic epoxidation described in Clause 8.6).
• Alternative epoxidation: Performic acid epoxidation (Annex C) is offered as an alternative for samples with strong MOAH interferences (e.g., tropical oils) and provides comparable results.
• Verification and system checks: System suitability tests, blank runs and quality control procedures are specified. In case of suspected non-fossil interferences or ambiguity, GC×GC-MS can be used to verify the fossil origin of MOSH/MOAH.
• Limitations and notes: Epoxidation can induce degradation of MOAH with three or more aromatic rings; riding peaks from biogenic hydrocarbons and natural terpenes must be accounted for in quantification.

Practical applications and intended users

• Food and feed safety laboratories performing routine monitoring of vegetable oils for mineral oil contamination.
• Quality control teams in edible oil production and refining.
• Regulatory and standards bodies requiring traceable MOSH/MOAH measurements for compliance and surveillance.
• Research laboratories studying migration of mineral oils into food contact materials or conducting method development and validation. Benefits include improved sensitivity (low LOQ), harmonized sample processing for diverse oil types, and robust procedures for handling interferences common in vegetable oil matrices.

Related standards and references

• ISO 661 - Preparation of test sample for animal and vegetable fats and oils (normative reference cited).
• EN 16995:2017 - referenced as a baseline; ISO 20122:2024 includes additional steps and system suitability specifications to achieve lower LOQs.
• GC×GC-MS techniques are recommended for confirmatory analysis when interference or origin needs verification.

Keywords: ISO 20122:2024, vegetable oils, MOSH, MOAH, HPLC-GC-FID, low limit of quantification, epoxidation, performic acid, saponification, GC×GC-MS.