INFORM May 2026

AOCS METHODS INFORM 17

on February 4, 2026, n-hexane was added to the Substances of Very High Concern (SVHC) list under the EU’s REACH regulation. As a result, the analytical determination of hexane residues in food has become a central component of the ongoing safety review. Food manufacturers, ingredient suppliers, and importers may be required to demonstrate compliance using validated analytical data. Consequently, the harmonization of analytical methods is vital for scientific organizations and standardization bodies, as comparable and reliable datasets will be essential for risk assessment and future regulatory decisions. TOOLS WE HAVE: EXISTING ANALYTICAL METHODS The currently harmonized methods for determining residual hexane were developed several decades ago. AOCS Official Method Ca 3b-87, Hexane Residues in Fats and Oils, measures hexane residues in fats and oils using gas chromatography with flame ionization detection (GC-FID). It is suitable for determining hexane concentrations within a stated scope of approximately 10 and 1500 mg/kg (ppm) in fats or oils; the lower limit reflects validated working range of the method rather than an intrinsic limit of detection. The International Organization

for Standardization (ISO) has a comparable standard 9832:2002, Animal and Vegetable Fats and Oils — Determination of Residual Technical Hexane Content. For oilseed meal, analysts commonly use AOCS Official Method Ba 14-87, Total Hexane Content in Extracted Meals. The lowest validated detection level for the method is approximately 300 ppm. There is also an equivalent ISO 8892:1987, Oilseed Residues — Determination of Total Residual Hexane. In addition, ISO 9289:1991, Oilseed Residues — Determination of Free Residual Hexane, describes a method for measuring hexane that is desorbed by direct heating of the oilseed residue without prior humidification of the sample. Although these methods have served the industry well; they have limitations. Commercial extraction solvents consist of mixtures of C6 hydrocarbons, as mentioned, n-hexane and its structural isomers. Traditional HS-GC-FID methods are often used in routine analysis to add these peaks and report the result as “total hexane,” reflecting the historical regulatory focus on total residual solvent. However, modern chromatographic systems are fully capable of separating individual C6 isomers under appropriate conditions. As regulatory attention increasingly focuses specifically on n-hexane, which is associated with neurotoxicity, analytical practices may shift toward

approaches that distinguish individual components within the hexane mixture. Furthermore, most validation studies for these methods were conducted in the 10–1000 ppm range. Current regulatory discussions focus on sub ppm levels. The methods were also originally developed for oils and oilseed meals, while regulators are now considering a wider range of matrices, including processed foods and ingredients containing oils. A RENEWED INDUSTRY CONVERSATION At the 2025 AOCS Annual Meeting, in Portland, Oregon, multiple presentations addressed the evolving regulatory and scientific landscape surrounding hexane extraction. The discussions highlighted a growing awareness within the industry that hexane is entering a period of renewed technical and regulatory scrutiny. One presenter reported analyzing five different refined oil samples and detecting no residual hexane above 0.1 ppm. Potential contaminants such as MOSH and MOAH, if present at all, were estimated to occur at levels below current analytical limits of quantification, approximately 22 ppb for MOSH and less than one ppb for MOAH. Another presentation examined population exposure to hexane, suggesting that