ISO 3594:1976

Milk fat — Detection of vegetable fat by gas-liquid chromatography of sterols (Reference method)

The method consists in preparing of sterol digitonides and dissolving in a mixture of formamide and dimethylformamide, extraction of the liberated sterols with pentane, separation of the sterols using a suitable gas chromatograph. If, on the chromatogram, a peak with the retention time of beta-sitosterol is obtained, the presence of vegetable fat in the sample is demonstrated. Peaks of other phytosterols may support this conclusion.