Evaluation of the uncertainty associated with the off line HPLC-GC(FID) determination of 4-desmethyl sterols in vegetable oils

► Uncertainty of determination of 4-desmethyl sterols in vegetable oils is estimated. ► From Bottom-up strategy Ishikawa diagram for identification of the sources is used. ► The methodology implies HPLC fractionation of sterols-quantification by GC(FID). ► The main source arises from chemical stages as derivatization and quantification.