Rapid detection of vegetable oils in milk fat by on-line LC-GC analysis of beta-sitosterol as market

摘要

On-line liquid chromatography-gas chromatography (LC-GC) has been applied to the detection of vegetable oils in milk fat using beta-sitosterol as marker. The method involves transesterification of the fat, pre-separation of the sterol fraction from other lipid constituents and on-line transfer to the capillary GC system. The on-line approach avoids time-consuming sample preparation steps prior to GC analysis. The suitablity of this analytical approach was tested with model mixtures of milk fat with cotton rape-seed oil. The method allows the detection of adulterations at low levels. Simultaneous quantifiation of cholesterol in milk fat is also possible. Considering the rapid sample preparation, the described method can be applied for screening of large sample numbers.