DETERMINATION OF FREE FATTY-ACIDS IN DAIRY-PRODUCTS BY DIRECT COUPLING OF A CONTINUOUS PRECONCENTRATION ION-EXCHANGE-DERIVATIZATION MODULE TO A GAS-CHROMATOGRAPH

A flow injection ion-exchange system coupled to a gas-liquid chromatog raph was used for the determination of free fatty acids in dairy produ cts. The pretreatment module permits isolation and preconcentration of free fatty acids on Amberlite IRA-400 and derivatization of eluted ac ids with acetyl chloride in methanol. The methyl esters are continuous ly injected via the injection port to prevent losses of the more volat ile esters; they are quantified at the milligram per liter level with a FID detector. The method thus developed was applied to the determina tion of free fatty acids in milk, cream, and butter samples; fatty aci ds were also added to some samples to induce rancidity in order to ass ess the method performance.