Studies on the concentration of oxidized components of abused fats and the application of HPLC to their separation

The efficiency of five separation techniques at removing unaltered compounds from the methyl esters of oxidized fats was compared, as were concentrations of oxidized products. A batch type distribution method using acetonitrile/hexane was the most effective in concentrating the polar products and removal of palmitate and stearate from abused fats which had been hydrogenated. The level of high molecular weight material present in samples was measured indirectly by determination of the percent elutable material via gas chromatography. A high performance liquid chromatography system developed to partially separate or “profile” the oxidized products used an octadecyl bonded phase column and a linear gradient from 50% aqueous acetonitrile to 85% aqueous acetonitrile, at a rate of 5%/min. The resultant chromatograms can be useful in assessing the quality of used fats.