COMPARISON OF 2 METHODS FOR THE DETERMINATION OF FATTY-ACID PROFILES IN PLASMA AND ERYTHROCYTES

We have validated and compared two methods for the determination of fa tty acid profiles in biological samples by capillary gas chromatograph y. Method I consisted of a previous lipid extraction and esterificatio n of fatty acids using boron trifluoride-methanol. Method II was a dir ect method that combined extraction and esterification of freeze-dried samples in a single step, using acetyl chloride as the reagent. The t wo methods were applied to the analysis of plasma and erythrocyte samp les. Both methods gave similar results in plasma, whereas in erythrocy tes, the direct method gave significantly higher contents of total fat ty acids. Precision and recovery rates were determined and the results were satisfactory. Detection and quantification limits showed that bo th methods had excellent sensitivity. It was concluded that the direct method has substantial advantages over the conventional method, such as higher values in erythrocytes, rapidity and less possibility of con tamination or fatty acid losses. Therefore, it is preferable for the a nalysis of biological samples such as plasma and erythrocytes. (C) 199 7 Elsevier Science B.V.