Comparison of two direct methods for the determination of fatty acids in human milk

We have validated and compared two direct methods for determining by capillary gas chromatography fatty acid composition in human colostrum and one method that involved lipid extraction and then methylation. Direct Method I (DMI) consisted of transesterification of fatty acids using acetyl chloride. Direct Method 2 (DM2) used boron trifluoride-methanol as esterification reagent. The two direct methods were compared with a traditional methylation method that involves prior lipid extraction. We found that there were no differences between the direct methods and the traditional method. We then validated both direct methods: recovery rates, inter-assay and intra-assay precisions were determined with satisfactory results. Both methods gave similar results, but DM2 has certain advantages over DM1, such as speed, safety and better recovery rates.