Conjugated linoleic acid determination in human milk by fast-gas chromatography

An efficient direct method for measuring c9,t11- and t10,c12-conjugated linoleic acid (CIA) isomer content in human and rat milk was developed and validated using an RTX-2330 capillary column (40 m x 0.18 mm x 0.1 mu m). In comparison with the commonly used 100 m x 0.25 mm x 0.20 mu m columns, this new type of fast column allowed the separation of FAMEs with the same resolution but in much less time. An additional advantage for biological samples was that only a small volume of sample was needed. Two different procedures were tested in order to select the best methylation of CIA isomers, and the alkali plus acid-catalyzed procedure was selected. The precision results showed relative standard deviations (R.S.D.) of repeatability and reproducibility ranging between 0.10 and 8.71%. The application of this method to human and rat milk samples showed that it was a rapid, simple and reliable method for the analysis of biological samples. (c) 2007 Elsevier B.V. All rights reserved.