3.3. Chromatographic separation
2
To get a good command of the fatty acids that may exist in NF, 34 fatty acids were chosen in this paper. 26 of them are saturated fatty acids and 8 are unsaturated fatty acids (UFAs). It is challenging to separate the 34 fatty acids in a plain HPLC column since unsaturated fatty acids often coelute with saturated fatty acids containing one or two fewer carbon atoms. C18 columns showed much better separation property than C8 columns for fatty acids. However, the separation time was quite long (more than 120 min). Therefore, C18 column was not considered for latter experiment. Several kinds of C8 columns have been compared for their separation efficiency. The results indicated that BDS C8 column in conjunction with a gradient elution could separate the 34 fatty acid derivatives within 68 min (see Fig. 2A). Thus, BDS C8 column was applied in this paper.