Improvement of saponification extraction method for fatty acids separation from geological samples

The conventional saponification method could result in lower recoveries and artificial changes of long- chain fatty acids. The main reason is the error judgment of the intermediate layer suspended between the aqueous and organic layer during the liquid-liquid extraction process. This study shows that the intermediate layer consists of lots of mediumto long-chain carboxylic salts for their special physical and chemical properties. An improved saponification extraction method is also developed and the results show that the carboxylic salts distributed in the interme- diate layer could be obtained completely, which greatly enhances the authenticity and accuracy of fatty acid anal- ysis. Additionally, the possible reasons of formation of the intermediate layer are also discussed.