An efficient and sensitive method on the identification of unsaturated fatty acids in biosamples: Total lipid extract from bovine liver as a case study

Unsaturated fatty acids (UFAs) are fatty acids with one or more carbon-carbon double bonds (C=C). They are building blocks of structurally complex lipids. According to the position of C=C bond in the UFAs, there are multiple isomers with different physiological activities. Therefore, an accurate understanding of UFAs is essential. Combining Paternò-Büchi (PB) reaction with tandem mass spectrometry (MS/MS) analysis has been successfully used to identify unsaturated lipids in bio-samples. However, there are still some challenges, such as low reactive rate and low MS response of PB products. In this study, 3-pyridinecarboxaldehyde (3-PYA) was selected as an efficient PB reagent for the first time. According to the nitrogen rule, introduction of nitrogen did not only make the target MS and MS/MS ions to be easily identified but also increase the ionization efficiency significantly. The developed method in this study demonstrated greater efficiency and sensitivity for the identification of UFAs in total lipid extracts from bovine liver compared with other commonly used PB reagents.