Due to a wide variety and similar physicochemical properties of monohydroxy saturated fatty acids (OH-FAs) isomers as biomarkers, previously reported OH-FAs in environmental samples were mainly restricted to the α-, β-, (ω-1)- and ω-OH-FA isomers. Here, N,N-dimethylethylenediamine (DMED) labeling coupled with ultra-high-performance liquid chromatography-mass spectrometry (UHPLC-MS) analysis with multiple reaction monitoring mode (MRM) was developed to screen, identify and quantify position-specific isomers of OH-FAs (C8-C18). An identification strategy of positional isomers of OH-FAs, including α-, β-, 4 to (ω-2)-, (ω-1)- and ω-OH-FAs, was established by integrating the characteristics of peak intensity ratios of product ions based on the library of OH-FAs. Meanwhile, d4-DMED-labeled OH-FA standards as internal standards were adopted for the relative quantification of positional isomers. The extraction processes were optimized for different interface-environmental samples. Our method offers a promising tool to investigate position-specific isomers of OH-FAs in the land-atmosphere interface.
Figure 1: The picture presents the brief process of the developed method.
Citation: Niu, M.T.#; An, N.#; Zhang, W.X.; Hu, W.; Fu, X.L.; Kawamura, K.; Feng, Y.Q.; Zhu, Q.F.*; Fu, P.Q.* (2024) Position-specific isomers of monohydroxy fatty acids in the land-atmosphere interface: identification and quantification. npj Climate and Atmospheric Science, 7, 75. https://doi.org/10.1038/s41612-024-00621-5
