Analysis of Hydroxy Fatty Acids from the Pollen of Brassica campestris L. var. oleifera DC. by UPLC-MS/MS

Ultraperformance liquid chromatography coupled with negative electrospray tandem mass spectrometry (UPLC-ESI-MS/MS) was used to determine 7 hydroxy fatty acids in the pollen of Brassica campestris L. var. oleifera DC. All the investigated hydroxy fatty acids showed strong deprotonated molecular ions [M–H] − , which underwent two major fragment pathways of the allyl scission and the β -fission of the alcoholic hydroxyl group. By comparison of their molecular ions and abundant fragment ions with those of reference compounds, they were tentatively assigned as 15,16-dihydroxy-9Z,12Z-octadecadienoic acid ( 1 ), 10,11,12-trihydroxy-(7Z,14Z)-heptadecadienoic acid ( 2 ), 7,15,16-trihydroxy-9Z,12Z-octadecadienoic acid ( 3 ), 15,16-dihydroxy-9Z,12Z-octadecadienoic acid ( 4 ), 15-hydroxy-6Z,9Z,12Z-octadecatrienoic acid ( 5 ), 15-hydroxy-9Z,12Z- octadecadienoic acid ( 6 ), and 15-hydroxy-12Z-octadecaenoic acid ( 7 ), respectively. Compounds 3 , 5 , and 7 are reported for the first time.