Table 2.

Mass transitions of hydroxytyrosol and its metabolites. HT: hydroxytyrosol, Ole: oleuropein, DOPAC: 3,4-dihydroxyphenylacetic acid, HVA: homovanillic acid, HT-S: hydroxytyrosol sulphates, HT-G: hydroxytyrosol glucuronides.

Hydroxytyrosol (Metabolites)	[M − H]− (m/z)	Most Abundant Fragment (m/z) (Used for Quantification)
HT	153	123
Ole	539	275
DOPAC	167	123
HVA	181	137
HT-S	233	153
HT-G	329	153