A sensitive HPLC-DAD-ESI-MS/MS method was established to screen and identify the polymethoxylated
flavonoids (PMFs) in the peels of ‘Shatangju’ mandarin (Citrus reticulata Blanco). Eight PMF standards, including four
polymethoxylated flavones, two polymethoxylated flavanones, and two polymethoxylated chalcones, were first to be analyzed in
positive mode by CID-MS/MS. On the basis of the ESI-MSn characteristics of PMFs and the results of EIC-MS/MS experiment,
32 PMFs including 24 flavones and 8 flavanones or chalcones were screened from the complex extract of the peels of ‘Shatangju’
mandarin. Among them, 10 PMFs were hydroxylated polymethoxyflavonoids (OH-PMFs), and the rest were all permethoxylated
PMFs. This was the first systematic report of the presence of PMFs in the peels of ‘Shatangju’ mandarin, especially for
polymethoxylated flavanones and chalcones. Meanwhile, the contents of the three main PMFs and total flavonoids in the peels of
‘Shatangju’ were determined by HPLC and UV spectrophotometry, respectively. The results indicated that the developed
analytical method could be employed as an effective technique for the characterization of PMFs.