Abstract: This study aimed to establish a method for the determination of polyphenols in Osmanthus fragrans flowers by extractive electrospray ionization-mass spectrometry (EESI-MS). The main polyphenolic compounds in the methanol extract of O. fragrans var. semperflorens flowers were determined by high performance liquid chromatography (HPLC) and EESI-MS. The results showed that the contents of total phenols and total flavonoids in the methanol extract were (133.38 ± 0.12) and (72.49 ± 0.09) mg/g, respectively. Fifteen polyphenolic compounds were detected by HPLC, with myricetin, morin, rutin, naringenin and (+)-catechin being abundant. p-Protocatechuic acid, coumaric acid, caffeic acid, and epicatechin were detected by EESI-MS in the negative ion mode while cinnamic acid, morin and myricetin were detected in the positive ion mode. The EESI-MS method in this study had the advantages of low sample consumption, no complex pretreatment and short analysis time and could be used for the analysis of polyphenols in food samples.

Key words: extractive electrospray ionization-mass spectrometry, total phenols, total flavonoids, polyphenol, Osmanthus fragrans