HPLC-DAD-ESI-MS2 analysis of phytochemicals from Sichuan red orange peel using ultrasound-assisted extraction

Citrus reticulata 'Blanco' peel is a byproduct of red oranges, which are commonly grown in Sichuan Province, China. An optimized protocol involving ultrasound-assisted extraction (UAE) was developed to extract phytochemicals from the peel for analysis. The parameters of the optimized UAE were as follows: ratio of 85% ethanol to orange peels at 20:1 (ml/g), duration of 40 min, temperature of 50 °C, powder mesh size of 100, and ultrasound power of 150 W. The yields of the two main phytochemicals, namely, tangeretin and nobiletin, extracted using UAE were 1.5 times higher than those obtained using conventional solvent extraction (CSE). HPLC-DAD-ESI-MS2 analysis showed that the efficiency of UAE in recovering tangeretin and nobiletin from red orange peel was higher than that of CSE.