Novel oil-in-ionic liquid microemulsion extraction and in situ liquid–liquid microextraction of natural phenolic compounds from functional foods

A novel ultrasonic-assisted oil-in-ionic liquid microemulsion extraction and in situ liquid–liquid microextraction method was developed via integrating ultrahigh-performance liquid chromatography and quadrupole time-of-flight mass spectrometry to determine phenolic compounds in functional foods. During experimentation, a series of factors affecting the extraction efficiency were optimized, such as types and contents of microemulsion components, salt amount, pH value of microemulsion, and ultrasonic time. Furthermore, a response surface methodology was applied to optimize the extraction conditions. Under the optimized conditions, the method presented a linear relationship in the range of 0.08–4 μg/mL, with correlation coefficients ranging from 0.9967 to 1.0000. Intraday (n = 6) and interday (n = 6) precision levels of the method were <4.91 %, which was within the acceptable range. The limits of detection and quantification were 2.06–30.77 and 6.86–102.56 ng/mL, respectively. The method was successfully applied to Tetrastigma hemsleyanum to attain a recovery ranging 89.44 %–109.34 %. • A UA-O/IL-MEE and ISLLME is proposed for the extraction of natural compounds. • Combining microemulsion extraction with in situ enrichment enables sensitive detection. • The greenness and practicability of the method are evaluated using AGREE and BAGI. • The developed method is efficient, environmentally friendly, and highly sensitive for functional foods.