Comment on the "Eco-friendly and efficient extraction of polyphenols from Ligustrum robustum by deep eutectic solvent assisted ultrasound".

Qin et al. have proposed an ecological and efficient method of extraction polyphenols from the leaves of Ligustrum robustum using eutectic solvents, assisted by ultrasounds. The authors tested a number of solvents, optimized the extraction parameters and explored the extraction mechanism. According to the results of biological activity experiments of the prepared Ligustrum robustum leaves extracts, they seem promising for practical applications. The issue which is disputable is the identification of the phenolic compounds by using electrospray ionization mass spectrometry, as described in details in this comment.
Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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