Isolation and identification of phenolic compounds in Citrus sinensis

Various methods were compared for the recovery of phenolic compounds from sweet orange. The need for careful consideration of sample preparation was demonstrated. In the case of cinnamic acids, hydroxide-treatment was essential to liberate the bound acids. Ferulic acid was the predominant phenol in alkali-treated extracts. Positive and negative ion electrospray ionisation mass spectra were systematically investigated for a range of phenols. Detection limits were significantly lower in negative ion than in positive ion mode. However, positive ion mode provided additional structural information for many of the compounds. (C) 2000 Elsevier Science B.V. All rights reserved.