Strategy for optimized use of LC-MSn for determination of the polyphenolic profiles of apple peel, flesh and leaves

Abstract The diversity of polyphenolic compounds implies the need for methods with high selectivity and sensitivity for their identification and quantification in food and biological samples. In this work, the use of ion trap mass spectrometer has been optimized for systematic qualitative and quantitative analysis of the polyphenolic compounds in apple peel, flesh and leaves. For identification, screening was performed consisting of full scan, single ion monitoring and data-dependent scan for the aglycone/glycoside pairs with the expected aglycones as targets. For quantification, the ion trap was optimized by testing sixteen reference polyphenols and a segmented tune MS method was established, where each class of polyphenols was quantified employing an optimized tune in the full scan mode. Using these methods, derivatives of hydroxycinnamic and hydroxybenzoic acid, flavones, flavonols, flavanols, and dihydrochalcones were identified and quantified. The validation of HPLC-HESI (heated electrospray)-MS method showed that the analytical characteristics of the developed MS method are comparable to UV-DAD with regard to recovery, precision and robustness, and superior for its linear range, sensitivity and selectivity that affects in higher results for the polyphenolic compounds measured with MS. The developed and validated method was used for identification and quantification of 27 polyphenolic compounds in apple peel, flesh and leaves of three apple cultivars (Tetovka, Golden delicious and Red delicious from Resen region, Republic of Macedonia) demonstrating its reliability and efficiency for fast screening of polyphenols in apples. Highest content of polyphenols was measured in the Tetovka autochthonous cultivar (17.61 mg/g dried leaves, 19.93 mg/g and 17.28 mg/g lyophilized flesh and peel, respectively) and lower content was found in Red delicious (15.23 mg/g dried leaves, 11.41 mg/g and 18.07 mg/g lyophilized flesh and peel, respectively) and Golden delicious (14.61 mg/g in dried leaves, 16.86 mg/g and 14.01 mg/g in lyophilized flesh and peel, respectively).