A targeted metabolomics method for quantification in a single run of multiple classes of phenolics in fruit

In recent years, the interest in phenolic compounds has been increasing due to compelling evidences of their beneficial health properties and to their impact on food quality. The complexity and remarkable diversity of phenolics has challenged the analytical performances of separation and detection methods in terms of resolving power, selectivity and sensitivity for the identification and quantification of these compounds in different matrices. Targeted metabolomics is a strategy based on the use of predefined metabolite-specific signals, such as MRM transitions, that can be used to accurately determine the concentrations of a wide range of known metabolites. We developed a rapid and versatile UPLC-MS/MS based method for the quantification of >150 phenolics, such as benzoates, phenylpropanoids, coumarins, stilbenes, dihydrochalcones and flavonoids in fruits. Compounds commonly occurring in plants were included in the method together with metabolites specific of a single species or family. Reverse-phase chromatography was optimised to achieve separation of the compounds over 15 min, reducing possible ion suppression effects and resolving many isomeric compounds. The optimal fragmentation conditions for each analyte were studied and MRM transitions were selected for accurate quantification. The effectiveness of the method was validated by studying the limits of detection and quantification, the linearity ranges of the instrumental response and the repeatability of the analysis. The method was successfully applied and validated for the analysis of grapes, apples and berries and was shown to represent a valuable tool for the quantitative evaluation of the chemical phenotype, measuring the presence, amount and natural variance in phenolics composition of these fruits.