Analysis of chemical composition of nectars and honeys from Citrus by extractive electrospray ionization high resolution mass spectrometry

Analyzing the chemical composition of nectar and honey will contribute to honey traceability, which has become a research hotspot in recent years. However, the rapid, green, and facile analytical methods without tedious chemical pretreatment remain to be developed. Herein, the extractive electrospray ionization high resolution-mass spectrometry (EESI-HRMS) was used to analyze the polyphenols and amino acids composition of the nectars and honeys from three Citrus species, and high-performance liquid chromatography coupled to ultra-violet detector (HPLC-UV) was used to validate the results. 12 polyphenols and 8 amino acids were identified by EESI-HRMS, whilst 9 polyphenols were quantified by HPLC-UV. Principal component analysis (PCA) revealed that the chemical composition of Citrus nectars was similar, and so do honeys, but the nectar and its corresponding honey were chemically differentiated. Accordingly, EESI-HRMS is a reliable analytical method for the analysis of samples with limited sources and complex composition, which contributes to the honey traceability.