Abstract: In this study, the essential oil content and composition of fingered citrons harvested in Guangdong province in different months of the same year were analyzed by gas chromatography-mass spectrometry (GC-MS) and gas chromatography-ion mobility spectrometry (GC-IMS). The results showed that the essential oil content of fingered citrons peaked in September. GC-MS and GC-IMS identified 54 and 61 volatile components in the essential oil of finger citrons harvested at five different times, respectively, with terpenes being the dominant ones, followed by alcohols, aldehydes and esters. GC-MS indicated that alcohols, aldehydes, esters, alkanes and phenols mainly existed in the samples harvested in August and September at low levels. GC-IMS demonstrated that aldehydes, esters and acid compounds were mainly found in the samples harvested in June, July and August. Two chemometric methods, heat map clustering and principal component analysis, were used to distinguish the essential oils from fingered citrons harvested at five different times. The results of GC-MS and GC-IMS showed differences from each other. Most of the volatile components detected by GC-MS were larger molecules (C9–C21) at high levels, while most of the volatile components detected by GC-IMS were smaller molecules (C2–C10) at low levels. The combined application of both technologies expanded the scope of detectable volatile components in the essential oil from fingered citrons and could provide a scientific basis for the quality identification of the essential oil and the selection of optimal harvest time for fingered citrons.

Key words: gas chromatography-mass spectrometry; gas chromatography-ion mobility spectrometry; volatile compounds; different harvest times; essential oil of fingered citrons from Guangdong province