## 1 Introduction  
Ginseng, a perennial herb of the Acanthopanax family, is known as the king of herbs and also the king of medicine, and has been used clinically for thousands of years in Asian countries. It is called \"Ginseng\" because its rhizome looks like a person [1]. According to the different growth environments and diverse cultivation modes, ginseng is mainly divided into three categories: Mountain-Cultivated Ginseng (MCG), Garden-Cultivated Ginseng (GCG), and Wild Ginseng (WG). MCG is planted artificially in mountain forests and growsnaturally, GCG is planted artificially in farmland, while WG grows naturally in mountains and forests [2]. Different growth environments lead to the different appearance of ginseng, but it is extremely difficult to distinguish them when the ginseng samples are cut into slices or ground into powder [3]. Due to the high price and low output of WG, the market is dominated by MCG and GCG. The price of MCG is generally higher than that of GCG, so adulteration or falsification has always been widespread in the market. In addition, the different growth environment leads to the diversity of secondary metabolites, which results in different pharmacological activities and clinical values [4; 5]. Thus, the differentiation of MCG and GCG is essential for the effectiveness, safety, and quality stability of ginseng.  
The secondary metabolites are affected by species, growth environment and harvest time, but are not dependent on the external shape of the herbs. Therefore, sophisticated analytical techniques for the chemical phenotype are crucial for chemical composition detection. In recent years, with the development of analytical technology, ultra-high performance liquid chromatography (UHPLC) combined with mass spectrometry (MS), which has the characteristics of high sensitivity, high resolution and high precision mass measurement, has been extensively developed to discriminate ginseng based on the variety of ginsenosides [6; 7; 8; 9]. Compared with UPLC-MS, gas chromatography-mass spectrometry (GC-MS) has a simpler sample pretreatment process and integrates sampling, concentration, and injection together, which is cost-effective and labor saving. Ginseng has its own special odor, and its aroma characteristics has attracted wide attention for ginseng identification, so GC-MS is also applied to discriminate ginseng from different habitats [10] in order to differentiate metabolites in the leaf, stem, petiole, lateral root and main root of ginseng [11], to distinguish the geographical origin of American ginseng [12], to analyze metabolic differences of ginseng berries according to cultivation age and ripening stage [13], to discriminate the three Panax species [14], and to assay the profiling in _Panax ginseng_ and _Panax quinquefolus_[15].  
However, GC-MS coupled with chemometrics has not been applied to systematically investigate the difference between MCG and GCG with different growth years. Therefore, in the present study, a headspace solid-phase microextraction gas chromatography mass spectrometry (HS-SPME-GC-MS) coupled with chemometrics approach was developed to discriminate the volatile component profiles in MCG\({}_{5\text{-}10\text{-}15\text{-}years}\) and GCG\({}_{5\text{-}10\text{-}15\text{-}years}\), and subsequently to discover differentiating chemical markers. Our study not only could systematically characterize the volatile components in ginseng, but could also provide a reliable, accurate method for distinguishing MCG and GCG samples with different growth years.