Atractylodis rhizoma is from the Composite family, which is the dried roots of A. lancea (Thunb.) DC. and A. chinensis (DC.) Koidz [1]. The former is predominantly distributed in the provinces of Jiangsu, Zhejiang, Anhui, Hubei, and Jiangxi, while the latter is native to Hebei, Heilongjiang, Liaoning, Jilin, and Inner Mongolia. Flora of China also records its other botanical origins including A. japonica Koidz. ex Kitam. and A. coreana (Nakai) Kitam. Atractylodis rhizoma holds a paramount position in traditional therapies within the enduring history of Chinese medicine culture. It is renowned for its crucial effects of addressing dampness, enhancing spleen function, dispelling wind, alleviating cold, and promoting visual acuity. Modern pharmacological research has further demonstrated that atractylodis rhizoma possesses a series of pharmacological effects, including anti-tumor, antimicrobial, anti-inflammatory, immune-modulating, and gastrointestinal function-improving properties [2]. The chemical compositions and pharmacological effects have obvious differences among the different species of atractylodis rhizoma. The similar morphological characteristics increase the difficulty to differentiate between them and cannot be discriminated through the eyes and nose [3], [4]. Up to present, they have not been nicely distinguished in market circulation and clinical application, resulting in the phenomenon of mixed use. Therefore, it is obliged to develop a dependable method for discriminating different species of atractylodis rhizoma for its quality control and resource development.

Atractylodis rhizoma is rich in volatile oils and the commonly used tools for its detection are gas chromatography and mass spectrometry. Chen et al. [5] identified 30 compounds from atractylodis rhizoma using GC-MS. Among them, atractylon, hinesol, β-eudesmol, elemol and atractydin were the main volatile compound. Liu et al. [6] differentiated 41 and 45 components from atractylodes lancea and atractylodes koreana by GC-MS method, respectively. And atractylone was the primary component in atractylodes lancea, while eudesma-4(14)-en-11-ol was the major in atractylodes koreana. However, because of the complexity of the drug composition, rhe sample pretreatment process is cumbersome and time-consuming, which led to the slow detection of samples. HS-SPME-GC-MS is a special gas chromatography-mass spectrometry technology which does not need sample pretreatment, thus avoiding the tedious operation of extracting volatile oil. It is precisely due to this characteristic that HS-SPME-GC-MS has a wide range of applications in the analysis and characterization of VOCs [7], [8], [9]. However, in comparison to GC-MS, HS-SPME-GC-MS eliminates the need for sample pretreatment while still having drawbacks such as prolonged detection time and intricate operation. Therefore, a range of new detection tools for VOCs have also been developed. HS-GC-IMS is a developing gas phase analysis and detection technique with excellent separation ability of GC and high sensitivity of IMS that separates chemical ions based on their migration degree under different electric fields [10]. Due to its operation under atmospheric pressure, it is very suitable for trace detection of some organic compounds for instance drugs [11] and explosives [12]. In recent years, it has extensive applications in various fields such as food [13], [14], traditional Chinese medicine [15], agriculture [16], and environment [17]. HS-GC-IMS usually used for detecting small molecules of VOCs, which can make up for the insufficiency of HS-SPME-GC-MS that only detect medium molecules of VOCs. Hence, the integration of HS-SPME-GC-MS and HS-GC-IMS can offer a more overall characterization of the VOCs in atractylodis rhizoma samples.

Atractylodis rhizoma possess a special odor, which is also an important characteristic of it. Consequently, it is possible to reflect the inherent essence of atractylodis rhizoma by exploring the odor characteristics. Electronic nose (E-nose) has emerged in recent years, which can simulate human sensory systems to analyze and identify the overall information of substances with fragrance contained in samples. Traditional E-nose instruments are composed of multiple metal oxide gas sensors, with each sensor responding to the odor of VOCs. However, the stability of traditional E-nose instruments is poor due to the sensors being prone to drift and contamination [18]. The emergence of ultra-fast GC E-nose has made up for this disadvantage. It has the characteristics of fast detection speed, wide analysis range, low analysis cost and objective detection results, which lead to a wide spread range of applications in various fields such as food [19], medicine [20] and dairy [21].

This study aims to analyze and identify VOCs in different varieties of atractylodis rhizoma using HS-SPME-GC-MS, HS-GC-IMS, and ultra-fast GC E-nose techniques. By integrating these techniques, researchers can obtain detailed information about VOCs in different varieties of atractylodis rhizoma. This multidimensional analysis method can provide comprehensive and accurate results for sample characterization, which helps to better understand the compositional differences and characteristics of volatile compounds in atractylodis rhizoma. The application of this integrated analysis method is novel in the field of atractylodis rhizoma and provides a basis for quality control of atractylodis rhizoma medicinal materials, which have important significance for the development of atractylodis rhizoma medicinal resources.