## 1 Introduction  
Chlorobenzenes (CBs) are a kind of raw materials for the synthesis of pesticides, dyes, chemical agents, polymers, and other fine chemicals, and have been widely used in modern industries. However, CBs would also endanger human health due to their refractory degradation, high toxicity, fat solubility, and bioaccumulation. CBs are very irritating to the eyes and skin, and can even inhibit the human nerve center and damage the liver and kidneys if water contaminated with CBs is ingested [1, 2]. Therefore, CBs have been listed as priority pollutants by many governments all over the world. In view of this, it is essential to develop a simple and sensitive analytical method for monitoring the contamination of CBs in water. Generally, traditional approaches for the determination of CBs in water have been established by using gas chromatography (GC) or gas chromatography-mass spectrometry (GC-MS) after pretreatment procedures such as liquid extraction and solid-phase extraction [3]. It is well known that the sample pretreatment consumes most of the time and labor during an analytical process. In comparison to traditional pretreatment techniques,solid-phase microextraction (SPME) presented outstanding performances for the extraction of organic compounds from water, owing to its advantages of solvent-free sampling, straightforward operation, and the integration of sampling, extraction, and injection into a single step [4; 5]. The extraction capacity for analytes depends on the adsorption performance of coating materials; therefore, SPME coatings play an important role in the sensitive extraction of targeted analytes [6; 7]. Although various commercial SPME coatings have been developed, a great effort should be made to further improve the extraction capacity for determining trace analytes. Up to now, a variety of materials have been investigated as SPME coatings, such as carbon-based materials, metal oxides, metal-organic frameworks, covalent organic frameworks, and polymers, etc. [8; 9; 10], wherein carbon-based materials displayed glorious extraction performance towards non-polar and slightly polar compounds because of their hydrophobicity and ease of functionalization [11; 12; 13]. As a type of zero-dimensional carbon-based material, carbon dots (CDs) have been widely used in various fields, such as chemical sensing, biosensing, drug delivery, catalysis, etc. [14; 15; 16; 17], given that CDs possess abundant oxygen-containing groups on the surface, e.g., hydroxyl and carboxyl groups, which provide plentiful active sites for adsorbing targeted compounds through electrostatic attraction, hydrogen bonding, and \(\pi\)-\(\pi\) interactions [18]. However, the application of CDs for extracting targeted compounds from aqueous samples was limited by the isolating difficulty of CDs after adsorption due to their strong hydrophily. Therefore, a supported material can be used for the immobilization of CDs to overcome this drawback [19]. [PERSON] et al. [20] synthesized carbon dot@poly(glycidyl methacrylate) (PGMA)@Fe\({}_{3}\)O\({}_{4}\) nanoparticles as an adsorbent for the solid-phase extraction of polycyclic aromatic hydrocarbons from water samples. The extraction performance was tunable through controlling the doped amounts of CDs and changing the polymer length. [PERSON]'s group prepared CDs and polyethyleneimine-functionalized CD-decorated silica microparticles as a stationary phase of liquid chromatography [21; 22]. Results showed that the decorated CDs enhanced the separation capacities for nucleosides and sulfonamides effectively. Although the adsorption performance of CDs has been investigated by modifications to support materials, alternative supports should be explored for expanding the application of CDs. Furthermore, there are few reports on the research of CDs in SPME.