## 3 Results and Discussions  
### Optimization of HS-SPME Extraction Conditions  
The selection of fiber coatings is crucial for achieving optimal adsorption efficiency. Prior to analyzing benzenemethanethiol, we optimized parameters to enhance extraction efficacy. The efficiency of solid-phase microextraction (SPME) fibers can vary depending on the coating material used [23; 24]. Several studies have employed various extraction fibers to characterize sulfur-containing compounds in foods and beverages [13; 15; 25; 26; 27]. In this study, we tested four types of SPME fibers (DVB/CAR/PDMS, CAR/PDMS, PDMS, and PA) for their ability to extract benzenemethanethiol from sorghum extract. Fibers with DVB/CAR/PDMS and CAR/PDMS coatings demonstrated superior capacity for extracting benzenemethanethiol compared to the other fibers (Figure 2). Specifically, the response areas for benzenemethanethiol using the CAR/PDMS fiber were significantly better than the other three fibers, with a relative standard deviation (RSD) of less than 10% (\(p<0.05\)). Our findings are consistent with a recent study that used a CAR/PDMS fiber coupled with GC \(\times\) GC-SCD to extract volatile sulfur-containing odorants in Chinese Laobaign baijiu [13]. Therefore, CAR/PDMS was chosen for the next period of HS-SPME optimization in fibers test under equivalent conditions, as it manifested the optimal extraction efficiency and was excellent for extracting benzenemethanethiol from the sorghum extract medium. The optimization of Solid Phase Microextraction (SPME) conditions for extracting benzenemethanethiol were carried out using a single-factor approach, focusing on salt dosage, extraction time and temperature, and desorption time as independent variables. The addition of NaCl was found to have a stimulating effect on the release of volatile compounds in food matrices by increasing the ionic strength of the sample and diminishing the solubility of analytes. This, in turn, increased the distribution of corresponding compounds on the fiber coating and enhanced the adsorption of volatile substances by the extraction fiber. This study investigated the effects of five different levels of salt addition on the extraction performance of benzenemethanethiol. The peak area of benzenemethanethiol demonstrated an initial increase, followed by a decrease, with increasing addition of sodium chloride, reaching the highest level at 3 g/8 mL. Therefore, 3 g/8 mL was selected as the optimal salt dosage for further HS-SPME optimization. The attainment of equilibrium within the system is influenced by an array of factors, encompassing the distribution coefficient of the components, the rate of substance diffusion, the characteristics of the sample matrix, the volume of the sample, and the thickness of the  
Figure 2: Response areas of benzenemethanethiol extracted with different fibers measured in the sorghum extract medium. Values not sharing the same superscript letter (a, b, c, d) on the top bar are different according to Duncan’s test. fiber membrane employed for extraction [28]. Figure 3 demonstrates that the chromatographic peak of benzenemethanethiol exhibited a gradual augmentation as the duration of extraction was prolonged, albeit with a diminishing rate of increase. Moreover, when the extraction time exceeded 30 min, there was no significant difference in the extraction efficiency. Consequently, 30 min was identified as the optimal extraction time. Elevating the temperature during extraction enhanced the distribution coefficient and accelerated analyte mass transfer, ultimately resulting in improved extraction efficiency. Within a temperature range of 25-45 \({}^{\circ}\)C, the amount of extracted benzenemethanethiol exhibited a positive correlation with increasing temperature. However, beyond 30 \({}^{\circ}\)C, no significant difference in extraction efficiency was observed.