Abstract:

On the basis of previous experiments and research projects， this study developed an undergraduate instrumental analysis experiment by expanding the functionality of existing instruments. The primary objective was to enhance awareness among both instructors and students regarding the importance of sample pretreatment. Using Chrysanthemum as the analytical sample， an analytical method for determining the content of camphor and borneol was established based on multiple headspace extraction-gas chromatography-mass spectrometry （MHE-GC-MS）. By systematically optimizing key parameters such as headspace equilibration temperature and time， the optimal pretreatment conditions were determined as an equilibration temperature of 100 ℃ and an equilibration time of 20 min. Method validation demonstrated that both the liquid and solid external standard methods exhibit good linear relationships， correlation coefficients （R²） ranging from 0.981 2 to 0.999 2. Using the established method， the measured contents of camphor and borneol in Chrysanthemum were 0.917 4 mg/g and 0.944 2 mg/g， respectively. These results are significantly higher than those obtained by traditional hydrodistillation-solvent extraction， reflecting the near-complete extraction advantage of MHE. As a comprehensive inquiry-based teaching project， this experiment has been successfully integrated into the instrumental analysis laboratory course， effectively cultivating students’ comprehensive practical skills and scientific thinking in method development， condition optimization， and data processing. The proposed teaching method does not require additional experimental reagents and demonstrates good universality， extendibility， and promotability， providing valuable insights for the reform of instrumental analysis laboratory teaching.

Key words: multiple headspace extraction （MHE）, gas chromatography-mass spectrometry （GC-MS）, camphor, borneol, Chrysanthemum, experimental teaching