Chemometrics Analysis of the Components of Artemisia dracunculus L. Essential Oil with Growth Time

To explore the differences in the quality of Artemisia dracunculus L essential oil at different growth times, gas chromatography-mass spectrometry (GC-MS) was used to analyze the chemical components of Artemisia annua essential oil. The influence of growth time on its chemical composition and relative content was verified through orthogonal partial least squares discriminant analysis (OPLS-DA) and polymer thermal map analysis. The GC-MS analysis results showed that there were a total of 25 substances at each growth time, including 13 terpenes, 9 alcohols, and 3 other substances. In addition, esters, fatty acids, and ketones were also detected at individual growth times. Cluster heatmap analysis showed that most substances had higher content in S1 and S2, followed by S3 and S4, and S5 and S6 had the lowest content. The overall trend of terpenes was that they first decreased, followed by increasing, and then decreased. The total relative content of terpenes was relatively high in April, followed by May, and the lowest of that was in June. The content of alcohol substances was relatively higher before S4 at various growth times, but decreased after S4. At the same time, the content of α-tocopherol was also higher before S4, and Variable Importance for the Projection (VIP) analysis showed that there were a total of 5 substances with VIP greater than 1, namely oleiferin α- Pinene, 3-Carene γ-Sitosterol β-Sitosterol, respectively. Therefore, havesting Artemisia annua and extracting essential oil before late May cauld yield Artemisia annua essential oil of relatively better quality.