Optimization of a headspace solid-phase microextraction method for the gas chromatography-mass spectrometry analysis aroma compounds of Litsea mollis Hemsl. immature fruit

Abstract This study optimized using a headspace solid-phase microextraction (HS-SPME) method for extracting volatile aroma compounds, terpenoids in particular, from Litsea mollis Hemsl. immature fruit (LMIF). Gas chromatography-mass spectrometry was used to separate and identify volatile terpenoids in LMIF. The types of SPME fiber coating, salt addition, and desorption time were optimized by single factor-experiments to determine the range of extraction temperature. Built on insights from the single factor-experiments, the response surface methodology was further used to optimize the extraction temperature, extraction time, and equilibrium time of HS-SPME. The results showed that the optimal HS-SPME conditions for extracting volatile terpenoids from LMIF were: 50/30 μm of DVB/CAR/PDMS SPME fiber, 2.0 g of added sodium chloride, desorption at a temperature of 250 °C for 3 min, extraction and equilibrium temperature of 46 °C, extraction time of 36 min, and equilibrium time of 20 min. Under the above conditions, the predicted value of extraction was 66.92, while the experimental value was 65.78. The prediction value matched well with the experimental value with good repeatability. The designed model was proven to be valid, which can be applied for future extraction of aroma compounds from IMIF.

摘要 本研究针对山鸡椒（Litsea mollis Hemsl.）未成熟果实（LMIF）中挥发性香气成分，尤其是萜类化合物的提取，优化了顶空固相微萃取（headspace solid-phase microextraction, HS-SPME）方法。采用气相色谱-质谱联用法对LMIF中的挥发性萜类物质进行分离与鉴定。通过单因素试验对SPME纤维涂层类型、盐添加量及解吸时间进行优化，确定萃取温度的取值范围。在此基础上，进一步采用响应面法对HS-SPME的萃取温度、萃取时间及平衡时间进行优化。结果表明，从LMIF中提取挥发性萜类的最优HS-SPME条件为：采用50/30 μm DVB/CAR/PDMS固相微萃取纤维，添加2.0 g氯化钠，于250 ℃下解吸3 min，萃取与平衡温度为46 ℃，萃取时间36 min，平衡时间20 min。在上述条件下，提取量预测值为66.92，实测值为65.78，预测值与实测值契合度良好，且重复性优异。本研究所构建的模型验证有效，可应用于后续山鸡椒未成熟果实香气成分的提取工作。