薰衣草精油微胶囊释放过程的红外光谱研究

Study on the Release Process for Lavender Essential Oil Microcapsule by FTIR

为了解薰衣草精油β-环糊精包合物的构成形式和精油随温度变化的缓释过程,利用傅里叶变换红外变换光谱(FTIR)技术,对薰衣草精油(LO)、β-环糊精(β-CD)及薰衣草精油微胶囊(LOM)进行红外光谱对比分析,同时对不同温度下精油缓释过程中微胶囊红外光谱变化进行了分析,并结合主成分分析,进一步探究β-CD包埋LO后物理化学稳定性及LO释放过程。结果表明,LO包埋后其特征峰有红移现象、峰形变宽,这主要受形成分子间氢键、p-π共轭现象和β-CD空间结构影响;另外,设定温度变化范围25~95℃,温度间隔10℃,测定LOM的红外光谱,以考证β-CD包埋LO的物理化学稳定性及释放情况,分析实验结果表明,LOM中水合物分子较易失去,LOM中的精油组分物理化学性质稳定,在95℃时逸出量小于6.5%,释放缓慢;对变温红外光谱数据进行主成分分析(PCA),前二个主成分的累积方差为99.3%,通过主成分载荷分析,PC1成分可认为是β-CD特征变量,PC2成分为LO特征变量,主成分结果表明,LOM包埋精油中酯类物质的释放速度要快于醇类物质。采用红外分析方法简便快捷,全面了解包埋精油的物理化学稳定性和释放过程,为薰衣草精油微胶囊释放过程的研究提供新的理论支持。

In order to find out the constitute forms of lavenderessential oil-β-cyclodextrin inclusion complex and the process of release of lavenderessential oilwith temperature changes,we used Fourier transform infrared spectroscopy（FTIR）method to compare and analyze lavender essential oil（LO）,β-cyclodextrin（β-CD）and lavender essential oil microcapsule（LOM）,while the infrared spectral changes of release process at different temperatures of the oil in microcapsulewas analyzed,andthe principal component method was further used to explore the physical and chemical stability and release process of LO after it was entrapped byβ-CD.The results showed that comparative analysis by infrared spectroscopy,characteristic peaks of LO embedded had redshift peak and its peak shape became wider,which mainly affected by the formation of molecular hydrogen bonds,p-πconjugate phenomenon and the spatial structure ofβ-CD;in addition,we set temperature range from 25 to 95 ℃,the temperature interval of 10 ℃,and then determined LOM by IR spectrum to test and verify physical and chemical stability and release conditions of LO which was embedded byβ-CD.The results demonstrated that,water molecule inLOM hydrate was easily lost and the essential oil component of LOM was in stable physical and chemical properties,and the amount of escaping for LO at 95℃ was less than 6.5percent when the release was slow;through IR spectra data of variable temperature was analyzed under principal component analysis（PCA）,We may find that the cumulative variance of the first two principal components was99.3%.And PC1 ingredient could be considered as the characteristic variable ofβ-CD and PC2 component was the characteristic variable of LO by principal component load analysis.The result showed that the release of ester from LOM was faster than alcohol.It was simple and efficient by using infrared analysis method to have a comprehensive understanding on the physical and chemical stability and the release process of the embedded oil,and it will provide a new theoretical support for the study on the release process of lavender essential oil microcapsule.