化学学报 ›› 2016, Vol. 74 ›› Issue (2): 172-178.DOI: 10.6023/A15100664 上一篇    下一篇

研究论文

直链烷烃近红外光谱的温度效应与应用研究

祁丽华, 蔡文生, 邵学广   

  1. 南开大学化学学院分析科学研究中心 天津市生物传感与分子识别重点实验室 药物化学生物学国家重点实验室天津化学化工协同创新中心 天津 300071
  • 投稿日期:2015-10-17 发布日期:2015-12-23
  • 通讯作者: 邵学广 E-mail:xshao@nankai.edu.cn
  • 基金资助:

    项目受国家自然科学基金(No.21475068)和教育部创新团队(IRT13022)资助.

Effect of Temperature on Near-infrared Spectra of n-Alkanes

Qi Lihua, Cai Wensheng, Shao Xueguang   

  1. Research Center for Analytical Sciences, College of Chemistry, Nankai University, Tianjin Key Laboratory of Biosensing and Molecular Recognition, State Key Laboratory of Medicinal Chemical Biology, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300071, China
  • Received:2015-10-17 Published:2015-12-23
  • Supported by:

    Project supported by the National Natural Science Foundation of China (No. 21475068) and MOE Innovation Team (IRT13022).

近红外光谱的温度效应已得到关注,在结构分析和定量分析方面得到了尝试.以直链烷烃为例,对烷烃有机体系近红外光谱的温度效应进行了研究.采集了20~60℃范围内五种直链烷烃(正己烷到正癸烷)及其混合物的近红外光谱并进行了对比分析,仅发现某些谱峰的强度随温度发生微小变化.采用交替三线性分解算法对光谱数据进行了解析,考察了光谱的特征以及随温度和结构的变化.结果表明,链端C2H5和链中CH2基团的光谱受温度的影响不同,但其光谱信号的强度与温度之间都具有良好的线性关系,可根据光谱预测体系的温度;两种基团的光谱信号强度与烷烃分子的碳数或两种基团在分子中相对含量都具有良好的线性关系,可用于直链烷烃混合物组成的估算.

关键词: 近红外光谱, 温度效应, 直链烷烃, 交替三线性分解, 定量光谱温度关系(QSTR)

Effect of temperature on near-infrared (NIR) spectra has been studied and applied to structural and quantitative analyses. To investigate the effect of temperature on NIR spectra of alkyl organic system, n-alkanes were studied in this work. NIR spectra of pure n-alkanes (hexane to decane), binary (hexane and octane) and ternary (octane, nonane and decane) mixtures were measured. In the experiments, temperature was controlled to change from 60 to 20℃ with a step of ca. 5℃. Comparing the spectra at different temperatures, only a little difference in peak intensity of some bands can be found. Therefore, alternating trilinear decomposition (ATLD) algorithm was adopted to analyze the three-order data matrix. The results show that two spectral loadings are obtained because the influence of temperature on the spectra of terminal ethyl (C2H5) groups differs from that of mid-chain methylene (CH2) groups. Furthermore, the temperature scores of CH2 and C2H5 groups decrease linearly with temperature, implying that the temperature effect can be quantitatively described by a quantitative spectra-temperature relationship (QSTR) model. The QSTR model provides an efficient way to predict the temperature of n-alkane solutions. Good linearity also exists between sample scores and carbon number or the relative content of CH2 and C2H5 groups in the molecules of the n-alkanes. Linear models between the two scores and the relative content of CH2 and C2H5 groups are obtained, respectively, using the least square fitting of the score and the relative contents. The model can be used for prediction of the relative content of CH2 and C2H5 groups in mixtures, which can further be used to estimate the composition of the mixtures. Furthermore, the relationship between the scores and the carbon atom numbers is modeled using multivariate linear regression (MLR). The composition of n-alkane mixtures can also be estimated through the predicted carbon number using the MLR model. These models are validated by binary and ternary mixtures of the n-alkanes. It was indicated that the relative contents of CH2 and C2H5 groups or the carbon atom number can be predicted using the models. Therefore, a new way for quantitative estimation of the composition in n-alkane mixtures was developed using the temperature effect of the near-infrared spectra.

Key words: near-infrared spectra, temperature effect, n-alkane, alternating trilinear decomposition, quantitative spectratemperature relationship