In this paper,two-dimensional (2D) correlation spectroscopy analysis was applied to investigate the influence of the main comp onent in blood and the systematic drift during the measurement on the specificit y of glucose in the near-infrared (NIR) spectroscopy.First,the NIR transmitta nce of glucose aqueous solutions was measured and the 2D correlation NIR spectra were calculated under the perturbation of glucose concentration.Based on the c omparative analysis for synchronous and asynchronous 2D correlation spectra,the characteristic absorption peaks of glucose in the combination band and the over tone band were determined.Then a small amount of albumin was added into glucose aqueous solutions,and the transmittance was recorded to perform 2D correlation spectroscopy analysis under the perturbation of glucose concentration.However,the absorption of glucose in the first overtone band (1590nm) and second overto ne band (1195nm) was no longer homologous in the 2D correlation spectra,which m eans that the albumin may reduce the specificity of glucose.Further,the oral g lucose tolerance test of healthy volunteer was conducted and the NIR diffuse ref lectance of left palm was collected in vivo.The 2D correlation analysis res ults showed that,the homology of glucose in the diffuse reflectance was also de stroyed.Moreover,as the spectral variation from the glucose concentration chan ge is too low to be covered by that induced by systematic drift easily,some bac kground correction methods were usually required.For the transmittance experime nt of glucose aqueous solutions and the diffuse reflectance experiment of human body,the pure water sample and 5% diffuse reflectance standard were used as the reference,respectively.Then 2D correlation spectroscopy was developed under t he perturbation of measurement time.Results showed that,smaller band shift was observed in the slice spectra of 2D correlation synchronous spectra after the c orresponding background correction,and the specificity of glucose was improved both in the in vitro and in vivo experiments.So for the non-invasive g lucose sensing by NIR spectroscopy,the wavelengths should be chosen carefully t o avoid the absorption band of some interfering components which may destroy the homology of glucose and make spectral interpretation more complicated.And the selection of reference samples for relative measurement is also important to imp rove the specificity of glucose.%主要利用二维相关光谱分析方法考察了血液中主要成分、测量过程中的系统漂移等因素对近红外光谱中的葡萄糖分子特异性的影响.首先测量了葡萄糖水溶液的近红外透射光谱,以葡萄糖浓度为外扰,计算二维相关同步谱及异步谱,通过对比分析确定了葡萄糖在合频和倍频区域的特征吸收峰位置.当葡萄糖水溶液中加入少量白蛋白后,其二维相关谱中葡萄糖的一级倍频吸收峰(1 590 nm)和二级倍频吸收峰(1 195 nm)出现了不同源的现象,表明白蛋白可能破坏了葡萄糖的特异性;进一步开展了人体口服葡萄糖耐量实验,测量了手掌部位的漫反射光谱,其二维相关谱中葡萄糖的同源性吸收也遭到破坏.另外,由于葡萄糖浓度变化引起的光谱变异信息较小,很容易被系统漂移掩盖,一般需要进行背景修正.在葡萄糖水溶液的透射实验和人体漫反射实验中,分别引入纯水样本和5%标准漫反射板作为参考,以时间为扰动的二维相关光谱分析的结果表明,经过参考样本的背景校正后,系统漂移在二维同步切线谱中引起的谱峰偏移变小,葡萄糖的特征吸收被增强.因此,在近红外光谱无创血糖检测中,应尽量避开与葡萄糖特征吸收不同源的波段,并有必要采取一定的参考测量方法以提高检测的特异性.
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