近红外光谱无创生化检测中不定光程对模型精度的影响研究

利用近红外血流容积光谱相减方法无创伤定量分析人体血液生化成分时,获得的在体血液光谱对应的样品光程是不确定的。为研究样品间的光程差异对定标模型预测精度的影响,配制了30份模拟血清样品,利用可变光程样品池,采用傅里叶光谱仪分别测量了相同光程和不定光程两组样品的近红外光谱。以分析血清白蛋白成分为例,对两组样品的定标模型精度进行比较,结果显示不定光程组的模型精度与相同光程组的模型精度相比明显下降,交叉检验标准差(RMSECV)由110.0mg/dL增大至156.0mg/dL。采用多元散射校正算法对上述光谱数据校正后,RMSECV降低至98.1mg/dL。对比分析处理前后两组模型的精度,证实了采用适当的预处理方法能够有效校正不定光程引起的光谱误差,提高模型预测精度。

Effect of Variable Optical Path Length on the Accuracy of the Model in Noninvasive Biochemical Detection by NIR Spectrum

For noninvasive quantitative analysis of blood biochemical components, near infrared (NIR) subtracted blood volume spectrometry is applied. However, the optical path lengths corresponding to in vivo blood spectra obtained are uncertain. In order to study the effect of optical path length difference on the prediction accuracy of calibration model, 30 serum samples are simulated. A variable path-length cell is used to produce optical path difference, and spectra of two sample sets, with equal and different path-lengths respectively, are measured by Nicolet 6700 Fourier transform infrared (FT-IR) spectrometer. As to serum albumin, the calibration accuracies of the two groups are compared. The results show that the samples with uncertain optical path would reduce the calibration accuracy, as the root mean square error of cross validation (RMSECV) of the model increases from 110.0 mg/dL to 156.0 mg/dL. By applying multiplicative scatter correction, RMSECV of the uncertain optical path set reduces to 98.1 mg/L. It indicates that appropriate pretreatment method can effectively correct the error of spectrum caused by uncertain optical path length, thus improve the accuracy of the prediction model.