近红外光谱检测烟叶化学成分的整叶采样方式研究

为了解决近红外漫反射光谱分析技术用于烟叶整叶检测时，由于烟叶叶面积大、化学成分分布不均，光谱采集代表性和重复性无法保证的问题，对烟叶整叶采样方式进行了系统研究。首先通过信息散度与梯度角正切相结合的光谱相似性方法（SID-GA）计算了7种整叶采样方式获得光谱的相似程度，并采用排序差异和值方法（SRD）对不同采样方式下烟叶总糖、还原糖、烟碱、总氮、钾和氯的偏最小二乘（PLS）定量模型进行了评估。结果表明，B2F、C3F、X2F烟叶样本的最适宜采样方式分别为“8点法”、“6点法”和“8点法”，综合考虑采样点数与模型预测性能，“8点法”被认为是烟叶的最佳光谱采集方式，“6点法”次之。采样点数少、代表性高、重复性好的烟叶整叶近红外光谱采样方式，对提高烟叶品质现场快速分析效率和准确性具有现实意义。

Study on Spectral Acquisition Modes in Determining Chemical Components of Intact Tobacco Leaf by NIRS

When the near-infrared diffuse reflection spectroscopy is used in detecting the quality of intact tobacco leaves, there is no guarantee of spectral representativeness and repeatability because of the large area of a tobacco leaf and the inhomogeneous distribution of chemical compositions in it. In order to solve this problem, a systematic study of sampling modes for intact tobacco leaf had been carried out. The spectral information divergence combined with gradient angle method (SID-GA) was applied to calculate the intact leaf spectrum similarity of seven sampling modes and the sum of ranking differences (SRD) was employed to evaluate the partial least squares (PLS) quantitative models of total sugar, reducing sugar, nicotine, total nitrogen, potassium and chlorine. The results showed that the most suitable sampling modes were "8-point mode", "6-point mode" and "8-point mode" for B2F, C3F and X2F tobacco leaves, respectively. Taking the number of spectral scanning points and performance of PLS models into account, the "8-point mode" can be deemed the most suitable for spectral collection of intact leaf and "6-point mode" takes the second place. It can be concluded that the selected sampling mode with fewer points, higher representative and better repeatability for intact leaf has practical significance for improving predicting efficiency and accuracy of tobacco quality.