Department of Analytical Chemistry, Faculty of Sciences, University of Extremadura, Avda. de Elvas S/N, 06006 Badajoz, Spain.
Technological Institute of Food and Agriculture (CICYTEX-INTAEX), Junta of Extremadura, Avda. Adolfo Suárez S/N, 06007 Badajoz, Spain.
Talanta. 2019 Jul 1;199:652-661. doi: 10.1016/j.talanta.2019.03.002. Epub 2019 Mar 2.
The applicability of front-face excitation-emission fluorescence spectroscopy to compare grape water extracts of two consecutive sampling dates, corresponding with two maturation stages, and subjected to full irrigation and non-irrigation, was carried out. The decomposition of the obtained three way grape samples was initially analyzed by means of parallel factor analysis (PARAFAC). A tentative identification of fluorophores was done by matching PARAFAC score values with HPLC measurements. It was found that the first PARAFAC component was highly correlated with the sum of concentrations of catechin and epicatechin. The decomposition of the three way fluorescence data by linear discriminant analysis (LDA)-PARAFAC and LDA-unfolding partial least squares (U-PLS) allowed to discriminate between the first and the second maturation stage. The incorporation of an additional mode to the data, achieved by a diethyl ether extraction, giving rise to a four-way excitation-emission-solvent-samples data set, allowed to differentiate between irrigated and non-irrigated samples with the same assayed algorithms. As far as we know, the use of four-way data arrays for classification issues has been reported for the first time.
采用前向激发-发射荧光光谱法对两个连续采样日期（对应两个成熟阶段）的葡萄水提取物进行了比较，这些葡萄水提取物分别经过充分灌溉和非灌溉处理。首先通过平行因子分析（PARAFAC）对获得的三种葡萄样品进行了分解。通过将 PARAFAC 得分值与 HPLC 测量值相匹配，对荧光团进行了初步鉴定。结果发现，第一个 PARAFAC 分量与儿茶素和表儿茶素浓度之和高度相关。通过线性判别分析（LDA）-PARAFAC 和 LDA-非展开部分最小二乘法（U-PLS）对三向荧光数据进行分解，可以区分第一和第二成熟阶段。通过加入二乙醚萃取，将数据扩展到四向激发-发射-溶剂-样品数据集，使用相同的分析算法可以区分灌溉和非灌溉样品。据我们所知，首次报道了使用四向数据阵列进行分类问题的情况。
