Abstract

In the development of new commercial products in the pharmaceutical and food industries, acid dissociation constant (K_a) values of active and inactive ingredients are important factors for the estimation of the biological activity. In this regard, new spectrophotometric approaches based on parallel factor analysis (PARAFAC) and multivariate curve resolution-alternating least squares (MCR-ALS) to pH-absorbance dataset are described for the simultaneous determination of the acid dissociation constants of the phenolics ferulic acid, 4-hydroxybenzoic acid, syringic acid, protocatechuic acid, vanillic acid, and isovanillic acid that have more than one dissociation equilibrium without using classical titration procedures. The acid dissociation constants were determined by the pH profiles obtained by bilinear MCR-ALS and trilinear PARAFAC decomposition of pH-ultraviolet and pH-ultraviolet-visible spectroscopic datasets of the phenolics. For the quantification of the acid dissociation constants with the MCR-ALS and PARAFAC approaches, the estimated spectral profiles provided an opportunity for the direct observation of the individual spectral bands of each phenolic without the use of additional software. The results showed that MCR-ALS and PARAFAC applications to spectrophotometric measurements at various pH values were alternatives for solving acid dissociation constant problems that cannot be determined by classical methods.

摘要

在制药和食品工业新商业产品的开发中，酸解离常数 (K _a) 活性和非活性成分的值是估算生物活性的重要因素。在这方面，描述了基于平行因子分析 (PARAFAC) 和多元曲线分辨率交替最小二乘法 (MCR-ALS) 到 pH 吸光度数据集的新分光光度法方法，用于同时测定酚类阿魏酸的酸解离常数， 4-羟基苯甲酸、丁香酸、原儿茶酸、香草酸和异香草酸，无需使用经典滴定程序即可达到一种以上的解离平衡。酸解离常数由双线性 MCR-ALS 和三线性 PARAFAC 分解酚类物质的 pH-紫外线和 pH-紫外线-可见光谱数据集获得的 pH 曲线确定。对于用 MCR-ALS 和 PARAFAC 方法量化酸解离常数，估计的光谱曲线为直接观察每个酚类的各个光谱带提供了机会，而无需使用额外的软件。结果表明，MCR-ALS 和 PARAFAC 应用于各种 pH 值下的分光光度测量是解决传统方法无法确定的酸解离常数问题的替代方法。