Holden Carol A, Hunnicutt Sally S, Sánchez-Ponce Raymundo, Craig John M, Rutan Sarah C
Department of Chemistry, Virginia Commonwealth University, PO Box 842006 Richmond, Virginia 23284-2006, USA.
Appl Spectrosc. 2003 May;57(5):483-90. doi: 10.1366/000370203321666470.
The structure of the mobile phase in liquid chromatography plays an important role in the determination of retention behavior on reversed-phase stationary materials. One of the most commonly employed mobile phases is a mixture of methanol and water. In this work, infrared and Raman spectroscopic methods were used to investigate the structure of species formed in methanol/water mixtures. Chemometric methods using multivariate curve resolution by alternating least-squares analysis were used to resolve the overlapped spectra and to determine concentration profiles as a function of composition. The results showed that the structure of these mixtures could be described by a mixture model consisting of four species, namely, methanol, water, and two complexes, methanol/water (1:1) and methanol/water (1:4). The spectral frequencies and concentration profiles found from the Raman and infrared measurements were consistent with one another and with theoretical calculations.
液相色谱中流动相的结构在反相固定材料上保留行为的测定中起着重要作用。最常用的流动相之一是甲醇和水的混合物。在这项工作中，使用红外和拉曼光谱方法研究了甲醇/水混合物中形成的物种结构。采用交替最小二乘法进行多元曲线分辨的化学计量学方法来解析重叠光谱，并确定作为组成函数的浓度分布。结果表明，这些混合物的结构可以用一个由四种物种组成的混合模型来描述，即甲醇、水以及两种配合物，甲醇/水（1:1）和甲醇/水（1:4）。从拉曼和红外测量中得到的光谱频率和浓度分布彼此一致，并且与理论计算结果相符。
