Niazi Ali, Rezaei Amir Ahmad, Shahhosseini Fatemeh
Department of Chemistry, Faculty of Sciences, Azad University of Arak, Arak, Iran.
Ann Chim. 2007 Mar-Apr;97(3-4):199-211. doi: 10.1002/adic.200790005.
The acidity constants of Alizarine Red S were determined spectrophotometrically at 25 degrees C and at constant ionic strength 0.1 M (KNO3) in pure water as well as in aqueous media containing variable mole percentages (5-70%) of organic solvents. The organic solvents used were methanol, ethanol, N,N-dimethyl formamide (DMF), dimethyl sulfoxide (DMSO), acetonitrile and dioxan. The acidity constants of all related equilibria are estimated using the whole spectral fitting of the collected data to an established factor analysis model. DATAN program was applied for determining of acidity constants and pure spectra of different form of Alizarine Red S. The obtained results indicated that acidity constants decrease as the content of an organic solvent in the medium increases. There are linear relationship between acidity constants and the mole fraction of various organic solvents in the solvent mixtures. Effect of various solvents on acidity constants and pure spectrum of each component are also discussed.
在25℃以及离子强度恒定为0.1M（硝酸钾）的条件下，采用分光光度法测定了茜素红S在纯水以及含有不同摩尔百分比（5 - 70%）有机溶剂的水性介质中的酸度常数。所使用的有机溶剂有甲醇、乙醇、N，N - 二甲基甲酰胺（DMF）、二甲基亚砜（DMSO）、乙腈和二氧六环。利用收集的数据对已建立的因子分析模型进行全光谱拟合，估算所有相关平衡的酸度常数。应用DATAN程序来测定茜素红S不同形式的酸度常数和纯光谱。所得结果表明，酸度常数随着介质中有机溶剂含量的增加而降低。酸度常数与溶剂混合物中各种有机溶剂的摩尔分数之间存在线性关系。还讨论了各种溶剂对酸度常数和各组分纯光谱的影响。
