A Rayleigh light scattering study on mixing states of 2-propanol–water binary mixtures widely used as mobile phase in separation

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• 作者：Wu ; Ying Guang ; Tabata ; Masaaki ; Takamuku ; Toshiyuki
• 关键词：Rayleigh light scattering ; Concentration fluctuation ; Kirkwood&ndash ; Buff parameters ; Microheterogeneity ; Water&ndash ; organic mixed solvent ; 2-Propanol
• 刊名：Talanta
• 出版年：2001
• 出版时间：March 30, 2001
• 年：2001
• 卷：54
• 期：1
• 页码：69-77
• 全文大小：156 K

文摘

Rayleigh light scatterings of 2-propanol–water binary mixtures at 546 nm have been measured by using a conventional fluorophotometer at 25°C. Mean square concentration fluctuations and Kirkwood–Buff parameters of the mixtures in a range of 2-propanol mole fraction of 0.0≤x_2pr≤0.4 (0–75 % (v/v)) have been calculated from the scattering intensities. On the basis of these parameters, it has been concluded that at x_2pr<0.05 (15 % (v/v)) 2-propanol is well solvated by water molecules, and hydrates consisting of one 2-propanol molecule and 20–30 water molecules are formed in the mixtures. However, at 0.05≤x_2pr≤0.3 (15–65 % (v/v)) large clusters mainly composed of 2-propanol molecules are formed in the mixtures, and these clusters are further reduced into small 2-propanol aggregates at x_2pr≥0.4. The usage of 2-propanol as organic modifier and its effects on CE and RPLC separations are also discussed in terms of microheterogeneity in the mobile phase.