The Py Solvent Polarity Scale: Binary Solvent Mixtures Used in Reversed-Phase Liquid Chromatography

Abstract

Py values are reported for binary mixtures of tetrahydrofuran - water, acetonitrile - water, methanol - water, tetrahydrofuran - methanol, tetrahydrofuran - acetonitrile, dimethyl sulfoxide - water and dimethylformamide - water, covering the entire range of composition. Interesting features in the variation of Py with solvent composition include: 1) a substantial decrease in Py when small quantities of THF are added to water, 2) a maximum Py value for the methanol - THF system, 3) both maximum and minimum Py values for the water - DMF system, and 4) linearity (or near-linearity) between Py and solvent composition for binary acetonitrile - THF and methanol - water mixtures.