Fluid revisited: An overlook of a method for solubility measurements in supercritical fluids based on chromatography retention

Abstract

Measuring solubility in supercritical fluids usually represents a technical challenge since it is a highly compressible media sensitive to sampling and processing. Several decades ago, a chromatographic method for measuring solubility in supercritical fluids was presented by Bartle et al based on a linear relationship between solubility and inverse retention coefficient in supercritical fluid chromatography. Despite clear advantages such as high productivity and simplicity of sample preparation the method received only a limited acceptance in the field. In this work, the method was re-evaluated using several model compounds and stationary phases in supercritical fluid chromatography in conditions close to the limits of method applicability. Effects of calibration approaches, flowrates, initial calibration data and chromatography sample solvents were tested. The method appeared to be surprisingly robust and reasonably precise even for compounds which do not fully comply with the requirements for method applicability. It could be considered as an express method of choice when large sets of solubility data at different pressures are required.