Development of Water-Based Liquid Chromatography at the Critical Condition

Liquid chromatography at the critical condition (LCCC) is a chromatographic technique that allows for the isolation of one area of the polymer matrix so that other areas of the polymer may be probed with size-exclusion or adsorptive chromatographic modes. This technique has been successfully applied to the analysis of functionality distributions in functionalized oligomers and to polymer distributions within copolymers. Herein, the critical conditions of two polar polymers, poly(acrylic acid) and polystyrene sulfonate, are determined. These conditions were identified by varying buffer concentration, organic modifier within the mobile phase, or both. At the critical condition of poly(acrylic acid), the retention characteristics of a copolymer of acrylic acid and vinyl pyrrolidinone were determined. This extension to water-based mobile phase conditions will substantially broaden the possible applications of LCCC.