Challenges in polymer analysis by liquid chromatography

Synthetic polymers are very important in our daily life. Many valuable properties of polymers are determined by their molecular weight and chemical composition. Liquid chromatographic (LC) techniques are very commonly used for molecular characterisation of polymers. LC analysis of macromolecules is more challenging than analysis of low-molecular-weight compounds, because of polymer dispersity, chemical heterogeneity (several polymer distributions within one sample), poor solubility of many engineering plastics in common chromatographic solvents, and other factors. The present review focuses on difficulties associated with LC analysis of synthetic polymers. The approaches that allow bringing poorly soluble polymers within the scope of LC are discussed. Different LC modes used for polymer separations are reviewed and associated practical challenges are identified. Aspects of optimization of separations in terms of resolution (retention factors, selectivity and efficiency) and analysis time are discussed. Modern technologies (core-shell stationary phases, monolithic columns, and sub-2 mm particles) that may positively affect the trade-off between speed of analysis and efficiency are considered in this respect. Finally, the issue of detection in LC of polymers is addressed. The advantages and limitations of different detection techniques as well as hyphenated techniques are discussed.