Effect of ethoxylated sorbitan ester surfactants on the chromatographic efficiency of poly(ethylene glycol)-based monoliths

The effect of adding ethoxylated sorbitan ester surfactants (Tweens (R)) to poly(ethylene glycol) diacrylate-based monolithic recipes was investigated. Five different Tweens (R) have been evaluated to investigate the exact role of non-ionic surfactants in poly(ethylene glycol) diacrylate-based monolith preparations. These monoliths were characterized by scanning electron microscopy, infrared spectroscopy, and nitrogen physisorption analysis. Different morphological features, and surface areas were observed when different types of Tween (R) were included in the recipe; Tween (R) 20 and 85 showed small globules, while Tween (R) 40, 60 and 80 exhibited larger globular structures with different sizes and degrees of coalescence. The different Tween (R)-based monoliths were investigated for the chromatographic separation of mixtures consisting of hydroxybenzoic acids and alkylbenzenes. These columns were mechanically stable, except for Tween (R) 80. The highest methylene selectivity and the best overall performance were achieved by Tween (R) 60. The efficiency was increased by increasing the concentration of the Tween (R) 60 and the amount of poly(ethylene glycol) diacrylate M-n 700 in the recipes up to 30 wt%, each. Further increases in either Tween (R) 60 or poly(ethylene glycol) diacrylate M-n 700 led to formation of non-permeable columns. The optimized column was successfully used for separation of mixtures of nonsteroidal anti-inflammatory and sulfa drugs, with a maximum efficiency of 60,000 plates/m. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

The study investigated the effect of adding ethoxylated sorbitan ester surfactants (Tweens (R)) to poly(ethylene glycol) diacrylate-based monolithic recipes, characterizing the monoliths through scanning electron microscopy, infrared spectroscopy, and nitrogen physisorption analysis. Different types of Tween (R) resulted in different morphological features and surface areas. The optimized column was successfully used for separating mixtures with a maximum efficiency of 60,000 plates/m.