Construction of polymer monolithic columns in polypropylene ink‐pen tubes for separation of proteins by cation‐exchange chromatography

Abstract

We describe the synthesis of polymer monoliths inside polypropylene tubes from ink pens. These tubes are cheap, chemically stable, and resistant to pressure. UV-initiated grafting with 5 wt% benzophenone in methanol for 20 min activated the internal surface, thus enabling the covalent binding of ethylene glycol dimethacrylate, also via photografting. The pendant vinyl groups attached a poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) monolith prepared via photopolymerization. These tubes measured 100-110 mm long, with 2 mm of internal diameter. The parent monoliths were functionalized with Na 2 SO 3 or iminodiacetate to produce strong and weak cation exchangers, respectively. The columns exhibited permeabilities varying from 2.7 to 3.3 × 10 −13 m 2 , which enabled the separation of proteins at 500 µL/min and back pressures <2.8 MPa. Neither structure collapse nor monolith detachment occurred at flow rates as high as 2.0 mL/min, which produced back pressures between 6.9 and 9.0 MPa. The retention times of ovalbumin, ribonuclease A, cytochrome C, and lysozyme in salt gradient at pH 7.0 followed the order of increasing isoelectric points, confirming the cation exchange mechanism. Separation and determination of lysozyme in egg white proved the applicability of the columns to the analysis of complex samples.

Recent developments and applications of polymer monolithic stationary phases

“…The column designed for the reversed‐phase separation was stable even at pressures of 70 bar and successfully applied for the analysis of mixtures of intact proteins. In a recent study, do Nascimento described the synthesis of (glycidyl methacrylate‐ co ‐ethylene glycol dimethacrylate) monoliths in situ in polypropylene ink‐pen tubes 30 . The parent monolith was subsequently functionalized with Na 2 SO 3 or iminodiacetate to produce strong and weak cation exchangers, respectively.…”

“…In a recent study, do Nascimento described the synthesis of (glycidyl methacrylate‐ co ‐ethylene glycol dimethacrylate) monoliths in situ in polypropylene ink‐pen tubes. 30 The parent monolith was subsequently functionalized with Na 2 SO 3 or iminodiacetate to produce strong and weak cation exchangers, respectively. A similar two‐step approach was successfully applied in poly(ethylene‐ co ‐tetrafluoroethylene) tubes by the group of Herrero‐Martinez.…”

Preparation of composite monoliths of quaternized chitosan and diatom earth for protein separation

“…Recently, monolithic adsorption materials have attracted considerable attention in the field of separation technologies as well as that of membrane-type adsorbers [1-3]; their interconnected pores reduce both the diffusion path length of the adsorbate molecules and flow resistance compared to those in packed columns of adsorbent particles [4][5][6][7]. Monolith columns are employed not only in analytical applications but also in preparative separations [8][9][10][11][12].…”