No abstract

We demonstrated that the porous structure and the reactivity of the epoxy group in the poly glycidyl methacrylate‐co‐ethylene dimethacrylate monolith can be a platform for the development of separation and extraction methods based on sequential injection analysis. The epoxy group was functionalized to produce monoliths affording complexing and ion exchange properties. Derivatization with iminodiacetate and sodium sulfite produced weak and strong cation exchangers, respectively. Derivatization with ethylenediamine produced a weak anion exchanger, and the treatment of the ethylenediamine‐modified monolith with chloroacetate produced another weak cation exchanger. All the monoliths also worked as chelating sorbents. The columns were prepared inside 50 × 2.01 mm id fused‐silica lined stainless steel tubing and exhibited permeabilities between 0.76 and 4.92 × 10−13 m2, which enabled the application of flow rates between 5 and 15 μL/s by the syringe pumps used in sequential injection analyzers. These columns separated proteins by cation or anion exchange in a sequential injection chromatograph in both synthetic mixtures and in egg white. Additionally, the online solid‐phase extraction of copper ions was demonstrated in a sequential injection analyzer with the same columns. Postcolumn derivatization with ethylenediamine and spectrophotometric detection was used for the copper detection.

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.