Porous polymer monoliths (PPM) have been shown to be well suited to the extraction and separation of macromolecules, largely due to their excellent flow properties.However due to the primarily macroporous structure extraction and separation of small molecular analytes using PPM remains as a challenge.To address this challenge we report a new approach for the synthesis and fabrication of reversed phase bimodal porous polymer monolith via thermally-initiated free radical polymerization using divinylbenzene (DVB) as a crosslinking monomer and a secondary oligomeric compound as a porogen providing the monolith with mesoporosity within the macroporous structure. The secondary porogen allows tuning of the structure without affecting the macroporous properties of the monolith, facilitating good permeability and making this material a unique stationary phase in solid phase extraction (SPE) techniques. A quantitative analysis was conducted to observe the optimum binding capacity of the monolith by reversed phase high performance liquid chromatography (RP-HPLC) using synthetic peptides of molecular weight from 300-700 Da. The results indicate that the novel monolith material has an optimum binding capacity of 250-100 mg/g and recovery ranged from 50-95% respectively for analytes within the cut off range of 500 Da compared to 80-150 mg/g and 50-67% for commercially available polymer particle based SPE sorbents. To characterise the porous structure, the materials were studied by scanning electron microscopy (SEM) and gas physisorption analysis. The SEM images display the clustered globule morphology typical of an organic polymer monolith and the nitrogen- adsorption-desorption isotherm indicates the presence of disordered mesopores of 3nm and a specific surface area of 606 m<sup>2</sup>/g. Due to the unique porous structure, there is restricted access for large analytes like protein which reduces the binding capacity of macromolecules. Therefore, the novel monolithic sorbent can be considered as a prospective sorbent for SPE with improved selectivity of isolation of the target analytes, higher adsorption capacity and mechanical stability.

Bimodel porous polymer monolith as a sorbent for solid phase extraction technique

256th National Meeting (2018)

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