Sponge-nested polymer monolith sorptive extraction

Polymer monoliths are an alternative to traditional particle-packed supports used in solid-phase ex-traction because of their ease of preparation, high porosity, and pH stability. They often required the attachment of monoliths to a support, such as the internal walls of a column to enable their use for sample preparation. Applications of free-standing polymer monoliths are rarely found because of their limited mechanical stability. Herein, divinylbenzene monoliths were polymerised within a com-mercial melamine-formaldehyde sponge using different polymerisation times. The sponge-nested poly-mer monoliths are highly robust, and their size and shape can be easily adjusted for desired applica-tions. The prepared sponge-nested polymer monoliths had surface areas in the range of 237 m 2 g -1 to 369 m 2 g -1. A melamine-formaldehyde sponge cut into 1 cm3 cubes were used to template the polymer monoliths. Miniaturized monoliths with a size of 0.125 cm3 were directly cut from the larger cubes without compromising the integrity of the porous monolith structure. The resulting nested mono-lith sorptive extraction (NMSE) supports were applied for the extraction of the endocrine disruptors bisphenol A, 4-tert-butylphenol, and 4-tert-octylphenol. The prepared sponge-nested monoliths are low-cost (40 monoliths/AU$). NMSE was carried out by the direct immersion of the monoliths in the aqueous standards/samples, requiring only an orbital shaker for the extraction procedure. Best performance was obtained for polymer monoliths polymerized for 6 h, enabling limits of detection of 5.6 to 6.5 mu g L -1 for the selected analysis using HPLC-UV.(c) 2022 Elsevier B.V. All rights reserved.

Automated summary

Polymer monoliths are a promising alternative to traditional supports used in solid-phase extraction. In this study, divinylbenzene monoliths were embedded within a commercial melamine-formaldehyde sponge to enhance their mechanical stability. The resulting sponge-nested polymer monoliths demonstrated high robustness and adjustable size and shape for various applications. These monoliths were successfully used for the extraction of bisphenol A, 4-tert-butylphenol, and 4-tert-octylphenol. The developed nested monolith sorptive extraction (NMSE) supports are cost-effective and can be directly immersed in aqueous samples for extraction. The best performance was achieved when polymerizing the monoliths for 6 hours, with low limits of detection using HPLC-UV analysis.