Porous polymer monoliths for extraction: Diverse applications and platforms

Mesoporous aluminosilica monoliths for the adsorptive removal of small organic pollutants

Water treatment for the removal of organic or inorganic pollutants has become a serious global issue because of the increasing demand for public health awareness and environmental quality. The current paper, reports the applicability of mesoporous aluminosilica monoliths with three-dimensional structures and aluminum contents with 19≤Si/Al≥1 as effective adsorbents of organic molecules from an aqueous solution. Mesocage cubic Pm3n aluminosilica monoliths were successfully fabricated using a simple, reproducible, and direct synthesis. The acidity of the monoliths significantly increased with increasing amounts of aluminum species in the silica pore framework walls. The batch adsorption of the organic pollutants onto (10 g/L) aluminosilica monoliths was performed in an aqueous solution at various temperatures. These adsorbents exhibit efficient removal of organic pollutants (e.g., aniline, p-chloroaniline, o-aminophenol, and p-nitroaniline) of up to 90% within a short period (in the order of minutes). In terms of proximity adsorption, the functional acid sites and the condensed and rigid monoliths with tunable periodic scaffolds of the cubic mesocages are useful in providing easy-to-use removal assays for organic compounds and reusable adsorbents without any mesostructural damage, even under chemical treatment for a number of repeated cycles.

Collection of peptides released from single neurons with particle-embedded monolithic capillaries followed by detection with matrix-assisted laser desorption/ionization mass spectrometry

Characterization of the stimulated release of neuropeptides from brain slices and individual cultured neurons requires efficient collection of the releasate from relatively large volumes of physiological saline. Here, several collection approaches are optimized using particle-embedded monolithic capillaries (PEMCs) with poly(stearyl methacrylate-co-ethylene glycol dimethacrylate) monolith acting as a "glue". Two distinct extraction particles, with either pyrrolidone (PY) or ethylenediamine (EDA) as the functional group on polystyrene backbone, have been embedded into capillaries having an inner diameter of 250 μm. The capillaries act as collection devices for sampling neuropeptide release; the collection protocols are described, and the extraction efficiency of the probes are characterized. Specifically, the binding of angiotensin II from a peptide mixture onto the PY and EDA columns was 16 and 28 pmol, respectively, in a volume of 20 μL of saline. The peptides released from these columns have been characterized via matrix-assisted laser desorption/ionization time-of-flight mass spectrometry with low femtomole detection limits. When the PEMC columns were positioned in close proximity to individual neurons and 50 mM KCl was used as the secretagogue, peptides released from individual identified cultured neurons isolated from Aplysia californica were collected and characterized.

Fundamentals and applications of needle trap devices: a critical review

The needle trap device (NTD) is an extraction trap that contains a sorbent inside a small needle, through which fluid can be actively drawn into and out of by a gas-tight syringe or pump, or analytes can be introduced passively to the trap by diffusion. The needle trap (NT) is a potentially solventless sampling technique/sample preparation and introduction device. Both fluid-borne analytes and particles can be trapped inside the needle and then adsorbed analytes are desorbed in an inlet of analytical instrument and introduced for identification and quantification. The fluid may be either gaseous or liquid. The objectives of this critical review are to summarize the theory of the sampling process for both active and passive time-average extraction modes in addition to outlining the evolution of the technology and main applications.