Microporous hypercrosslinked polystyrene Styrosorb as a restricted access packing in sample clean-up for high performance liquid chromatography. Part I: Evaluation of restricted access properties

Summary Styrosorb is a beaded microporous polystyrene with particle sizes between 2 and 4 m. In spite of hypercrosslinkage the material was seen to swell in organic solvents. The native material is functionalized with Tris-groups at the outer surface of the particles. The average pore diameter was determined as 1.45±0.3 nm from size exclusion data using polystyrene and polyethylene standards in THF. The reversed phase behavior of the restricted access phase Styrosorb was investigated by injection of two test mixtures. Mixture I contained five aromatic amines, mixture II consisted of Amperozide^R and four related compounds. The optimum range of mobile phase composition was assessed so that analytes were separated whilst any proteins present were eluted unretained. Due to the small particle size short columns of 29×4 mm can be used for both sample clean-up and analytical separation of Amperozide^R and its metabolite.     

Physicochemical and adsorption properties of hypercross‐linked polystyrene with ultimate cross‐linking density

The paper describes unexpected properties of hypercross‐linked polystyrenes with ultimate cross‐linking degrees of 300, 400, and 500%, where three, four, or five methylene links, respectively, could bind each polystyrene phenyl ring to its spacious neighbors. The polymers exhibit a strong electron spin resonance signal, unusual spectra in IR, UV, and visible ranges, and they are not typical dielectrics. The nonfunctionalized hypercross‐linked polymers absorb significant amounts of inorganic acids, salts, and bases due to interactions of protons or other cations with electron‐donating fragments of the aromatic network with the high extent of mutual connectivity and also due to dispersion interactions of anions with the polymer matrix.     

Synthesis and sorption ability of telogenated hyper-cross-linked polydivinylbenzene networks

Synthesis and properties of hyper-cross-linked polymer networks prepared by radical polymerization of commercial divinylbenzene in oxylene, a good solvent and a powerful telogen, are reported. The permeability of hyper-cross-linked networks is evaluated by adsorption of bioactive molecules significantly differing in size. High sorption capacity for Cephalosporin C makes the polymers prepared promising for pharmacology and biotechnology.     

1H NMR cryoporosimetry of swollen hypercrosslinked polymers

The porous structure of two laboratory samples of hypercrosslinked polystyrene networks with a crosslinking degree of 200%, the commercial hypercrosslinked sorbent MN-270 (Purolite Int.), and macroporous polystyrene sorbents Amberlite XAD-4 and Amberlite XAD-1600 were investigated by means of ¹H NMR cryoporosimetry. It was determined that the signal intensity of benzol, dioxane, dichloroethane and water protons previously frozen in polymer pores increases during solvent melt. Dependencies of the integral proton signal intensities on the sample temperature obtained in various solvents are discussed in terms of sample micropore accessibility and solvent—polystyrene interaction energy. Pore dimensions are estimated using the melting temperature value of ice according to the Gibbs—Thomson equation. We conclude that the obtained distribution curves reveal all hypercrosslinked polymers to be mainly microporous with diameter distribution maxima around 10 Å. It is shown that along with pores 120 Å in diameter, XAD-4 has a considerable amount of micropores. In contrast, XAD-1600 is ranged as a mesoporous sorbent.     

Use of the hyper-crosslinked polystyrene sorbents “Styrosorb” for solid phase extraction of phenols from water

The analytical HPLC procedure for the quantitation of trace amounts of phenol and chlorophenols in aqueous media has been supplemented with the on-line preconcentration of phenols in a sorption cartridge packed with microporous hyper-crosslinked polystyrene. The cartridge is coupled in succession with a reversed-phase analytical column, which is operated isocratically in an aqueous acetonitrile eluent (1:1, v/v). Phenol concentrations down to 0.5 μg/l can be detected using a simple 254 nm UV detector. Biporous hyper-crosslinked polystyrene-type sorbents were shown to effectively purify about 100 bed volumes of water from phenol under neutral or acidic conditions and linear flow rates up to 4 cm/min, which could be of great practical importance. Rapid and quantitative elution of sorbates from the hyper-crosslinked polystyrene materials is facilitated by the unique ability of the latter to additionally swell with organic or aqueous-organic eluents applied.