Styrene-divinylbenzene copolymers from water

Unlike earlier sulfonated styrene/divinylbenzene copolymers, these sulfonated gels can he run in virtually any solvent from water and buffers to pure organics as well as most any mixed solvent systems desired. In aqueous systems they absorb water and in organic solvents they stay swollen by imbibing organic solvents. 

There are a large number of literature references that refer the use of SPE cartridges for the extraction of pesticides from water. There are several comprehensive reviews of the use of SPE, including that by Soriano et al. who discussed the advantages and limitations of a number of sorbents for the analysis of carbamates. Hennion reviewed the properties and uses of carbon based materials for extraction of a wide multiclass range of pesticides. Thorstensen et al. described the use of a high-capacity cross-linked polystyrene-based polymer for the SPE of phenoxy acids and bentazone, and Tanabe et al reported the use of a styrene-divinylbenzene copolymer for the determination of 90 pesticides and related compounds in river water. SPE cartridges are also widely used for the cleanup of solvent extracts, as described below. 

Matsui and Nagair (1980) separated the substrates and the product by reversed-phase HPLC (styrene-divinylbenzene copolymers) at 40°C with a methanol-water (65%, v/v) mobile phase containing 0.01 N HC1 as shown in Figure 9.69. Absorbance at 300 nm was measured, and quantitation was carried out from peaks height measurements. 

The above mentioned polymer-supported oxazaborolidines are prepared from polymeric amino alcohols and borane. Another preparation of polymer-supported oxazaborolidines is based on the reaction of polymeric boronic acid with chiral amino alcohol. This type of polymer can be prepared only by chemical modification. Lithiation of the polymeric bromide then successive treatment with trimethyl borate and hydrochloric acid furnished polymer beads containing arylboronic acid residues 31. Treatment of this polymer with (li ,2S)-(-)-norephedrine and removal of the water produced gave the polymer-supported oxazaborolidine 32 (Eq. 14) [41 3]. If a,a-diphenyl-2-pyrrolidinemetha-nol was used instead of norephedrine the oxazaborolidine polymer 33 was obtained. The 2-vinylthiophene-styrene-divinylbenzene copolymer, 34, has been used as an alternative to the polystyrene support, because the thiophene moiety is easily lithiated with n-butyl-lithium and can be further functionalized. The oxazaborolidinone polymer 37 was then obtained as shown in Sch. 2. Enantioselectivities obtained by use of these polymeric oxazaborolidines were similar to those obtained by use of the low-molecular-weight counterpart in solution. For instance, acetophenone was reduced enantioselectively to 1-phe-nylethanol with 98 % ee in the presence of 0.6 equiv. polymer 33. Partial elimination of... 

The priority phenols (Table 4) in tap and river waters were determined by SPE on line with SEC wi DA-UVD. Tetrabutylammonium bromide was used in the extraction process to increase breakthrough volumes. The mobile phase was CO2 at 40 °C, modified by a gradient of MeOH. LOD was 0.4 to 2 tig L , for 20 mL samples, with good repeatability and reproducibility between days (n = 3) for real samples spiked with 10 [xgL . Seven pollutant phenols, 107a-f and pentachlorophenol, were determined by lEC with a basic SAX resin (styrene-divinylbenzene copolymer with quaternary ammonium groups) and single channel UVD. Resolution of overlapping peaks was carried out by inverse least-squares multivariate calibration. LOD was 0.6 to 6.6 ng, with better than 90% recovery from spiked pure water and 83% from river water. No extensive clean-up was necessary . ... 

Next, condition either the silica-based bonded phases or the styrene-divinylbenzene copolymers with methanol to wet and activate the sorbent for good mass transfer when the sample is passed through the sorbent. Rinse the methanol from the sorbent with deionized water. Several bed volumes should be sufficient to displace the majority of methanol and is comparable to that used in reversed-phase SPE. 

A specific application of environmental SPE is sample preparation of extra-large volumes (from 10 to 100 L). This work was pioneered in the early 1970s by Junk and co-workers (1974) for the analysis of trace organic compounds in water using styrene-divinylbenzene copolymers (XAD-2 resin from Rohm and Haas) and by Thurman and Malcolm (1981) and Leenheer and Stuber (1981) for the analysis of natural organic substances in water (humic substances). One can obtain the XAD resins from Supelco (Appendix Products Guide) and still follow the protocol of this early work for the isolation of contaminants and humic substances from large volumes of water (10-1000 L of water). 

A series of commercial styrene-divinylbenzene copolymers called Amberlite XAD (Rohm and Haas Co., Philadelphia) has been used as a base to immobilize a variety of complexing agents (269). On XAD-2, tri-/i-octylamine (270), several ferroin-type chromogens (277), and phenylarsonic acid (272) have been used to concentrate and separate several trace species from seawater and fresh water. An EDTA ligand (273) and phenylarsonic acid on XAD-4 can also extract trace metals such as Cr(III), Pb(II), Hg(II), U(VI), Zr(IV), and Zn(II) at the sub-parts-per-billion levels, even in the presence of excess calcium and magnesium if the pH is less than 3.0. 

GPC is the most predictable mode of HPLC. The separation is based on the size of the sample in solution, not the molecular weight. There must not be any interaction with the column packing material (adsorption, partition, etc.), as there is in other modes of HPLC. GPC column packings are particles of cross-linked gel that contain surface pores. The sizes of these pores are controlled and vary from small to large. They act as a molecular filtration system. The most widely used gels are styrene/divinylbenzene copolymers for organic solvent-soluble polymers and acrylate gels for water-soluble polymers. 

Therefore, the online approach is generally preferred to the off-line mode. Online SPE has been applied to the determination of phenols in water samples using small precol-mnns with different adsorbents such as octadecyl-bonded silica [50,133-135], styrene-divinylbenzene copolymers PLRP-S or PRP-1 [133-145], and graphite carbon [134,146]. Recently, Cis and PSDVB extraction disks have been applied to the off-line extraction of phenols from water samples [147-149]. 

Typical examples of covalently cross-linked networks are a styrene-divinylbenzene copolymers swollen in an organic solvent and ion-exchange resins made from cross-linked polystyrene sulfonate, poly(/ -aminostyrene), or 2-hydroxyethyl methacrylate-ethylene glycol dimethacrylate copolymer swollen in water, which is the typical material used for soft contact lenses. Table 1 gives a classification of gels. 

Highly hydrophobic sorbents including porous carbon and copolymers of styrene and divinylbenzene (SDB) were widely investigated for environmental applications. The particle-loaded membranes containing modified SDB particles with surface sulfonic acid groups were successfully used for recovering different alcohols, phenols, aldehydes, ketones, or esters from aqueous samples [221]. Carbon-based PLM were also used for isolation of highly polar pesticides from water [222]. 

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