Polystyrene-divinylbenzene Copolymer Research Articles

Analysis of the DNA adducts of phenyl glycidyl ether in a calf thymus DNA hydrolysate by capillary zone electrophoresis-electrospray mass spectrometry: evidence for phosphate alkylation.

Calf thymus DNA was reacted in vitro with phenyl glycidyl ether (PGE) and was hydrolysed enzymatically, to the 5'-monophosphate nucleotides using deoxyribonuclease I (DNA-ase I) and nuclease P1. The adducts were concentrated using solid phase extraction (SPE), on a polystyrene divinylbenzene copolymer in order to remove the unmodified nucleotides. The adducts could be identified using capillary zone electrophoresis-electrospray tandem mass spectrometry (CZE ES-MS/MS), using sample stacking. In addition to the base alkylated 2'-deoxynucleotides present in the DNA-hydrolysate, also phosphate alkylated 2'-deoxynucleotide adducts were identified for TMP and dAMP. An additional adduct, dUMP alkylated on the uridine moiety was found originating from the hydrolytic deamination of dCMP alkylated on N3 of the cytosine moiety. Enzymatic hydrolysis using nuclease P1 was incomplete as shown by the presence of dinucleotides alkylated on the base moiety. They were successfully hydrolysed to the corresponding 2'-deoxynucleotides by snake venom phosphodiesterase (SVP). Data are shown indicating that alkylations on the pyrimidine bases were more resistant to enzymatic hydrolysis with nuclease P1 than the purine alkylated products.

Analysis of the DNA Damage Induced by Phenyl Glycidyl Ether Using Capillary Zone Electrophoresis–Electrospray Mass Spectrometry

Thein vitroadduct formation between phenyl glycidyl ether (PGE) and calf thymus DNA was inves-tigated. Agarose slab gel electrophoresis of DNA incubated with PGE revealed that nearly all high-molecular-weight species were degraded after 10 h of incubation. After DNA precipitation the reaction products present in the supernatant were subjected to a solid-phase extraction on a polystyrene divinylbenzene copolymer, enabling analysis on capillary zone electrophoresis (CZE), using sample stacking. These reaction products were mainly produced during the first 10 h of incubation, indicating that these products result from the DNA degradation. On the other hand, analysis of the adducts present in the enzymatic digest of the DNA pellet revealed that these adducts were formed only after 10 h of incubation. The reaction products present in the DNA supernatant were identified by on-line coupling of CZE to electrospray tandem mass spectrometry. Three major reaction products resulted from phosphate alkylation, as proven by the analysis of the corresponding low-energy CAD product ion mass spectra. This phosphate alkylation results in phosphotriesters which readily hydrolyze, resulting in DNA strand breaks.

Sulfoacylated polystyrene–divinylbenzene copolymers as resins for cation chromatography: Influence of capacity on resin selectivity

To compare the effects of different ion-exchange capacities, a highly crosslinked polystyrene–divinglbenzene resin of 5 μm has been functionalized by sulfoacylation with exchange capacity varying from 0.1 to 0.75 mmol/ml. Theoretically, the separation factor of two cations with the same charge should be independent of the exchange capacity. To study the influence of specific capacity, the retention behavior of a mixture of nine divalent cations (Cu, Pb, Zn, Ni, Co, Cd, Mn, Ca, Mg) has been investigated with tartaric acid–sodium hydroxide as eluent. The logarithm of adjusted retention times was found to be a linear function of the specific capacity. However, the slopes differ significantly from the presumed value of 2 for divalent cations. The observed trend is correlated to the sequence of diameters of the hydrated ions obtained from electrochemical measurements. Considering the deviations from the nominal charge the observed dependencies of separation factors on specific capacity can be explained semiquantitatively.

Separation of actinides by means of HPLC

A procedure is described separating, identifying and determining the actinides (An) U, Np, Pu, Am and Cm in the presence of the lanthanides (Ln) La, Ce, Pr, Nd, Pm, Sm, Eu and Ho on an analytical scale. It is based on high-pressure liquid chromatography (HPLC) combined with a dual on-line detection system and is accomplished within a short time, in one step and under isocratic conditions (for An). The separation was carried out on a strongly acidic and highly capacitive cationic exchange resin on a polystyrene divinylbenzene copolymer (Aminex A9, co. BioRad) basis. Radionuclides emitting α- and β-particles are detected on-line using a custom-made solid scintillation flow-through cell. Inactive components are monitored by colour reagent complex detection (Arsenazo III, λ-648 nm) with a VIS detector placed in series.

Automated derivatization for on‐line solid‐phase extraction‐gas chromatography; phenolic compounds

AbstractAn automated system for derivaatization was coupled on‐line with solid‐phase extraction‐gas‐chromatography (SPE‐GC). The system was optimized for the determination of phenol and chlorinated phenols in aqueous samples. The test analytes were acetylated with acetic anhydride; proper buffering of the sample was a critical factor. Next, the phenol acetates were enriched on a SPE cartridge and transferred to a GC; two appraoaches were studied. In the first approach, the derivatives were enriched on disposable C18 cartridges (ASPEC type) and desorbed with methylacetate. Aan aliquot of the final eluate was injected on‐line the GC by means of a loop‐type interface. In the second approach, trace enrichment was performed on 10 × 2 mm i.d. LC‐type precolumn packed with polystyrenedivinylbenzene copolymer (PLRP‐S) this precolumn was dried with a mitrogen purge and the phenol acetates were desorbed with ethyl acetate which was injectedon‐line into the retention gap of the GC under partially concurrent solvent evaporation (PCSE) conditions. The Derivatization‐SPE‐GC system which was based on the loop‐type interface has the advantage of simplicity and easy operation, the main drawback is the impossibility to determine phenol acetates which elute prior to trichlorophenol acetates. With the derivatization‐SPE‐GC approach using PCSE‐based desorption, even the most volatile analyte of the test series, phenol acetate, can be determined successfully. The entire procedure, including the derivatization step, was fully automated and integrated in one set‐up. The precision data for the integrated on‐line derivatization‐SP‐FID system were fully satisfactory, with RSD values of 1–12 % at the 1 μg/1 level. When a sample volume of 2.2 ml was analyzed, The detection limits for the chlorinated phenol acetates were in the 0.1–0.3 μg/1 range.

Equilibrium and Kinetic Studies on Ligand Exchange Reaction of Aluminum(III)-5-sulfoquinoline-8-ol Complex with Fluoride Ion by Reversed-Phase Ion-Pair Liquid Chromatography.

The reversed-phase ion-pair liquid chromatographic behavior of the complex of aluminum ion with 5-sulfoquinoline-8-ol (HQS) was investigated on the column packed with a polystyrene-divinylbenzene copolymer with the mobile phase containing fluoride ion. It was found that the fluoride ion replaces one or two HQS molecules from the aluminum-HQS complex to form the mixed ligand complexes, which resulted in the appearance of two or more peaks in the chromatograms obtained for aluminum ion. The compositions of the mixed ligand complexes were estimated from the dependence of the areas of the peaks on the mobile phase concentrations of HQS and fluoride ion. The equilibrium and rate constants for the ligand exchange reaction were also evaluated and the reaction mechanism was presented. Aluminum ion could be completely separated from gallium ion by utilizing the ligand exchange reaction.

Determination of chlorophenols by micellar electrokinetic chromatography with electrochemical detection

A method has been developed for the determination of chlorophenols by micellar electrokinetic chromatography (MEKC) coupled with electrochemical detection. A mathematical model was used to predict optimal separation conditions; 17 of the 20 compounds of interest (19 chlorophenols and phenol) were baseline-separated in a 50 mmol l −1 ACES buffer at pH 6.1, with 22 mmol l −1 sodium dodecylsulfate. Detection was performed with a graphite-epoxy working electrode at a potential of 800 mV vs. Ag/AgCl. A palladium metal union was used to decouple the separation field from the electrochemical cell. A compensating pressure was applied to preserve the flat electroosmotic flow profile during analysis. Plate numbers up to 150 000 were obtained. The applied detection potential was shown to have an influence on the width of the peaks. Because the noise on the signal increased with the applied separation voltage, an optimum had to be found between detection limits and analysis time. Detection limits were in the order of 10 μg l −1, one to three orders of magnitude lower than in with UV detection. The repeatibility was typically ±0.9% for the (electroosmotic flow corrected) mobility and ±4% for the peak area ( n = 7). Combined with off-line solid-phase extraction on a column with a polystyrene-divinylbenzene copolymer packing (PLRP-S), the method proved suitable for the analysis of river water samples. When using an internal standard, the average repeatability of the peak area was ±6% for 14 compounds ( n = 5). With this preconcentration-method, detection limits lower than 0.1 μg l −1 in 100 ml river water sample were obtained.

Equilibrium and Kinetic Studies of Ligand-Exchange Reaction of Aluminum(III)-5-Sulfoquinoline-8-ol Complex with Phosphate Ion by Reversed-Phase Ion-Pair Liquid Chromatography

The reversed-phase ion-pair liquid chromatographic behavior of complexes of alummum(lll) with 5-sulfoquinoline-8-ol (HQS) on a column packed with a polystyrenedivinylbenzene copolymer is investigated with eluents that contain phosphate buffer. The aluminumdll)-HQS complex results in two peaks on the chromatograms; the heights of the peaks strongly depend on the pH of the eluent, the concentrations of HQS and phosphate buffer in the eluent, and the column temperature. The results obtained are interpreted according to the ligand-exchange reaction of aluminum(lll)-HQS with H 2 PO 4 - or HPO 4 2 in the eluent. The compositions of the mixed ligand complexes are determined, and the equilibrium and rate constants for the ligand-exchange reaction are estimated.

High-performance liquid chromatographic determination of 14C-labelled terbuthylazine and principal degradates in percolation water and soil extracts from leaching experiments

A new very porous polystyrene-divinylbenzene copolymer with large surface area as an adsorber for solid-phase extraction (SPE), was used for the analyses of terbuthylazine and principal degradates. It showed good recovery rates even for the dealkylated hydroxy metabolites. The polymer was treated similarly to a reversed-phase material, sample of 1000 ml showed no breakthrugh for most of the terbuthylazine degradates. A detection limit of 0.1 μg/l could be reached even for the most polar compounds (de- tert-butyldeethylterbuthylazine and de- tert-butylhydroxyterbuthylazine) with recovery rates of 22 and 30%. Percolated water and soil extracts from column experiments, obtained with water and methanol, were analysed using the copolymer sorbent. Analyses were performed on a HPLC system with UV-Vis detection and a scintillation counter. The compounds were separated on a RP-8 column with an acetonotrile-phosphate-buffer gradient. In addition to terbuthylazine applied 2 months prior to extraction, deethyl- and hydroxyterbuthylazine were detected in the soil extracts; de- tert-butylterbuthylazine was found only in traces.

FT-Raman Measurements on Cation-Exchange Resins

The utility of FT-Raman spectroscopy in characterizing ion-exchange resins has been demonstrated. Measurements have been made on strong acid-type cation-exchange resin beads of a sulfonated polystyrene-divinyl benzene copolymer. Spectra are compared for the resin with 10 different cations. Classical least-squares fitting is used to quantitate the amounts of different cations in binary mixtures. On-column determinations are demonstrated for displacement of H+ by Na+ and Na+ by Ag+.

EPR-spin probe studies of model polymers: separation of covalent cross-linking effects from hydrogen bonding effects in swelled Argonne premium coal samples

The swelling behavior of 2-12 % cross-linked polystyrene-divinylbenzene (PSDVB) copolymers was examined by an EPR-spin probe technique. It was observed that the mechanism of spin probe inclusion was the intercalation into the matrix rather than diffusion into the pores. The disruption of van der Waals forces between adjacent aromatic rings appeared to be the primary mechanism for pyridine swelling of PSDVB. By comparing the data to results from coal swelling studies it was also inferred that the extent of hydrogen bonding in coal will have a much greater impact on its swelling properties than its covalently cross-linked character

Soluble and immobilized enzymes in water-miscible organic solvents: glucoamylase and invertase

The efficiency of enzymes in organic solvents is determined by the catalytic parameters, which mostly are changed in comparison with those in aqueous solutions, as well as by reversible and irreversible denaturation of the enzyme protein. The interplay of these processes was studied on soluble and immobilized glucoamylase and invertase in mixtures of buffer and several water-miscible solvents such as methanol, glycerol, dimethylformamide, and dioxane. A comparison of the catalytic activity in 50 or 30% (v/v) solvents with the extent of irreversible inactivation during the time of assay showed that the solvents act on the catalytic parameters of the enzymes and their conformational stability in different ways. Irreversible inactivation is especially strong in dimethylformamide, whereas glycerol does not induce denaturation but strongly reduces the catalytic efficiency. Striking effects were observed in dioxane, where high stability to irreversible denaturation but strong reduction of catalytic power were observed. In all solvents K m values were more affected than V max values, suggesting that reversible denaturation plays an inferior role in activity losses. Similar effects of the individual solvents were also observed after immobilization of the enzymes by covalent binding to a macroporous aminomethyl polystyrene-divinylbenzene copolymer or a macroporous aminopropyl silica. In all cases, however, immobilized enzymes showed better long-term stability than the soluble enzymes.

Analysis of chlortetracycline by high performance liquid chromatography with postcolumn alkaline-induced fluorescence detection.

A high performance liquid chromatographic method for the analysis of chlortetracycline (CTC) using postcolumn fluorescence detection has been developed. After chromatographic separation of CTC on a polystyrene-divinylbenzene copolymer column, a highly fluorescent derivative isochlortetracycline (iso-CTC) was formed postcolumn in an on-line reaction coil with the addition of 25% NaOH (w/v). Chromatographic separation was achieved on a PRP-1 column, 15 cm x 4.6 mm, with 27:73 acetonitrile:0.2% perchloric acid (v/v), at 1.0 mL/min. Fluorescence derivatization was achieved by the on-line addition of 25% NaOH (w/v), at a flow rate of 0.2 mL/min, into the column eluant in a post-column reaction coil. The reaction coil was 9 m of teflon (1/16 in o.d., 0.3 mm i.d.) knitted into a six-sided coil. The fluorescent derivative was detected at lambda ex 355 nm and lambda em > 389 nm. Using this method after a simple sample cleanup, CTC can be detected in milk at 0.04 micrograms/mL, which is comparable to that obtained by microbiological assays. The detection method was linear between 0.02 micrograms/mL and 4 micrograms/mL. Because of the chromatographic separation, the method is more selective than microbiological assays and more sensitive than ultraviolet detection. With the chromatographic system described, the keto tautomeric forms of CTC and 4-epi-CTC are separated in a system which minimizes their formation on-column. In acidic aqueous organic solutions, the keto tautomer of CTC is the only product formed to any significant amount.

Automated analyses of non-ionic surfactants in terms of hydrophobic and polyoxyethylated chain lengths

A novel automated system for the analysis of polyoxyethylated (POE) non-ionic surfactants is proposed, which is capable of providing information on both hydrophobic and POE chain lengths. A polystyrene—divinylbenzene copolymer gel is effective for the hydrophobic chain analysis because the separation is not influenced by the distribution of POE chains. On the other hand, a K +-form cation-exchange resin is effective for elucidating the distribution of POE chains. An automated system was constructed by combining these two separation methods, and was applied to the analysis of the distributions of hydrophobic and POE chains in a commercial Brij 35.

High-performance liquid chromatographic determination of penicillin G, penicillin V and cloxacillin in beef and pork tissues

The objective was to develop confirmatory high-performance liquid chromatographic methods for peniccilin residues in animal tissues with detection limits of ⩽10 ng.g. A previously described procedure was modified by using a larger sample size and isocratic analysis. Tissues (15 g) were blended with 45 ml of water and 20 ml of homogenate were mixed with 40 ml acetonitrile and filtered. The filtrate (30 ml) was mixed with 10 ml. of 0.2 M H 3PO 4 and extracted with methylene chloride. The combined methylene chloride layers were mixed with acetonitrile and hexane, washed with two 4-ml portions of water and then extracted with four 1-ml portions of 0.01 M phosphate buffer (pH 7). The combined buffer extracts were concentrated to 1 ml under reduced pressure. Analysis was isocratic during 0.01 M phosphate buffer (pH 7)-acetonitrile with proportions 85:15 (penicillin G), 82:18 (penicillin V) or 78:22 (cloxacillin). A polystyrene-divinylbenzene copolymer column, 150 × 4.6 mm I.D. (Polymer Labs. PLRP-S), was used with a flow-rate of 1 ml/min and detection at 210 nm. The presence of peniccilins was confirmed by treating a duplicate sample with penicillinase. Recoveries were > 90% in most instances. Detection limits wee 5 ng/g in muslce and higher in liver and kidney. The prcedure is a simple and sensitive method for confirming the presence of penicilins in animal tissues.

Behavior of polymer-supported tomatine toward cholesterol in the presence or absence of butter oil

Insoluble carboxy-functionalized polystyrene-divinylbenzene copolymers were bonded to tomatine. Tomatinized polymers removed cholesterol from hexane solutions of butter oil or cholesterol

Image analysis of macroporous polystyrene sorbents using electron spectroscopic imaging to enhance mass contrast. The architectural relationship between polymer porosity and absorption capacity

SUMMARYWe describe the microscopical analysis of two polystyrene divinylbenzene copolymers (PS‐DVB) made using 20 and 55% (v/v) DVB cross‐linker respectively, in which the hydrated structure of each polymeric material solvated in water is preserved by employing very rapid freezing and low‐temperature freeze‐drying techniques. Using the zero‐loss mode of electron spectroscopic imaging to enhance the contrast of unstained polymer sections, we introduce some novel methods for the application of computer‐assisted image analysis for routine examination of polymer pore structure. We also relate these parameters to the ability of the two polymers to absorb nanometre‐sized particles—neutral colloidal gold particles and cationized ferritin. Both methods will be invaluable in the structural analysis of porous polymers, but particularly for comparative analyses of macroporous sorbents.

Sorption and separation of palladium, platinum and gold chlorocomplexes by means of a dipicolinic acid polystyrene-based chelating resin

A chelating ion-exchange resin containing dipicolinic acid as functional group and based on microporous chloromethylated cross-linked polystyrene-divinylbenzene (2 %) copolymer has been prepared. Its sorption and desorption characteristics for Pd(II), Pt(II), Pt(IV) and Au(III) have been studied in aqueous chloride solutions under a number of experimental conditions, both in batch and in column, at room temperature and constant ionic strength ( μ = 1 mol/l, KCl/ HCl). In column operations at pH 6, Pd(II) can be separated from Pt(H) or Pt(IV) owing to the different rate of formation of the immobilized chelated species. From a mixture of Pd(II, Pt(IV) and Au(III) at pH 6, Pt(IV) flows unaffected, whereas Au(III) and Pd(II) are both retained and successively separated by selective elution. From the same mixture at pH ≤ 0 only Au(III) is sorbed by anionic exchange.

The growth of sparingly soluble salts on polymeric substrates

Polymers such as the commercially available Porapak-N and synthetically prepared polystyrene (1.5% w/w) divinyl benzene copolymer and polystyrene have been converted into substrates appropriate for the deposition of hydroxyapatite (Ca 5(PO 4) 3OH, HAP) by the introduction of various phosphate groups on their surface. The investigation was carried out at sustained supersaturation at 37°C for the styrene (1.5% w/w) divinyl benzene copolymer and at 25°C for Porapak-N and polystyrene. In the former case the apparent crystal growth order was found to be 1.25 as for the growth on HAP seed crystals. Increasing the content of phosphate in the surface resulted in higher rates of mineralization. At 25°C higher apparent orders of reaction were observed possibly due to the microporous structure of the polymers employed.

Electrometer for repeated charge exchange measurements between a microparticle and a surface: Effect of water adsorption

We report a new electrometer which allows the study of contact charging between a single microparticle and a metal surface. The electrometer is based on an electrodynamic levitator-trap and has a leakage current of about 10 −23 A. The electrometer is applied to the study of the contact charging of spherical polystyrene-divinyl benzene copolymer particles against a Ni surface under ambient and a “dry” N 2 atmosphere. Significantly reduced charge exchange after eliminating water molecules from the particle would be strong evidence for an ionic charge exchange mechanism. Through a combination of gravimetric and light scattering measurements we have determined both the amount of water accreted in a humid atmosphere and the maximum amount of water that could be on the surface of the particle. Our experiments indicate approximately constant charging, independent of the amount of water on the particle.