Controlled Porosity Glass Research Articles

Immobilization of laccase from Phlebia radiata on controlled porosity glass

Laccase from the white-rot fungus Phlebia radiata was immobilized on glass beads which were activated by γ-aminopropyl-triethoxysilane. 98% of the protein and 96% of the laccase activity were coupled to the support. The final preparation contained ca. 1 mg of protein per gram of glass beads. The activity of the immobilized enzyme retained after two weeks preservation at +4°C was 100% and at +25°C over 90%. The activity in the presence of organic solvents was rather similar irrespective of the form of the enzyme, free or bound. However, the catalytic activity of the immobilized laccase was less vulnerable against inhibitors such as Cu-chelators and 2,6-dimethoxy-1,4-benzoquinone.

Characterization of ester sulphate in a gypsum-amended podzol using an immobilized sulphatase reactor

An immobilized sulphatase reactor column was successfully used to determine the biochemical stability of ester sulphate in soil organic matter extracted from a podzol amended with gypsum. The sulphatase from Helix pomatia was covalently attached to controlled-porosity glass beads, and the immobilized enzyme was packed into a small glass column. The optimum pH, the time required to reach equilibrium, and the percentage of substrate consumed for the enzymatic hydrolysis of soil ester sulphate (pH 7.7, 90 min, 23–59%) were substantially different from those of p-nitrophenyl sulphate at similar concentrations of substrate (pH 7.0, 40 min, 99%). The striking difference in the biochemical stability and kinetic behaviour between soil ester sulphate and the simple synthetic substrate reflected their different chemical nature and structural features. The amounts of enzymatically hydrolysable (labile) ester sulphate in soil organic matter extracted from the podzol amended with gypsum at rates of 0, 50, and 200 kg S ha-1 were significantly different (P=0.0004), being 0.5, 1.1, and 1.4 μg S ml-1 soil extract (or 5, 11, and 14 μg S g-1 soil), respectively. The labile ester sulphate was not correlated with the total hydriodic acid-reducible organic sulphate with the soil organic matter extracts but with the hydriodic acid-reducible organic sulphate: organic C ratio, which increased as a result of gypsum amendment. This study revealed that input of inorganic sulphate as gypsum substantially increased the accumulation of labile ester sulphate in a podzol.

The preparation of sorbents for the analysis of human antithrombin III by means of high performance affinity chromatography

Antithrombin III (AT III) is an anticoagulant present in blood. It is responsible among other things for blood coagulation and the wrong amount can lead to various health problems. The level of AT III can be taken as an indicator of many pathological states. Due to the very complex composition of blood, high performance affinity chromatography seems to be one of the best methods for the quantitative determination of AT III. The present paper deals with the preparation and properties of sorbents for AT III analysis. The behaviour of the chromatographic packings obtained by the bonding of heparin (used as a complementary ligand interacting with AT III) to cross-linked polysaccharide layers deposited on controlled porosity glass is discussed.

On the correlation between the retention volume of selected compounds and the surface free energy of controlled porosity glasses

The retention volumes of cyclohexane, n-octane, benzene, toluene and ethylbenzene were correlated with the surface free energy of controlled porosity glasses. Linear relationships were found between the retention volume and the film pressure of the adsorbate (corrected with respect to its saturated vapour pressure) and between the natural logarithm of the retention volume and the total surface free energy. The retention volume of saturated chain hydrocarbon (n-octane) did not fit the above-mentioned relationships. This was attributed to dispersive interactions only between surface and n-octane molecules, when compared to benzene homologues. The contribution of dipole-type interactions to the total energy of interactions was found to be ∼20%, when compared to those of π-electrons. The mechanism of n-octane retention which is different from that of benzene homologues presented certain difficulties in the separation of n-octane from benzene and toluene, depending on the magnitude of the specific surface interactions of the investigated controlled porosity glass.

High-performance liquid chromatography of benzodiazepines using sorbents with thermally immobilized Carbowax 20M

The use of siliceous supports (controlled-porosity glass or silica gel) with thermally immobilized Carbowax 20M as sorbents for the separation of benzodiazepines by high-performance liquid chromatography (HPLC) was studied. The physico-chemical and chromatographic properties of these sorbents were compared with those of LiChrosorb DIOL and LiChrosorb RP-18. The results indicate that normal-phase HPLC chromatography of benzodiazepines using sorbents with thermally immobilized Carbowax 20M is a simple and effective method characterized by a simple binary mobile phase, very short column equilibration, high selectivity and a short time of analysis.

Affinity chromatography of 1,4‐β‐glucosidase from trichoderma reesei QM 9414

AbstractThe separation and purification method of extracellular cellobiase and aryl‐β‐glucosidase from Trichoderma reesei by means of affinity chromatography on controlled porosity glass activated by ι‐aminopropyltriethoxysilane and oxiranes are described.

Determination of Free Amino Acids in Cheese by Flow Injection Analysis with an Enzymic Reactor and Chemiluminescence Detector

ABSTRACTThe substrate is degraded enzymatically by L‐amino acid oxidase immobilized on controlled porosity glass. The hydrogen peroxide generated by the reaction is determined by chemiluminescence with an alkaline reagent containing luminol and hexacyanoferrate (III). The log‐log calibration graphs for L‐leucine were rectilinear from 0.025 mM to 1.0 mM (R = 0.9998). The coefficients of variation (rds) for n = 10 were 1.4% and 0.3% for 0.1 mM and 0.8 mM of L‐leucine, respectively. The sample throughout was 40 h‐1. The concentration of free amino acids in cheese samples was 14 to 50 mg L‐leu/g product. The enzyme reactor showed good stability over 4‐months.

Theory of gas-solid adsorption chromatography for heterogeneous adsorbents

Presented here is a general integral equation for describing the total net retention volume in gas-solid adsorption chromatography (GSC). This integral equation contains a distribution function that characterizes the energetic heterogeneity or a solid adsorbent. For the gamma-type distribution function, this integral generates a simple analytical equation for the total net retention volume. Application or this analytical equation for describing the retention or n-hexane and 1-hexene on controlled porosity glass demonstrated its utility for evaluating the physicochemical quantities that characterize gas-solid interactions and the energetic heterogeneity or the adsorbent

Surface free energy components and adsorption properties of some porous glasses

The dispersion and nondispersion components of the surface free energy were determined on the basis of literature adsorption isotherms for water and n-octane on the surface of the controlled porosity glass and thermally treated glasses with chemically bonded Carbowax 20M. Next, using the values of the mentioned components, the work of adhesion of water, n-octane, methanol, carbon tetrachloride and benzene to surface of the glasses and the ratio of the work of adhesion to the work of cohesion were calculated. Applying these calculations a correlation between the thermal treatment time of glasses (before the Carbowax 20 M bonding) and the dispersion and nondispersion components of their surface free energy was found. Additionaly the correlation between the amounts of the liquid adsorbed on the glass surface at constant equilibrium pressure and the ratio of the work of adhesion of the liquid to the glass surface to the work of liquid cohesion were estimated.

The application of new aminoorganic silanes for affinity chromatography of plant peroxidases on vanillin‐liganded controlled porosity glass columns

AbstractIn this work, new packings consisting of home made controlled porosity glass, new self‐prepared aminoorganic silanes and vanillin as a ligand were used for affinity chromatography of some plant peroxidases (donor: H2O2 oxidoreductases; EC 1.11.1.7). The procedure allowed simple and relatively high purification of enzymes. The results were compared with those obtained with the material including commercially available γ‐aminopropyltriethoxysilane.

Evaluation of an Enzymatic Method For Determination of Glucose In Whole Blood Using Flow Injection Analysis With Detection By Chemiluminescence

Abstract A flow injection system for the determination of D-glucose using on-line dialysis is described and its potential use for whole blood measurements is evaluated. Glucose is degraded enzymatically by means of glucose oxidase which is immobilized on controlled porosity glass and incorporated into a small PVC column reactor. the hydrogen peroxide generated by the glucose oxidase is determined by chemiluminescence with an alkaline reagent containing luminol and hexacyanoferrate (III). the detection limit was 0.1 mM glucose with a sampling frequency of 95 h-1 and a standard deviation of less than 1.5%. the enzyme reactor showed little change in activity over a 6 months period of operation. the use of an open tubular nylon coil, in which the glucose oxidase is immobilized to the wall, is also described.

Controlled porous glass (CPG) with reactive epoxy groups as support for affinity chromatography I. Optimization of CPG modification and the binding of glucose with modified surface

AbstractThe selective and complementary interaction between the ligand bound to support surface and isolated substance is the key of the affinity chromatography. This is the reason of the research in the field of certain sorbents. They are obtained by chemical reaction of matrix with proper ligands. It is carried out mainly by using bifunctional substances which make the reaction with the ligand in question possible. This paper deals with the preparation of controlled porosity glass with reactive epoxy groups. In order to obtain such support and avoid application of a proper epoxy silane compound, the double‐step reaction using simple agents was employed. The sorbent syntheses were optimized. The prepared sorbents were applied for coupling some carbohydrates and amino acids.

Dearomatization of lignin derivatives by fungal protocatechuate 3,4‐dioxygenase immobilized on porosity glass

Protocatechuate 3,4-dioxygenase (see protocatechuate: oxygen 3,4-oxidoreductase, EC 1.13.11.3) was isolated from the mycelium of Pleurotus ostreatus (induced with p-hydroxybenzoic acid) and immobilized on controlled porosity glass beads. Four fractions of Na-lignosulfonates (varying in M(r), after chromatography on Sephadex G-50) were treated with the immobilized enzyme. The products after incubation showed the same M(r) as the untreated fractions, but their light absorption at 280 nm considerably decreased. These studies indicate that dioxygenase causes partial dearomatization of lignin macromolecule.

Enzymatic Assay by Flow Injection Analysis with Detection by Chemiluminescence: Determination of Glucose, Creatinine, Free Cholesterol and Lactic Acid Using an Integrated Fia Microconduit

Abstract A miniaturized flow injection system for the determination of D-glucose, L-lactic acid, creatinine and free cholesterol is described. All substrates are degraded enzymatically by means of oxidases which, along with ancillary coenzymes (creatinine assay), are immobilized on controlled porosity glass and incorporated into small PVC column reactors. The hydrogen peroxide generated by the individual oxidases is determined by chemiluminescence with an alkaline reagent containing luminol and hexacyanofer rate (III). The injection valve, flow channels, enzyme reactor and light detector are integrated into a FIA microconduit. The detection limits were 0.03 mg glucose/dl, 0.03 mg lactate/dl, 0.3 mM creatinine and 0.5 mg cholesterol/dl. The enzyme reactors all showed little change in activity over a 3 months period of operation and were found fully compatible with serum samples.

Photochemical transformation of pyrene and benzo[a]pyrene vapor-deposited on eight coal stack ashes

The photochemical decomposition of pyrene and benzo(a)pyrene, as adsorbates deposited from the vapor phase, has been examined on eight coal stack ashes of diverse origin and properties. Similar studies using alumina, silica gel, controlled-porosity glass, and graphite adsorbents also have been performed. Phototransformation of the adsorbates proceeds more slowly on any of the ash substrates than on alumina, silica, or glass surfaces. Those ashes relatively high in carbon and/or iron content are especially effective at suppressing photodegradation of adsorbed pyrene or benzo(a)pyrene. This relationship appears, at least in part, to be associated with the relatively dark colors of those ashes. The apparent acidity of ash surfaces does not appear to be related to the rate of phototransformation of adsorbed polycyclic aromatic hydrocarbons. 40 references, 1 figure, 5 tables.

Factors contributing to intrinsic loading capacity in silica-based packing materials for preparative anion-exchange protein chromatography

Properties of the matrix and stationary phase which affect the intrinsic loading capacity of silica-based packing materials for preparative anion-exchange chromatography of proteins were investigated. Polyethyleneimine-coated controlled porosity glass beads ranging from 100 to 2000 Å in pore diameter were used to evaluate the effects of pore diameter and surface area. Protein binding was found to depend on accessible, rather than total, support surface area. Consequently, wide-pore, high surface area media provide maximum intrinsic loading capacity. Increasing the number of positively charged sites on the stationary phase by increased coating or by quatemization of amines increases hemoglobin-binding capacity.

The Distribution of N-Octadecanol on the Boron Enriched Controlled-Porosity Glass Surface

Article The Distribution of N-Octadecanol on the Boron Enriched Controlled-Porosity Glass Surface was published on January 1, 1986 in the journal Zeitschrift für Physikalische Chemie (volume 267O, issue 1).

Determination of glucose in blood by flow injection analysis and an immobilized glucose oxidase column

A flow-injection system for glucose determination is described. Glucose oxidase is immobilized on controlled porosity glass (CPG) and used in a glass column (2.5 mm diameter × 2.5 cm). The hydrogen peroxide produced by the enzymatic reaction (⩾ 1 × 10 −6 M) is detected by the current produced in a flow-through cell, with two platinum electrodes having a potential difference of 0.6 V. Glucose (0–20 mmol l −1) can be determined in blood plasma either with a dialyser in the system or, better, by incorporating a column of copper(II) diethyldithiocarbamate on CPG before the enzyme column. The results compared well with those obtained by a conventional analyser system. The glucose oxidase column showed little change in activity over a 10-month period.

Influence of the thermal modification of controlled porosity glass on the affinity chromatography of fungal proteins

The properties and the coverage density of chemically bonded phases depend among others on the properties of their supports. Controlled-porosity glasses (CPG) are materials used as a support of bio-active ligands. Their network mainly consist of SiO2 as well as of a small amount of B2O3 and Na2O. The characteristic feature of porous glasses is the possibility of a change in the surface boron concentration leading to the change of the properties of their surface.

A study of the properties of octadecyl phases bonded to controlled-porosity glasses

Liquid chromatography measurements have shown that the properties of C18 films bonded to the surface of controlled-porosity glass particles are different than those bonded on silica gel. The same conditions of the preparation procedure lead to much higher coverage density of the ODS chains on the boron-enriched surface as compared to silica gel. The results show the very high hydrophobicity of the obtained materials.