Showing papers on "Buffer solution published in 1978"

Hydrolysis of some N-alkylmaleimides

Abstract: The kinetics of the hydrolysis of maleimide (MI), N-methylmaleimide (MMI), N-ethylamleimide (EMI), and N-hydroxymethylmaleimide (HMMI) were studied spectrophotometrically in pH-controlled buffer solution over the temperature range 10–50 °C. The rate of hydrolysis is proportional to both the concentration of N-alkylmaleimide and that of hydroxide ion in the pH region between 7 and 9, and is independent of pH below pH 4. The catalytic rate constants for alkaline hydrolysis increase in the order: HMMI > MI > MMI > EMI. The entropies of activation for the hydrolysis at pH 7–9 are large and negative ranging from –132 to –162 J mol–1 K–1 and both the enthalpies and the entropies of activation increase in the order: EMI > MMI > MI > HMMI. The effect of substituent on nitrogen on the rate of hydrolysis is explained satisfactorily by Taft's ρ*σ* relationship, with a value of ρ* of 0.05 at 30 °C. The experimental results can be explained by a bimolecular mechanism, in which nucleophilic attack by hydroxide ion on N-alkylmaleimide is the rate-determining step. The hydrolysis products are N-alkyl-maleamic acids.

Enhanced intestinal permeability to macromolecules. I. Effect of monoolein-bile salts mixed micelles on the small intestinal absorption of heparin.

Abstract: The effect of monoolein-bile salts, sodium glycocholate and sodium taurocholate, mixed micellar solutions on the intestinal absorption of heparin was investigated using the in situ closed loop of the rats. It was observed that these mixed micellar solutions extremely enhanced the absorption of heparin and that the mixed micellar solution prepared with distilled water facilitated the intestinal absorption of heparin more markedly than that prepared with pH 6.5 phosphate buffer solution. This difference between mixed micellar distilled water solution and mixed micellar buffer solution was studied by ultrafiltration, pretreatment with the micellar and mixed micellar solutions, and gut exsorption. Enhanced permeability is discussed from the standpoints of intraluminal interaction between the mixed micelles and heparin molecules, and an alternation in the permeability of the mucosal membrane.

Light‐activated hydrolysis of GTP and cyclic GMP in the rod outer segments.

Abstract: 1. The hydrolysis of guanosine triphosphate (GTP) and the consequent formation of guanosine diphosphate (GDP) and phosphate (P1) are activated by light in a suspension of broken retinal rods: the hydrolysis rate with GTP in the micrometer concentration range is 2.5-3.5 n-mole/min per mg of rhodopsin in the preparation. 2. The ionic composition of the medium suspending the rods is not critical: the hydrolysis is present in NaCl saline solution with MG2+ as well as in Tris-HC1 buffer solution, and with the chelating agent EDTA. 3. The ionic strength is critical: the effect is reduced when the broken rods are suspended in a low salt mannitol solution, and is altogether abolished when they are separated from the mannitol solution; it reappears when the mannitol solution is added again in the presence of salts. An element essential for the effect is thus reversibly released in the mannitol solution. No hydrolytic activity on GTP, however, is found in the mannitol soluble fraction. 4. The cyclic nucleotide phosphodiesterase is eluted from the rods in the mannitol solution, and is reaggregated to the rods in the presence of salts; once recombined with the rods, it can be activated by light. 5. The activation of the phosphodiesterase by light is present in the absence of added nucleotide triphosphates.

Dynamic aspects of contact angle measurements on adsorbed protein layers

Abstract: Contact angle measurements using drops of paraffin oil have been performed on polystyrene (PS) substrates, coated with human serum albumin (HSA) or human fibrinogen (HFb), immersed in buffer solution. The contact angle appeared to be time dependent. The final value for HSA-coated substrates was 50° ± 5° and for HFb-coated substrates 130° ± 10° (measured through the oil phase). From measurements of the interfacial tension at oil/buffer interfaces on passing HSA-coated substrates and from measurements using radio-labeled HSA in such experiments, it may be concluded that an adsorbed layer of HSA on PS can turnover from the PS substrate to the oil/buffer interface. The difference in behavior between PS substrates coated with HSA and PS surfaces coated with HFb is attributed to association of the HFb molecules upon adsorption at the PS/buffer interface, whereas the stronger intramolecular forces in HSA do prevent this behavior.

Ozone treatment of water‐soluble polymers. III. Ozone degradation of polyacrylamide in water

Abstract: Polyacrylamide (MW 350,000) was ozonized at pH 2 and pH 10 buffer solution. There was little ozonization at pH 2, but at pH 10 the COD and the viscosity of the solution decreased upon ozonization, and a linear relationship existed between the ozone consumed and the number of breaks calculated from the viscosity. This relationship apparently indicated that 45 molecules ozone were consumed for one cleavage of the polymer chain. Such random cleavage was confirmed also by the observation of molecular weight distribution by means of gel filtration chromatography. The amide group decreased scarcely by the ozonization, while a small amount of aldehyde was observed in the ozonized solution. No remarkable change was observed in the IR spectra of the ozonized sample, except for a weak absorption band at 1725 cm−1 which arose from the carbonyl of aldehyde or ketone. Although no variation was observed in the 13C NMR spectra either, a strong absorption peak at 266 nm appeared in the UV spectra of the ozonized solution and increased with the ozonization time. This phenomenon was presumed to be due to the formation of a certain ring structure between the amide group and the small amount of ketone produced in the main chain. However, the details of the ozonization mechanism could not be ascertained.

Fluorescence properties of metoclopramide and its determination in pharmaceutical dosage forms

Abstract: The native fluorescence characteristics of metoclopramide in various solvents and at different pH values were determined qualitatively and quantitatively. Fluorimetric determinations can be performed directly and are based on an intense emission at 360 nm that occurs when the sample is excited at 310 nm following dilution in pH 2.0 buffer solution to a final concentration up to 6 µg ml–1. The detection limit is 3 × 10–2µg ml–1.A comparison is made between the fluorescence behaviour of metoclopramide and the structurally analogous procainamide molecule. Finally, metoclopramide has been converted into its monoacetyl derivative at the primary aromatic amine function. Spectral data confirming the structure are reported. Apart from the second-order excitation shoulder at 275 nm, no significant difference concerning fluorescence behaviour, qualitative or quantitative, between the acetyl derivative and the original molecule is established.

Influence of complexing agents and nature of buffer solution on the chemical durability of glass. Part 2. Effect of EDTA, ethyl alcohol, and sugar in the leach solution

Abstract: The effects of complexing agents such as EDTA, ethyl alcohol, and sugar on the intrinsic chemical durability (using the grain test) of a potash-lead silicate, a binary sodium silicate, and three soda-lime silicate glasses have been studied at different pH values. EDTA in the leach solution favours rapid lead extraction from the glass with a consequent increase in potash extraction. At 50°C the rate of extraction of lead reaches a maximum around pH 11. Ethyl alcohol favours rapid lead extraction at short times due to the formation of the soluble lead-ethyl alcohol complex. However, at long times (more than 2 h at 50°C) a protective layer of insoluble ethyl silicate is formed on the glass surface, and this drastically reduces further lead release from the glass. Sugar in the leach solution accelerates calcium extraction from the soda-lime silicate glasses; the consequent increase in soda and silica extraction is comparatively small.

Solution Properties of Phycocyanin. V. Studies of the Self-association Reaction of Phycocyanin in a pH 5.4 Solution

Abstract: The self-association of phycocyanin in a buffer solution of pH 5.4 with an ionic strength of 0.1 has been studied by sedimentation equilibrium measurements in the temperature range from 5.0 to 25.0 °C. The thermodynamical treatment is also presented. The self-association of phycocyanin molecules proceeds with a decrease in the temperature. The concentration dependence of the apparent weight-average molecular weight of phycocyanin is interpreted in terms of a monomer\ightleftharpoonshexamer equilibrium system. It is clear from the thermodynamic parameters, ΔG0, ΔH0, and ΔS0, that the self-association reaction is spontaneous in the solution of pH 5.4. In the association process, the formation of hydrophobic bonds is suggested by the large positive entropy change accompanying association reaction of phycocyanin molecules.

Technique for Prolonging the Shelf Life of Sulphide Anti-Oxidant Buffer Solution (S.A.O.B.) in Sulphide Determinations

Abstract: A method is described for the preparation of sulphide Anti-Oxidant Buffer Solution (S.A.O.B.). This method prevents the usual rapid oxidation of the solution from taking place.

Separation of coformycin and its related nucleosides

Abstract: A known nucleoside, coformycin and its related substances such as isocoformycin, 2'-deoxycoformycin and formycins present as a mixture of them may be separated from each other when an aqueous solution containing them is chromatographed on a column of a cation-exchanger having partially activated carboxylic groups as the ion-exchange function with using water or a buffer solution as the developing solvent.

Determination of Trace Iron(II) in the Presence of Iron(III)

Abstract: The determination of trace iron(II) is usually interfered by the presence of iron(III) when ortho-phenanthroline colorimetric method is used. In this report a chromogenic reagent which contains ortho-phenanthroline-EDTA mixture has been developed to decrease the interference of ferric ion after adjusting the acidity of sample at 0.1 N by adding the sulfuric acid. The procedure is also simplified by introducing sulfamate buffer solution (pH= 1.5) without adjusting the acidity of sample with sulfuric acid. If iron(III) is not present in the sample, this method is also applicable. The comparative results are exhibited for the present method and the conventional o-phenanthroline method.

Pharmaceutical compositions of a prostaglandin compound for rectal use in treating asthma

Abstract: A pharmaceutical composition for rectal administration containing 11α,15(S)-dihydroxy-20-methoxy-16(S)-methyl-9-oxo-5(cis,13(trans)-prostadienoic acid or a water-soluble salt thereof dissolved or dispersed in a lipophilic or hydrophilic base in the presence or absence of a buffer solution or an aqueous organic amine solution.

Studies on the Formation of Anthocyanin Metal Complex

Abstract: The Fe complex formation of cyanidin-3-glucoside in acetate buffer solution was investigated spectrophotometically. Two different complexes were formed from cyanidin-3-glucoside and , which had the absorption maximum at 543nm in the pH range and at 570nm in the pH range respectively. The molar ratio of the complex formed in the lower pH range was appeared to be 1 : 1, whereas that of the complex formed in the upper pH range was not able to be determined definitely. Among several organic acids examined, citric acid has shown the marked inhibitory effect on the Fe-anthocyanin complex formation.

3'-pyrophosphoric acid-type nucleotides

Abstract: NEW MATERIAL:A compound of formula I (X is nucleoside or its methyl derivative; N is H or hexose, riboflavine, choline or dihydronicotinamido-riboside bonded to 5'-phosphoric acid group of X through its OH group, or nucleoside, nucleotide dinucleotide or their methyl derivatives bonded to the 5'-phosphoric acid of X through its 3'- or 5'-OH group; m is mono-, di- or tri-phosphoric acid group bonded to 5'-position of X; pp is pyrophosphoric acid group bonded to 3'-position of X). EXAMPLE: Cytidine-5'-tri-3'-diphosphoric acid. USE: Medicine. Biochemical reagent for the investigation of phosphoric acid transfer. PROCESS: Reaction of nucleotides II with a pyrophosphoric acid donor in a buffer solution having a pH of 7W10 (containing EDTA-Na, Mg ++ , etc.) in the presence of transferase affords the title compound. COPYRIGHT: (C)1980,JPO&Japio

Novel substrate for determination of enzyme activity

Abstract: NEW MATERIAL:L-γ-Glutamyl-3-carboxy-4-hydroxyanilide of formula, its acid addition salt, alkali metal salt, and amine salt. USE: Substrate for the determination of the activity of γ-GTP. The compound of the formula is reacted with γ-GTP in blood serum in a buffer solution at pH7.5W9.5, and the produced 3-carboxyl-4-hydroxyaniline is coupled with a proper coupler by exidative condensation to obtain a colored substance, which is determined by colorimetry. The high solubility of the compound in water eliminates the necessity of other solubilizing agent. Since the colorimetric determination can be carried out at a wave length of ≥560nm, it is hardly affected by impurities of the specimen. PROCESS: The compound of formula is prepared by reacting an amino-protected glutamic acid anhydride with 3-carboxy-4-hydroxyaniline, and eliminating the protecting group. COPYRIGHT: (C)1980,JPO&Japio

Preparation of urokinase

Abstract: PURPOSE: To make it possible to adsorb and remove colored constituents from crude urokinase effectively, by bringing the aqueous solution of crude urokinase (U) into contact with a strongly basic ion excahnge resin consisting of a polystyrene- divinylbenzene copolymer having quaternary ammonium groups. CONSTITUTION: An aqueous solution of crude urokinase (U), preferably a solution containing U with a specific activity of 10W1,000 IU/mg, obtained by an adsorbent, e.g. silica gel, is brought into contact with a strongly basic anion exchange resin having quaternary ammonium gooups as exchange groups, comprising a polystyrene-divinylbenzene copolymer as a substrate equilibrated with a buffer solution at pH 7W9, preferably 7.5W 8.5, to remove colored constituents and to recover the remaining aqueous solution of U. The amount of the resin is 20W 100ml per 100cc of the aqueous solution containing 1000IU/ml of U. COPYRIGHT: (C)1980,JPO&Japio

Multi-stage concentration and purification of interferon originated from human fibroblast

Abstract: PURPOSE: To prepare an interferon originated from human diploid fibroblast, in high purity, concentration, and yield, by specific multi-stage concentration purification process. CONSTITUTION: An aqueous solution of crude interferon originated from human fibroblast is passed through a column containing a strongly acidic cation exchange material [sulfo(propyl) sephadex, etc.] under acidic conditions to adsorb the interferon. The adsorbed interferon is eluted with a neutral or weak basic buffer solution, and passed through a column containing an insoluble carrier having zinc iminodiacetate (e.g. obtained by bonding iminodiacetic acid to an epoxy-activated sepharose, and converting the free acid to zinc salt). The adsorbed interferon is eluted and recovered with a weak acidic solution. COPYRIGHT: (C)1980,JPO&Japio

Stabilization of urokinase by heating

Abstract: PURPOSE:To inactivate viruses in a urokinase-containing solution, by adjusting the pH of the solution to 6-8 by adding a buffer solution, followed by heating thereof.

Adsorption of Sulphonylureas by Carbon Black from Aqueous Solution

Abstract: The adsorption of sulphonylureas by carbon black from aqueous solution was investigated in detail regarding the hydrophobic interaction The adsorption isotherms obtained were well described with Langmuir equation The adsorbed amount decreased with the increase in pH of buffer solution between 6 and 9, showing that pH had influence on the hydrophobic and hydrophilic balance of the molecule The adsorbed amount increased with the increase in concentration of buffer solution at pH 70, showing that the concentration of buffer solution had influence on water molecules of carbon black surface The decrease in adsorbed amount with addition of urea demonstrated that the adsorption of sulphonylureas proceeded on the hydrophobic interaction The adsorbed amount of sulphonylureas by carbon black decreased with temperature, showing the entropy change of adsorption of sulphonylureas by carbon black from aqueous solution was apparently positive

Method for synthesizing acid blue 104

Abstract: There is described a method for the synthesis of Acid Blue Dye 104 (Color Index. No. 42735) wherein N-benzyl-N-ethyl-toluidinesulfonic acid is reacted with p-diethylaminobenzaldehyde to form leuco Acid Blue Dye 104 which is then isolated and purified with a solvent such as a lower alcohol to provide a very high purity product. The leuco dye is dissolved in a buffer solution of acetic acid and oxalic acid and oxidized by rapidly adding sodium dichromate solution. The Acid Blue Dye is collected and purified to obtain a final product of very high purity and optical transparency.

Use of the penicillanic acid formation reaction for the analysis of penicillins. The quantitative determination of oxacillin

Abstract: A procedure for quantitative determination of oxacillin by means of spectrophotometry is described. The procedure is based on the capacity of penicillins to transform on heating in acid buffer solutions containing copper ions into respective penicillenic acids having specific absorption characteristics in the UV-spectrum region. The amount of oxacillin was estimated by the optical density of the solutions at a wave length of 335 nm corresponding to the absorption maximum of the penicillenic acid of oxacillin. The optimal conditions for the reaction of the penicillenic acid formation, i.e. pH of the buffer solution and the level of the copper ions in it, time and temperature of heating were determined. The data on the comparison of the specificity and reproducibility of the new method with the currently used ones for determination of oxacillin are presented.

Electrophoresis appts. for fractionating materials on a gel - contains two buffer solns. electrically isolated in a container

Abstract: The electrophoresis is carried out on a vertical gel whch is in contact with two buffer solutions, one of which is anodic and the other cathodic, the two being electrically isolated. The two buffer solutions are contained with one container, separated by a layer of a third liq. which is non-miscible, and non-reactive with the other two and acts as a liq. insulator. Various arrangements of the apparatus are possible but in each case a section of the container is separated from the rest in such a way that the lower buffer solution may rise up the separated section to reach virtually the same height as the top of the upper buffer solution thus allowing the electrode to be placed in the lower buffer solution without passing through the two solution above it and also making a route for gases produced to escape. Appts. may be used to fractionate proteins, nucleic acids and in general any substance which needs to be fractionated by electrophoresis of a gel. The appts. is simple and may be used with varying size plates. It can be used for the recovery of the fractionated substances by electrophoretic elution giving a good yield.

Purification of 77aminocephalosporanic acid derivative

Abstract: PURPOSE:To purify the titled compound useful as a raw material for the production of antibacterial agent, etc., economically, in an industrial scale, by adsorbing an aqueous solution containing a specific 7-aminocephalosporanic acid derivative selectively with a particular synthetic adsorbent resin composed of a nonpolar loosely crosslinked polymer, and eluting the adsorbed compound. CONSTITUTION:An aqueous solution containing (A) a 7-aminocephalosporanic acid derivative of formula (X is H, hydroxyl group, acetate group, or nucleophilic residue) is treated with (B) a synthetic adsorbent resin composed of a nonpolar loosely crosslinked polymer selected from a styrenedivinylbenzene crosslinked polymer and an acrylic ester crosslinked polymer. The component (A) adsorbed selectively to the adsorbent resin (B) is eluted with an eluent such as a basic buffer solution, etc. at pH7.0-13.0. Preferably, the adsorbent resin has the mode pore size of 50-1,000Angstrom , a specific surface area of 100-800m /g, and the pore volume of 0.6-1.2cm /g. The adsorption treatment is pref. carried out at pH2.0-6.0.