Showing papers on "Buffer solution published in 1975"
TL;DR: Effects show that CO32− decreases the regularity of the atomic arrangement when incorporated in HA, and it is probable that the poor resolution of the X-ray and IR patterns is due, in large part, to small crystal size and internal disorder caused byCO32−.
Abstract: Amorphous calcium phosphate (ACP) was transformed at 25 degrees to hydroxyapatite (HA) in horse and bovine serum; solutions of serum-protein fractions in tris-HC1 buffer (pH 7.4), and pH 7.4 buffers containing from 0.1 to 10 times physiological CO3(2-) concentration. The ACP-to-HA transformation was slower in whole serum and serum fractions than in control buffer solution. The observed adsorption of serum proteins on ACP and HA probably inhibits both the dissolution of the ACP particles and the growth of HA crystals. After 72 h all transformations were complete as determined by X-ray diffraction. The HA crystal dimensions decreased with increasing C03(2-) but the shape, as shown by X-ray linewidths, was relatively constant up to about 4% CO3(2-). At 15% CO3(2-) the crystals were more equiaxial and less needle-like in habit. The radial distribution function (RDF) of HA with 3.7% CO3(2-) is less well resolved than the RDF of HA with ambient CO3(2-) (1.1%). The peaks are less sharp and their amplitude falls more rapidly with increasing atomic separation than for low CO3(2-)-HA. These effects show that CO3(2-) decreases the regularity of the atomic arrangement when incorporated in HA. The rapid decrease, with increasing CO3(2-) content, of the IR splitting of the P-O bending mode of CO3(2-)-HA is attributed to reduced crystal size and possibly to a perturbation of the crystal field due to CO3(2-)-induced lattice distortion. Finally, for bone mineral, it is probable that the poor resolution of the X-ray and IR patterns is due, in large part, to small crystal size and internal disorder caused by CO3(2-).
142 citations
TL;DR: The uptake of quinidine by washed human red blood cells from isotonic buffer solution occurred rapidly and was proportional to the concentration of drug in buffer and the possibility of red cell uptake of drug should be included in any considerations concerning pharmacokinetic aspects of drug action in the body.
Abstract: The uptake of quinidine by washed human red blood cells from isotonic buffer solution (pH 7.4) occurred rapidly and was proportional to the concentration of drug in buffer. A constant red cell/buffer partition ratio of 4.16+/-0.15 s.e. mean was found. 2. Uptake from buffer solution was not affected by temperature or ouabain or by gassing with nitrogen or carbon monoxide and there was no evidence of saturability. Drug in red blood cells was associated largely with the cell contents (94.4+/-1.5% s.e. mean) following partition. 3 Plasma reduced the uptake of quinidine so that a red cell/plasma partition ratio of 0.82+/-0.09 s.e. mean was found. 4 Alteration of plasma binding by dilution of plasma with buffer showed that uptake was proportional to free drug concentration. 5 The possibility of red cell uptake of drug should be included in any considerations concerning pharmacokinetic aspects of drug action in the body.
46 citations
TL;DR: From the studies on the salts effect on the solubility of the tetracycline antibiotics, the drop at more acidic pH value in pH-solubility profiles of CTC-Hcl, DMCT-HCl, and MOTC-H cl was found to be due to the common ion suppression of the solutility product equilibrium.
Abstract: The pH-solubility profiles of tetracycline antibiotics in HCl-sodium acetate buffer solution were obtained at 37°. Solubility vs. pH curves of chlortetracycline hydrochloride (CTC-HCl) passes through a maximum at approximately 2.8 whereas solubility of tetracycline hydrochloride (TC-HCl) increases with decrease in pH. The similar solubility vs. pH curve was also obtained for demethylchlortetracycline hydrochloride (DMCT-HCl) and methacycline (MOTC-HCl). From the studies on the salts effect on the solubility of the tetracycline antibiotics, the drop at more acidic pH value in pH-solubility profiles of CTC-HCl, DMCT-HCl, and MOTC-HCl was found to be due to the common ion suppression of the solubility product equilibrium. The dissolution behavior of the free base and the hydrochloride of tetracyclines was examined in dilute hydrochloric acid solutions, whose pH ranges from 1.2 to 2.1. The results indicated that the free base of CTC, DMCT, and MOTC was more soluble than the corresponding hydrochloride at the gastric pH values (pH 1.2-1.4 for CTC and DMCT and pH 1.2-2.1 for MOTC). On the other hand, TC-HCl exhibited a greater solubility than the base in pH 1.2 since the solubility of TC-HCl was little affected by addition of common ion (Cl-).
21 citations
Patent•
30 Apr 1975
TL;DR: In this article, a method for the recovery of refined α-galactosidase is disclosed, which comprises the steps of bringing an α-GalactoSidase-containing liquid into contact with a weakly acidic cation-exchange resin in the presence of a buffer solution for thereby allowing α-Gase to be selectively adsorbed by said resin, desorbing the adsorsbed α-gase from said resin by use of buffer solution of a type such that at least one of the two factors, concentration and pH, has a higher value than
Abstract: A method for the recovery of refined α-galactosidase is disclosed. This method comprises the steps of bringing an α-galactosidase-containing liquid into contact with a weakly acidic cation-exchange resin in the presence of a buffer solution for thereby allowing α-galactosidase to be selectively adsorbed by said resin, desorbing the adsorbed α-galactosidase from said resin by use of a buffer solution of a type such that at least one of the two factors, concentration and pH, has a higher value than that of the buffer solution used in said adsorption and thereafter recovering the desorbed α-galactosidase.
19 citations
TL;DR: Calibration plots of the change in fluorescence per minute show a good proportionality in the range of 30.8 to 633 U/liter for alkaline phosphatase and in therange of 0.265 to 5.3 King-Armstrong units for acid phosphat enzyme, indicating the usefulness of these methods in the clinical laboratory.
Abstract: We describe enzymatic fluorometric methods for determining activities of serum alkaline phosphatase and of serum acid phosphatase in solution and on silicone rubber pads. 4-Methylumbelliferone phosphate is used as substrate, in either tris(hydroxymethyl)aminomethane or citrate buffer. In solution, the reaction is measured at 37 degrees C in a 3-ml Pyrex cuvette. Measurements on the pads are also made at 37 degrees C, after establishing a stable substrate film by lyophilizing all reagents on the surface of the pads. Only 20 to 30 mul of substrate solution, 50 mul of buffer solution, and 1 to 10 mul of blood are necessary, making a total volume of 51 to 60 mul for each assay. The rate of appearance of the fluorescent 4-methylumbelliferone liberated from 4-methylumbelliferone phosphate by the enzymatic action is measured and equated to enzyme activity. Calibration plots of the change in fluorescence per minute vs. enzyme activity for measurements in solution and on pads show a good proportionality in the range of 30.8 to 633 U/liter for alkaline phosphatase and in the range of 0.265 to 5.3 King-Armstrong units for acid phosphatase, indicating the usefulness of these methods in the clinical laboratory.
15 citations
TL;DR: The results indicate that the influence of F–– on HA solubility cannot be attributed to CaF2 (either as a layer or as discrete crystallites) or to a fluorapatite layer and suggest that the rate of HA dissolution is modified by a rapidly attained F–– equilibrium at the dissolving surface.
Abstract: The solubility of powdered hydroxyapatite (HA) in acidic buffer solution (pH 4.65) was reduced by 71% by adding sufficient fluoride (F––; either by previously treating the HA with NaF solution or by introducing NaF at the start of the dissolution) to replace approximately 25% of all surface unit cell OH–– ions. The same amount of F–– was less effective if added as NaF after the start of the dissolution. Addition of CaF2 had no effect. The results indicate that the influence of F–– on HA solubility cannot be attributed to CaF2 (either as a layer or as discrete crystallites) or to a fluorapatite layer and suggest that the rate of HA dissolution is modified by a rapidly attained F–– equilibrium at the dissolving surface.
10 citations
Patent•
12 Aug 1975
TL;DR: In this paper, an aqueous solution containing β-amylase obtained by extraction of β-AMylase-containing plants with water or a buffer solution can be efficiently concentrated and purified at a high temperature by membrane separation.
Abstract: An aqueous solution containing β-amylase obtained by extraction of β-amylase-containing plants with water or a buffer solution can be efficiently concentrated and purified at a high temperature by membrane separation without inactivation of β-amylase and putrefaction of the aqueous solution by incorporating a divalent or trivalent metal ion into the aqueous solution and adjusting the pH of the aqueous solution to about 4.5 to 8.0.
9 citations
TL;DR: In this paper, a rapid procedure for the routine determination of nanogram amounts of silver in rocks is described, where the silver is separated by extraction as the dithizonate into xylene and back-extracted into dilute hydrochloric acid.
9 citations
TL;DR: In this article, the partition constants, minimal solubilities and dissociation equilibrium constants of 8-hydroxyquinoline and 5-chloro-8-hydrox-quinoline were determined for the system n-octanol buffer solution at 25° C and 0.01M ionic strength.
Abstract: The partition constants, minimal solubilities and dissociation equilibrium constants of 8-hydroxyquinoline and 5-chloro-8-hydroxy-quinoline and the partition constant of 5-nitro-8-hydroxyquinoline have been determined for the system n-octanol—aqueous buffer solution at 25° C and 0.01M ionic strength. The effect of substituent and organic solvent on these parameters have been discussed. The thermodynamic dissociation constants, obtained from spectrophotometric measurements, are: 8-hydroxyquinoline,pK1= 4.94 ± 0.01,pK2= 9.82 ± 0.01; 5-chloro-8-hydroxyquinoline,pK1 = 3.79 ± 0.01,pK2 = 9.29 ± 0.01.
8 citations
TL;DR: In this paper, a method for the determination of orotic acid in milk was proposed, and the effect of the presence of surface-active substances like proteins was investigated, which permits the accurate determination of 4-1000 μg/g of OO in milk.
Abstract: The polarographic behavior of orotic acid at the dropping mercury electrode was studied in the Britton-Robinson buffer solution; it was found to be a complex function of the pH. Three polarographic waves were observed over the pH range from 2 to 12. In the 1M HClO4 electrolyte, orotic acid showed a very well-defined, diffusion-controlled, two-electron polarographic reduction wave which enabled us to determine orotic acid polarographically. A polarographic method for the determination of orotic acid in milk was proposed, and the effect of the presence of surface-active substances like proteins was investigated. The proposed method is very simple and rapid, and permits the accurate determination of 4–1000 μg/g of orotic acid in milk.
6 citations
01 May 1975
TL;DR: A magnetic field applied perpendicular to the electric field that induces electrophoresis has a direct effect on the conductivity of the buffer solution and on the ionic fluidity through saturated polymeric electrophoretic strips.
Abstract: A magnetic field, applied perpendicular to the electric field that induces electrophoresis, has a direct effect on the conductivity of the buffer solution and on the ionic fluidity through saturated polymeric electrophoretic strips. Magnetoelectrophoresis of blood serum yields different patterns of globulins as compared with ordinary electrophoresis. Changes in the separation velocities amount to 15–18% for magnetic field intensities in the range 0·8.−1 T.
TL;DR: In this paper, an elastin fraction was obtained during the hydrolysis of bovine ligamentum nuchae and stored for over three years at about 3°C and microscopic examination showed that the texture of the gel depended on the protein concentration, pH and the ionic strength of the buffer solution used to cause swelling.