Showing papers on "Buffer solution published in 1973"

Kinetics of the Oxidation of Ascorbic Acid by the Copper (II) Ion in an Acetate Buffer Solution

Abstract: The kinetics of the oxidation of ascorbic acid by the copper(II) ion has been studied spectrophotometrically by a stopped-flow technique. At pH 4–6, the initial rate of the decrease in the monohydroascorbate anion is of the second-order with respect to the total concentration of the copper(II) ion and of the first-order with respect to the concentrations of the monovalent and divalent ions of ascorbic acid:-(d[HA^-]/dt)_t=0=k_1[Cu(II)]_T^2[HA^-]+k_2[Cu(II)]_T^2[A^2-] where HA− and A2− are the monovalent and divalent ions of ascorbic acid respectively. k1, k2, and the activation parameters are obtained as follows: k1=3.1×104, k2=6.1×1010 M−2 s−1, ΔH\eweq=17 kcal/mol, ΔS\eweq=8.3 cal/deg mol, and ΔG\eweq=15 kcal/mol. The EPR signal from the ascorbate radical is not observed in the kinetic run by either a flow technique or a quenching technique. Some discussions of the mechanism of the reaction are given.

Stability of dilute standard solutions of antimony, arsenic, iron and rhenium used in colorimetry

Abstract: A study has been made of the stability of dilute standard solutions of antimony (4 µg ml–1), arsenic (20 µg ml–1), iron (50 µg ml–1) and rhenium (5 µg ml–1) used in colorimetry. The standard elements in these solutions were determined over a period of 2 months by using colorimetric procedures developed in this laboratory and reported previously. Tests were carried out on standard solutions stored in soda-glass, in borosilicate glass and in rigid polyethylene containers.The dilute standard antimony solutions, prepared either by dissolving antimony potassium tartrate in water, or by dissolving elemental antimony in sulphuric acid and diluting the solution with water, were found to be stable (i.e., to deteriorate by less than 2 per cent.) over a period of 50 days. Similar dilute standard antimony solutions containing hydrochloric acid deteriorated rapidly, however.The dilute standard arsenic solutions prepared either by dissolving arsenic(III) oxide in sodium hydroxide solution and then neutralising the solution with hydrochloric acid, or by dissolving disodium hydrogen arsenate heptahydrate in water, were found to be stable. Arsenic(III) in the former standard solution was oxidised slowly by dissolved oxygen, but the total arsenic present in the solution remained unchanged and could be determined by the molybdenum-blue method.An iron(III) standard solution, 0·06 M in hydrochloric acid and prepared from ammonium iron(III) sulphate, was stable for at least 2 months, as was a standard potassium perrhenate solution in a buffer solution of pH 6.Light in the laboratory and the material of the containers did not adversely affect the solutions reported to be stable. Light accelerated the deterioration of the antimony solutions that contained hydrochloric acid, and the material of the containers had a slight effect on the rate of deterioration.

Method for forming polyoxadiazole series resin solution into shaped articles

Abstract: Shaped articles can be produced by subjecting a solution of polyoxadiazole series resin alone or in mixture with at least one inorganic salt in a concentrated sulfuric acid to be coagulated to wet process by using an aqueous solution of sulfuric acid, a lower aliphatic carboxylic acid, a mixture of these acids or a mixture of said acid or said mixture with at least one of inorganic acids and amide compounds as a coagulant and washing the wet-shaped articles obtained by this coagulation with water and then contacting with buffer solution, amine, amide compound or some salt of weak acid or some metal hydroxide.

Orgotein production using a buffer solution containing divalent metal salts

Abstract: THE ISOLATION OF ORGOTEIN FROM AN AQUEOUS SOLUTION OF A MIXTURE OF PROTEINS COMPRISING IT IS FACILITATED BY CONDUCTING THE ISOLATION IN AN AQUEOUS SOLUTION CONTAINING A DIVALENT METAL HAVING AN IONIC STRENGTH OF 0.60 TO 1.00 A., PREFERABLY COPPER, ZINC OR BOTH.

Thermometric assay of some sulphonamides of pharmaceutical importance

Abstract: The thermometric determination of several sulphonamides used in pharmaceutical preparations is described. The sulphonamide is dissolved in the minimum amount of dilute sodium hydroxide solution and the pH adjusted to 8·9 with thymolphthalein as indicator. The solution is then made up to 10 cm3 with an appropriate buffer solution (pH 8·0 or 9·18). In these controlled alkaline conditions, the sulphonamide is titrated directly with silver nitrate solution, the equivalence point being determined thermometrically. The effects of several matrix ingredients in common use in pharmaceutical preparations have been determined. The time of the titration is approximately 1 minute and the accuracy is within ±2 per cent.

Herbicide Analysis by Pulse Polarography-Picloram

Abstract: The herbicide picloram, 4-amino-3,5,6-trichloro-picolinic acid, can be determined at 0.02 ppm, without concentration, by pulse polarography. The effects of pH, ionic strength, and buffer constituents on the catalytic hydrogen process have been studied to optimize conditions for highest sensitivity for picloram. A buffer solution 0.01 M sodium acetate-0.026M acetic acid was used to evaluate the analysis of a natural water system. Errors range from 3–8 % (relative) in the 0.05–0.20 ppm picloram range with precisions of ± 5% (relative) or better. Interferences with 0.1 ppm picloram from 100 ppm Cr(VI) and Zn(II) are severe; neither ion interferes at 1 ppm. Fe(III) interference can be eliminated by masking with EDTA. Mn(II), Cu(II), and Pb(TI) do not interfere at 10 ppm.

フェニルフルオロンと塩化セチルピリジニウムを用いるモリブデン酸およびジルコニウム(iv)の吸光光度定量

Abstract: In the presence of excess cetylpyridinium chloride (CPC) in an acidic solution molybdenic acid(MoO42-) forms a water soluble complex with phenylfluorone, whose color was very stable. The color development of a water soluble reddish brown complex between phenylfluorone and Zr(IV) enhanced by the catalytic action of sodium fluoride, particluary in the coexistence of excess CPC which increased the absorbance of the complex. Their absorption maximum wavelength were at about 540 nm (MoO42-), 560 nm {Zr(IV)} against the reagent blank, and the coloration was stable over the pH range from 1.2 to 1.9 (pH was adjusted with NaCl glycocohol-HCl buffer solution) and pH range from 4.2 to 5.2 (pH was adjusted CH3COONa-CH3COOH buffer solution). A linear calibration curve was obtained for 460 μg MoO42-/10 ml and 07 μg Zr(IV)/10 ml. According to Sandell's expression the sensitivities were 0.01 μg/cm2 of MoO42- and 0.002 μg/cm2 of Zr(IV) for absorbance of 0.001. From the data, the recommended analytical procedures of MoO42-, and Zr(IV) are as follows.A sample containing 460 μg MoO42- is taken in a 10.0 ml measuring flask, and 1.0 ml of 1.0 × 10-2 M CPC solution, 2.0 ml of buffer solution(pH 1.5), and 2.0 ml of 1.0 × 10-3 M phenylfluorone methanolic solution are added. The solution is diluted to 10.0 ml with water, and allowed to stand at 45°C for 30 minutes, the absorbance of phenylfluorone-MoO42--CPC complex is measured at 540 nm against the reagent blank. To the solution of Zr(IV) is added each 1.5 ml of 1.0 × 10-2 M CPC solution, 0.8 ml of 1.0 × 10-2 M sodium fluoride solution, 1.0 ml of 2.0 × 10-3 M methanolic phenylfluorone solution, and 1.5 ml of buffer solution (pH 4.6). After making up to the volume to 10.0 ml and allowing it to stand for 10 minutes, the absorbance is measured at 560 nm against the reagent. The effects of diverse ions on the absorbance of the complex were examined and shown.

Method for obtaining a protein isolate from hydrocarbon assimilating microbial cells

Abstract: A method for obtaining a protein isolate from hydrocarbon assimilating cells, which includes the steps of adding a solution of an inorganic calcium or barium compound to a solution containing protein, which has been isolated from hydrocarbon assimilating microbial cells, and dialyzing the solution prepared by adding the solution of the inorganic calcium or barium compound against a medium selected from the group consisting of water, a buffer solution and a dilute salt solution, whereby a desired protein isolate of high purity is obtained.

The pH Range for the Growth of Sacch. rouxii and Its Utility for Miso Brewing

Abstract: The pH range for the growth of Sacch. rouxii in the environment of a high concentration of sodium chloride was studied and its utility for Miso brewing was also shown in respect to the pH dependence.1. The strains of Sacch. rouxii were classified into three groups on the basis of their pH dependence in the saline medium at 25°C.Group-A: Growth was almost equal in the range of pH3.5-6.5 in the media of 0-3M of NaCl.Group-B: Normal growth was limited in the range of pH 3.5-6.0, 3.5-5.5 in the media of 2M, 3M of NaCl, respectively.Group-C: Normal growth was limited in the range of pH 4.0-5.0 in the media of 3M of NaCl.In general, the range of growth pH was reduced at higher concentrations of sodium chloride and at higher temperature. This tendency was most remarkable in the Group-C.2. In the distribution study, it was revealed that Group-A was most abundant in salty-redMiso of excellent quality and Group-C was the commonest in Soy-mashes.3. By means of plating on three different pH (4.8, 5.5 and 6.0) media containing casamino acid, yeast extract and 18% sodium chloride with McIlvaine's buffer solution, group enumeration was successfully distinguished.4. From the results of brewing trials, Group-A was considered to be the most effective yeast for Miso fermentation.

Oxygen pulping process

Abstract: An improvement in the delignification (pulping) of raw cellulose by treatment with oxygen and an alkaline buffer solution at elevated temperature and pressure, which comprises carrying out the process in an unflooded condition, that is, where contact between the raw cellulose and buffer solution is intermittent, both gaseous and liquid phases being present at all times. Optionally, cupric ion may be present as a catalyst.

The Rates of Hydrolysis of Some Substituted Phenyl 2-Acetamido-2-deoxy-α-and-β-D-glucopyranosides

Abstract: The rates of hydrolysis of some substituted phenyl 2-acetamido-2-deoxy-α-and-β-D-glucopyranosides have been measured in acidic, neutral and alkaline aqueous solutions. In acidic solution, the β-glycosides hydrolyze 2-6 times as fast as the corresponding α-glycosides, and the rates of hydrolysis of the β-glycosides exhibit almost linear ρ-σ relationships (ρ=-0.52 at 61°, -0.54 at 78.2°) whereas those of the α-glycosides show seemingly convex ρ-σ curves, and the tentative calculation on linear relationship shows small ρ values (ρ=-0.16 at 61°, -0.12 at 68.9° and -0.08 at 78.2°). The kinetic parameters for the acid hydrolysis were calculated and discussed in connection with the participation of 2-acetamido group in intramolecular catalysis. The hydrolysis of the glycosides at 120° in neutral buffer solution (pH 6.8) is facilitated by electron-withdrawing substituent (ρ=+0.47 for the α-glycosides, +1.62 for the β-glycosides). The pH-log kobs profile at 120° for the p-chlorophenyl β-glycoside indicates that the glycoside hydrolyzes at a spontaneous hydrolysis rate. The rate of alkaline hydrolysis of the β-glycosides increases with σ (ρ=+1.69 at 100°, +1.65 at 110°), but the α-glycosides are abnormally alkali-stable.

Substituent effects on the condensation of nitrosobenzene with para- and meta-substituted anilines in acetic acid–sodium acetate buffered aqueous ethanol solutions

Abstract: The reaction of nitrosobenzene with meta- and para-substituted anilines has been studied in 94%(v/v) ethanol buffered with acetic acid and sodium acetate solutions A linear Yukawa–Tsuno correlation was obtained (ρ–2·14; correlation coefficient 0·990; r 0·741) ΔΔGP Values for p-nitroaniline and ethyl p-aminobenzoate were obtained It is suggested that two mechanisms can explain the data gathered The kinetic behaviour of the reaction as a function of acetic acid and sodium acetate concentration in the buffer solution was also studied

Pan-mibk 抽出を利用した原子吸光法による水中微量鉄,銅,亜鉛,ニッケル,コバルトの分析

Abstract: A new method for the determination of trace amounts of iron, copper, zinc, nickel and cobalt has been developed by the combination of solvent extraction and atomic absorption spectrophotometry. These metals produce water-insoluble complexes with 1-(2-pyridylazo)-2naphthol (PAN), which were extracted into methyl isobuthyl ketone (MIBK). Although the optimum pH ranges for the complex-formation with PAN were 3-5.5 for iron and 7-10 for other metals, these complexes were able to form by adjusting the pH of solution to 4-5, then raising it to 8-9, and extracted in MIBK simultaneeusly. These complexes were stable in MIBK for ten days. Lineat calibration curves were obtained up to 70 ppb. The coefficients of variation were 5% at 2 ppb for copper, 3% at 5 ppb for iron, and 6% at 5 ppb for zinc, nickel and cobalt.Based on these data, following procedure was presented for the deterrnination of iren, copper, zinc, nickel and cobalt. Four hundred milliliters of the sample solution containing these metals up te 70 ppb are transferred to a 500 ml separatory funnel, and the pH is adjusted to 4-5 by 5 ml of an acetic acid-ammonium acetate buffer solution. After addition of 2 ml of O. O1 mol/l PAN solution, the solution is shaken for 3 minutes. Further, pH is adjusted to 8-9 by 3 ml of 6% ammonia solutien and the solution is shaken for 3 minutes. Then, 20 ml of MIBK are added and metal-PAN complexes are extracted by shaking for 2 minutes. The organic phase is subjected to the atomic absorption measurement following the condition shown in Table 1.The presence of Pb(II), sulfate, thiosulfate, phosphate, pyrophosphate, ehloride, fluoride, or hydrazihe caused no interference to the determination. Even a small amount of cyanide and a large amount of nitrate interfered the determination (Table 5).

2-ヒドロキシ-1-ナフトアルデヒド=2-ベンゾチアゾリルヒドラゾンを用いる微量銅の抽出吸光光度定量

Abstract: A method has been proposed for the spectrophotometric determination of microgram amounts of copper, after extraction of copper(II) from an aqueous solution into chloroform with 2-hydro xy-1-haphtaldehyde 2-benbthiazolylhydrazone(NBH) Various factors such as pH concentration of HNBH vo1ume ratio of two phases, shaking time, diverse ions, etc have been studied, and the optimum conditions for the determination of copper(II) have been established. The ratio of copper to HNBH has er of sample selution S n a 50 ml separatory funnel, and make the volume up to 20 ml with water. djusted to 5.3.v9.5 with acetate buffer solution, and then make the Extract the complex with 10.O m of chloroforme two phases for 5 minutes.After the phases have been sepa- bottle containing sodium sulfate, and the absorbance at 426 nm against the complexwhlch co1d be extracted The extracted coex had an ab- beenE, 60nfirmed to be o ntalnlng up to A linear relationship was found between the concentration of copper and the absorbance. The molar extinction coe cient and the se nstivity for 1o9(Icll)=O OOI were 2 2104 and 2 9 103pg Cu/ma, respectively. Several ions such as silver(1), cobalt(III), mercury(11), titanium('V), thiocyanate, tartrate and citrate interfered with the determination.

Effect of Halide Ions on the Adsorption Prewave of Methylene Blue

Abstract: In the present study, the familiar Langmuir adsorption isotherm is applied to the mixed adsorption of methylene blue in the presence of halide ion. The variation of methylene blue prewave height or AC peak height with halide ion concentration is treated statistically. It is concluded that the decrease in the DC prewave or in the corresponding AC peak height is caused by the mixed adsorption of halide ion. The relative temperature coefficient of AC perk height was found to be 1.04% deg-1 at 25°C in 0.4M KNO3 with acetate buffer solution (pH 4.7).

Kinetics of the oxidation of ascorbic acid by the copper(ii) ion in an acetate buffer solution

Abstract: The kinetics of the oxidation of ascorbic acid by the copper(II) ion has been studied spectrophotometrically by a stopped-flow technique. At pH 4–6, the initial rate of the decrease in the monohydroascorbate anion is of the second-order with respect to the total concentration of the copper(II) ion and of the first-order with respect to the concentrations of the monovalent and divalent ions of ascorbic acid:-(d[HA^-]/dt)_t=0=k_1[Cu(II)]_T^2[HA^-]+k_2[Cu(II)]_T^2[A^2-] where HA− and A2− are the monovalent and divalent ions of ascorbic acid respectively. k1, k2, and the activation parameters are obtained as follows: k1=3.1×104, k2=6.1×1010 M−2 s−1, ΔH\eweq=17 kcal/mol, ΔS\eweq=8.3 cal/deg mol, and ΔG\eweq=15 kcal/mol. The EPR signal from the ascorbate radical is not observed in the kinetic run by either a flow technique or a quenching technique. Some discussions of the mechanism of the reaction are given.