Showing papers on "Buffer solution published in 1977"

2-Mercaptobenzothiazole Supported on Silica Gel for the Chromatographic Concentration of Cadmium, Copper, Lead, and Zinc in Natural Water Samples

Abstract: The preparation and characteristics of 2-mercaptobenzothiazole supported on silica gel (MBT–SG), and its application to the preconcentration and determination of cadmium, copper, lead, and zinc in natural water samples are described. The MBT–SG was prepared by impregnating silica gel with MBT in a dioxane–methyl acetate solvent mixture, drying, washing with deionized water, and finally drying. The chelating capacity of the material was 0.01 meq. Cu/g. Cadmium, copper, lead, and zinc were quantitatively retained on the MBT–SG at pH values of 4.8, 2.5, 4.8, and 6.5 for an aqueous solution, and at pH values of 4.8, 2.8, 4.8, and 6.5 for sea water. A column made of the material provided quantitative recovery of these metals from natural water samples at higher flow rates (2–5 1/h) than other chelating resins, e. g., chelex 100. Cadmium was eluted with hydrochloric acid (1 : 99), copper and lead with acetone–hydrochloric acid mixture (9 : 1), and zinc with an acetate–hydrochloric acid buffer solution (pH 4.0)....

Effects of metal ions and flavonoids on the oxidation of ascorbic acid.

Abstract: Effects of metal ions and flavonoids on the oxidatio of ascorbic acid (I) have been investigated polarographically in the acetate buffer solution of pH 5.4. since I gives a diffusion-controlled anodic wave due to a two-electron oxidation to form dehydroascorbic acid, the rate of the oxidation of I can be followed by measuring the change in the limiting current of I with time. The rate of the oxidation of I was enhanced by the presence of some metal ions. Among them, the effect of copper (II) was especially pronounced. Such the fact can be explained on the basis of the formation of a coordinative linkage between metal and ascorbate ions and the reducibility of metal ions. Contrary to this, flavonoids exhibited an inhibition effect on the copper (II)-catalyzed oxidation of I. The effect became more marked in the order of 3-hydroxyflavone

Thermochromic composition, method of making, and use

Abstract: PH indicator composition has controlled change of color at a selected sub-freezing temperature. The composition comprises at least one pH indicator, a buffer solution containing at least one inorganic ion in solution and a control agent or a precursor of a control agent. The buffer solution has a pH capable of changing when the temperature of the buffer solution is lowered to below freezing. The control agent is capable of effecting a change in ionic strength and proton composition of the frozen pH indicator composition to thereby control the temperature at which the color change occurs. A method of using the composition comprises lowering the temperature from a first temperature above freezing to a second temperature at which the pH indicator composition is in a substantially frozen state. The composition is particularly useful in a color change thermometer.

PH monitor with automatic buffer standardization

Abstract: An apparatus for monitoring the pH of a sample source is disclosed. The apparatus has a sample chamber to which fluid is fed from the sample source for pH monitoring. An automatic rinse and buffer standardization system automatically, periodically standardizes the apparatus against a buffer solution of known pH.

Influence of fixation and buffer treatment on the release of enzymes from the plasma membrane.

Abstract: 1. Pretreatment of frozen cryostat sections with formaldehyde or calcium ions inhibits diffusion of the plasma membrane enzymes 5′-nucleotidase, ATP-ase and alkaline phosphatase during incubation. 2. Treatment of fixed sections with different kinds of buffer at 37°C induces diffusion of enzyme activity from the plasma membrane to other sites of the section and into the incubation medium. This buffer influence depends on temperature: at 4°C only a slight diffusion occurs. Addition of phospholipase C, digitonin or taurocholate to the buffer opposes the buffer effect. 3. Pretreatment of frozen cryostat sections with a mixture of equal parts of chloroform and acetone gives a good fixation of the plasma membrane enzymes 5′-nucleotidase, ATP-ase, alkaline phosphatase and leucyl-β-naphthylamidase. During this treatment the different kinds of lipids present in the membrane are extracted equally. After this fixation buffer treatment does not cause a visible diffusion of enzyme activity in the section. Only a slight diffusion (1 till 7 percent) into the buffer solution takes place. 4. The mentioned treatments open up possibilities to get insight into the membrane anchorage of plasma membrane enzymes.

Effect of cathodic potential on the electrochemical synthesis of optically active amino-acids

Abstract: In acetate buffer solution, in the presence of strychnine, the electroreduction of phenylglyoxylic acid oxime leads to optically active phenylglycine, the absolute configuration of which depends on the cathodic potential used.

Method and apparatus for the continuous determination of the concentration of an enzyme substrate

Abstract: Enzyme substrates in aqueous liquids are continuously measured by introducing a sample containing the substrate to be determined into a current of buffer solution, reacting the substrate on an immobilized enzyme and measuring, in a measurement chamber, a physical change in the solution brought about by the reaction, wherein a current of buffer solution containing the sample to be determined is passed alternatingly (i) directly through the measurement chamber with the production of a reference signal and (ii) first over the immobilized enzyme and thereafter through the measurement chamber with the production of a measurement signal, and relating the reference signal to the measurement signal to indicate the enzyme substrate initially present.

Characterization of meningococcal polysaccharides by optical mixing spectroscopy. II. Effects of temperature, EDTA, and ionic strength on aggregation of group C polysaccharides in solution.

Abstract: We have studied the effects of temperature, EDTA, and ionic strength on C-polysaccharides in solution by examining the details of the time-correlation function using a 96-channel single-clipped photon correlation spectrometer. Our linewidth results have shown that the C-polysaccharides in buffer solution form aggregates of very broad distributions. Thus, fractionation by gel-filtration chromatography is only mildly effective. Although the aggregate sizes seem to remain relatively constant from 4 to 25°C, a fraction of those aggregates break up to form smaller fragments or monomers at higher temperatures. However, the dissolution-association process is quite slow and takes days even at room temperatures before the equilibrium is reached. We have also shown that by adding an excess amoutn of EDTA, the aggregates can be broken up. Again the dramatic changes occur only at short delay times suggesting that a protion of the larger aggregates remains. Finally, the amount and size of aggregates depend upon the ionic strength which exhibit a maximum ΓT/sin2 (θ/2) around 0.1–0.2 M KCl. If the activities of polysaccharides in solution depend upon molecular size, the standard techniques such as gel-permeation chromatography and ultracentrifugation cannot properly characterize the detailed size distribution. Quasielastic laser light scattering can provide us with a qualitative model. The quantitative details must necessarily await more extensive investigations using a combination of the techniques and better fractionation procedures in an appropriate buffer solution.

Pressure Effect on the Base Hydrolysis Rate of [Co(NH3)5Cl]2+ in a Carbonate Buffer

Abstract: The pressure effect on the base hydrolysis reaction rate of [Co(NH3)5Cl]2+ in a 0.0133 M Na2CO3–0.0200 M NaHCO3 buffer solution was measured up to 1500 kg cm−2 (M=mol dm−3). The activation volume (ΔV\eweq) was found to be 33.4 ml mol−1. This value is consistent with that expected from the Dcb mechanism.

Standard pH values for the potassium hydrogen phthalate reference buffer solution from 0 to 60°C

Abstract: where mKC\ was 0.015, 0.01, or 0.005 mol kg" , from which values of the acidity function p(aHyci) were derived. The pH convention defines yCi in the range of ionic strengths 0 to 0.1 mol kg" 1 and permits conventional values of paH to be obtained. According to NBS procedures, paH for selected reference solutions is identified with the standard pH(S) in the operational definition of pH. The new values, given in terms of the thermodynamic temperature (T) by

Stabilized nadh aqueous solution

Abstract: PURPOSE: To prepare a useful and stable aqueous solution of reduced βnicotinamide-adenine-dinucleotide (NADH) by using an buffer solution containing a carbonate as a buffer salt. COPYRIGHT: (C)1978,JPO&Japio

Behaviors of c. i. reactive blue 19 in aqueous solution

Abstract: C. I. Reactive Blue 19 (applied in the vinylsulfonyl-form), one of the sulfatoethylsulfonyl reactive dyes, was treated in buffer solution of pH range 7.1-10.2. The resulting ether-form was investigated on the amounts of formation, the stability and the dyeability.The following results were obtained:1) The maximum yield of formation of the ether-form from the vinylsulfonyl-form was 37.15% at 60°C, 18.55% at 80°C.2) The ether-form was very stable in neutral solution at 60°C but considerably decomposed at 80°C even in pH 7.19.3) The ether-form did not fix for degummed silk in acidic condition but did in neutral or alkaline solution and then the maximum fixation was about 30% at 80°C.4) When the ether-form was treated in buffer solution, the formation of the vinylsulfonyl-form was observed. In addition, the ether-form exhibited a considerable fixation for degummed silk as mentioned above. For these reasons, it seemed that the following reaction was occurred both in aqueous solution and on silk fber: Ether-form _??_ Vinylsulfonyl-form+Hydroxyethylsulfonyl-form From these results it was considered that the existence of the ether-form was negligible in the silk dyeing under the following condition: Temperature: 80°C, pH: 7-9, Time: 1-2hr

Heats of mixing of polyriboadenylic acid and polyribouridylic acid in aqueous NaCl solution

Abstract: The heats of mixing of polyriboadenylic acid (Poly A) and polyribouridylic acid (Poly U) in various proportions by changing the mole ratio n = [Poly U]/[Poly A] in 0,001, 0,1, and 0,5 molar NaCl solutions containing 0,1 molar tris-HCl buffer solution were measured. Constant values for the heats of mixing of the (Poly A+n Poly U) system are found for n ≤ 1 and n ≥ 2. From the results of UV and CD spectra, it may be considered that the mixing of Poly A and n (Poly U) leads to the formation of Poly(A+U) for n ≤ 1, and to that of Poly(A+2U) for n ≥ 2, even at [NaCl] = 0,001 mol/l. The enthalpies of formation of Poly(A+U) and that of Poly(A+2U) depend on the concentration of NaCl. This dependence may be attributed to the differences in conformation of Poly(A+U) in NaCl solution.

Spectrophotometric determination of malonate with diazotised 4-nitroaniline

Abstract: When malonate is treated with diazotised 4-nitroaniline for 3 h at 25 °C in acetate buffer solution (pH 5.2) and then with 5 N hydrochloric acid, an intense and stable orange dye is produced with a large absorbance maximum at about 445 nm. Malonate can be determined in this way in the range from about 5 to 50 µg (0.05–0.5 µmol ml–1). Oxaloacetate, acetoacetate and ascorbate, which produce a similar colour under the same conditions and thus hamper the determination of malonate, are removed by prior immersion of the sample in boiling water and by the addition of sodium nitrite.

Stabilized composition containing carpronium chloride

Abstract: PURPOSE:To provide a low-cost, high-safety title composition free from physiologically active compound, by adding a buffer solution containing malic acid, to a carpronium chloride composition. CONSTITUTION:The pH of a carpronium composition (e.g. hair lotion, hair cream, etc.) is adjusted between about 4 and 6 by adding a buffer solution containing malic acid (e.g. sodium malate-malic acid buffer solution). The residual amount of the carpronium chloride in the above prepared composition is more than about 90% after 3-year storage at room temperature.

Amino acid analyzer

Abstract: PURPOSE:To provide an NH3 adsorption column between a buffer tank and pump and regenerate the column at every analysis, thereby eliminating the floating and disorder of the base line occurring in the NH3 in buffer solution, automating high-sensitivity analysis and performing the analysis continuously.

Synthesis of peptides

Abstract: PURPOSE:To prepare a polypeptide in high yield by reacting a specific amino acid or amino-terminated peptide with a specific amino acid or carbonyl-terminated peptide in a buffer solution in the presence of a Mtallo proteinase and a proteinase inhibitor.

Effect of cathodic potential on the electrochemical synthesis of optically active amino-acids

Abstract: In acetate buffer solution, in the presence of strychnine, the electroreduction of phenylglyoxylic acid oxime leads to optically active phenylglycine, the absolute configuration of which depends on the cathodic potential used.