Boric Acid Buffer Research Articles

Investigation of chemical methods for ozone determination in test chambers

Several chemical methods commonly used for the measurement of ozone concentration in connection with the ozone cracking test of elastomers in test chambers were investigated in detail. The relevant parameters, namely the concentration of potassium iodide, nature and concentration of buffer, aspirating conditions and methods of determining the conversion, were varied and their influence on the results investigated. An absorption solution containing 3% potassium iodide in 0·1 m phosphate buffer was confirmed to be optimal. The boric acid buffer was found to be unsuitable. The titration procedure can be avoided by UV spectrometric measurement of iodine generated. The discrepancy of the results compared with the on-line UV spectrometric ozone determination needs to be investigated further.

Measurement of ozone concentration

The principal methods used to measure ozone concentration are reviewed and experimental comparisons made between chemical methods, with both phosphate and boric acid buffers, UV absorption, and electrochemical methods. The advantages and disadvantages of the methods are considered and recommendations are made for the adoption of a standard reference method for rubber test methods.

The extraction and electrophoretic fractionation of soil humic substances

Humic substances were extracted with six different solvents (acetone, dioxane, ethanol, formic acid plus lithium bromide, sodium hydroxide plus stannous chloride and tris-EDTA boric-acid buffer) from soil under permanent maize, crop rotation, grass (Eragrostis curvula) and natural veld. The extracts were fractionated by column electrophoresis. The fractionation was followed by ultraviolet absorption. It is postulated that the quantity of lowmolecular weight humic substances rather than total humic-substance concentration should give an indication of soil fertility. From the results obtained the relative fertility status of the soil under different vegetational cover were determined. re]19740117

Changes in the conductance of passivated iron thin films during galvanostatic cathodic reduction

The change in the conductance and the potential of passivated films on iron were measured in a neutral borate—boric acid buffer solution (pH 8·39) during galvanostatic cathodic reduction. The conductance increased abruptly at the onset of cathodic current, then remained constant and then increased gradually. The latter two stages corresponded well to the potential plateaus due to the reduction of γ-Fe 2O 3 layer and Fe 3O 4 layer in chronopotentiogram respectively. The initial jump in conductance was attributed to the reduction of the outermost excess oxygen. The resistivities of the γ-Fe 2O 3 layer and Fe 3O 4 layer were estimated from the slope of the conductance—electric charge curves. From the results, it was suggested that the existence of the outermost excess oxygen played an important role in passivity phenomena.

Automated chromatography of aromatic acids, aldehydes and alcohols with an amino acid analyzer

Chromatographic separations of a wide range of aromatic compounds (acids, aldehydes, alcohols) have been performed on a spherical cation-exchange resin with a sodium citrate—boric acid buffer, pH 4.53. The organic compounds were automatically determined in the eluate by measuring their light absorption of 280 mμ or their fluorescence at 315 mμ. The method is applicable to the determination of phenolic metabolites from tyrosine, DOPA, catecholamines or typtophan in biological fluids and tissues.

Re-evaluation of pH and Tonicity of Pharmaceutical Buffers at 37°

Commonly employed isotonic buffer mixtures of pharmaceutical interest were studied at body temperature with emphasis placed on the tonicity and pH of these preparations. Tonicity data interpreted from vapor pressure osmometer data are presented for the official phosphate buffers, boric acid buffer, and Palitzsch buffers. Human serum was also checked at this temperature to validate the accepted base line of 0.90% as being isoosmotic with body fluids. Interesting discrepancies between freezing point depression data and vapor pressure osmometer data are discussed. Reformulated isotonic Palitzsch and boric acid buffers at 37° are presented. A critical assessment of accepting tonicity values at 0° and extrapolating them to body temperature is attempted.

Polagraphic evidence for the formation of a cobalt(I) complex with terpyridine

AC and DC polarographic studies of the reduction of a divalent cobalt complex containing the ligand 2,2′,2′'-terpyridine were undertaken, and evidence is given for the existence of a stable univalent cobalt complex ion in aqueous solution. Diffusion controlled waves were obtained for the Co(terpy) 2 2+ species in boric acid buffer [ph. 7.5] with and without excess ligand. A small pe-wave which is attributed to adsorption is observed. The heterogeneous rate constant and transfer coefficient are evaluated for the main wave.

Zone Electrophoresis of Human Parotid Saliva in Acrylamide Gel

THE zone electrophoresis of human parotid saliva proteins has been carried out with a variety of supporting media, including filter paper, cellulose acetate, agar gel and starch gel, with separations usually of from five to twelve fractions1–8. In a comparative investigation of these media, D'Silva and Ferguson7 obtained their most satisfactory results with a combination of cellulose acetate and starch gel, thereby separating seventeen protein components from the parotid saliva of one subject. The present report concerns an examination of acrylamide gel as another medium for the zone electrophoresis of parotid saliva proteins. Preliminary experiments with acrylamide-gel strips have yielded protein patterns in which twenty or more fractions could be visually distinguished when the electrophoresis was carried out in 0.1 M tris-EDTA–boric acid buffer at pH. 9.0. The tests were conducted on individual collections of parotid saliva from three subjects and on pooled collections of parotid saliva from several subjects. Fig. 1 shows the electrophoresis pattern of a sample of the pooled parotid saliva. Under the conditions of the experiment, more than half the staining components migrated anodically with generally better resolution than is evident for the cathodically-migrating components. Although disk electrophoresis on acrylamide gel has been widely used in investigations of serum proteins, gel strips were used for this investigation of parotid saliva in order to obtain the complete pattern of staining components, migrating both anodically and cathodically, for each electrophoresis run. Gel strips also permit the handling of larger quantities of protein than is feasible with disk electrophoresis, should recovery of particular fractions be desired. Salivary amylase, a troublesome factor in the starch-gel electrophoresis of saliva proteins, does not attack acrylamide gel.

Improved separation of steroid glycols epimeric at C-20 on paper pretreated with boric acid or borate buffers

Abstract Thirteen epimeric pairs of steroid 20,21-glycols, 17α,20-glycols and 17α,20,21-glycerols were chromatographed on paper pretreated with boric acid or borate buffers in the pH range 7·6 to 10. Under these conditions Rt values for individual steroids are determined chiefly by the pH employed, the configuration of the hydroxyl group at C-20 and, in diols, by the site of the hydroxyl group adjacent to C-20. At the pH which affords maximal separation, Rf differences between members of epimeric pairs are notably greater than those obtained on paper treated with water only. The characteristics of a number of nuclear vic-glycols so chromatographed also were determined. The results have been examined in terms of conformational analysis.

Determination of micro-quantities of magnesium.

To 25 ml or less of a neutral sample (containing up to 20 gamma Mg) in a 150ml separating funnel, 10 ml tartrate solution, 10 ml boric-acid buffer and 5 ml Na diethyldithiocarbamate are added and the solution made up to 50 ml. After extracting with 25 ml chloroform and discarding the organic phase the water phase is rinsed with about 10 ml chloroform and the organic phase again discarded. 10 ml of masking agent, 1 ml n-butylamine and 10 ml extracting solution (8-hydroxyquinoline in chloroform) are then added. After shaking and separating the organic phase a knife point of Na2SO4 is added and the extinction of the samples and that of a l0 gamma Mg standard are measured against a simultaneously treated reagent blank at 380 nm. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Starch gel electrophoresis in a discontinous system of buffers.

THE recently developed starch gel electrophoresis has proved to have a resolving power superior to any other type of zone electrophoresis1–4. I have applied this technique to the study of highly purified toxins3, but further work on the separated and eluted fractions of the toxin of Corynebacterium diphtheriae in tissue cultures and in animals indicated that the resolution of these proteins was not completely satisfactory in the buffer (0.03 M boric acid and 0.012 M sodium hydroxide) normally used in this type of zone electrophoresis. A more suitable system was found with a mixture of tris-(hydroxymethyl)-aminomethane-citrate (tris-citrate) used in conjunction with a boric acid buffer. Preliminary results obtained with toxins, enzymes and human sera are briefly reported here.

Downward Shift of p H Caused by Addition of Glucose to Boric Acid Buffer Solutions

Downward Shift of <i>p</i> H Caused by Addition of Glucose to Boric Acid Buffer Solutions

Studies on the kinetics of cell respiration. II. Parallelism between the rate of oxygen consumption by Saccharomyces Wanching and the change in optical rotation of glucose in boric acid buffers

Studies on the kinetics of cell respiration. II. Parallelism between the rate of oxygen consumption by Saccharomyces Wanching and the change in optical rotation of glucose in boric acid buffers

Stabilization of boric acid buffers by aeration

Stabilization of boric acid buffers by aeration