scholarly journals The preparation of α-oxo acid derivatives suitable for specific-radioactivity determination

1970 ◽  
Vol 120 (1) ◽  
pp. 171-175 ◽  
Author(s):  
J. Mowbray ◽  
J. H. Ottaway
Keyword(s):  
Hydrochloric Acid ◽  
Initial Rate ◽  
Specific Radioactivity ◽  
Optimum Conditions ◽  
Quinoxaline Derivatives ◽  
Absorption Of Light ◽  
Rate Of Reaction ◽  
Chemical Determination ◽  
Layer Chromatography

1. Conditions favouring the condensation of o-phenylenediamine with α-oxo acids to form substituted quinoxalines have been investigated. The best yields (85–100%) are obtained by incubation of the reagents in 2m-hydrochloric acid. Substitution of acetic acid for hydrochloric acid, or of halogen-substituted 1,2-diaminobenzenes for phenylenediamine, increases the initial rate of reaction, but not the yield of quinoxalines. 2. The quinoxaline derivatives are insoluble in water and can be readily purified. They are very suitable for determination of the specific radioactivities of radioactively labelled α-oxo acids because they are colourless, soluble in dioxan-based scintillators, and their strong absorption of u.v. light facilitates their chemical determination. As little as 1 nmol can be accurately determined by means of the blue fluorescence produced by absorption of light at 340–360nm. 3. Optimum conditions for preparation, purification and separation by paper and thin-layer chromatography are described.

An Improved Periodic Acid Fuchsin Sulfite Staining Method for Evaluation of Glycoproteins

1958 ◽  
Vol 4 (6) ◽  
pp. 476-483 ◽  
Author(s):  
Warren F McGuckin ◽  
Bernard F McKenzie
Keyword(s):  
Hydrochloric Acid ◽  
Periodic Acid ◽  
Distribution Patterns ◽  
Paper Electrophoresis ◽  
Acid Control ◽  
Chemical Determination ◽  
Disease Entities ◽  
The Individual

Abstract Modification of the Köiw and Grönwall procedure for the staining of glycoproteins separated by paper electrophoresis has adapted this method to papers of the Whatman 3MM class, with achievement of results comparable to those reported by direct chemical determination of hexose in the individual protein fractions. Preliminary concentration of specimen fluids was achieved by ultrafiltration through collodion sacks. A preliminary wash of the oven-dried paper strips with 95 per cent ethanol was found essential to clear the paper of buffer salts and insure that the pH in the oxidation procedure remained in the 3.0-3.5 range. Close control of the reagent composition and timing of each step were found necessary. Inclusion of 40 per cent ethanol in the oxidation bath and immersion of dry strips were required to insure rapid penetration of the periodic acid. Control of the oxidation procedure at 20 ± 0.5° for 12 minutes was of prime necessity to maintain a low background color. Also, the concentrations of hydrochloric acid in the dye bath and in the wash solutions were found to affect the quality of the final stain. The ethanol wash served to remove residual sulfite and hydrochloric acid and stabilize the color. The new method has been applied to the analysis of several body fluids of normal persons and patients with certain disease entities, and satisfactory glycoprotein distribution patterns have been obtained.

Glucocorticoids directly affect spectrophotometry of bilirubin in amniotic fluid.

1984 ◽  
Vol 30 (5) ◽  
pp. 677-680
Author(s):  
A Milwidsky ◽  
S Yagel ◽  
M Chaouat ◽  
M Mayer
Keyword(s):  
Amniotic Fluid ◽  
Binding Sites ◽  
Time Dependent ◽  
Hemolytic Disease ◽  
Low Concentrations ◽  
Chemical Determination ◽  
Cautious Interpretation ◽  
Layer Chromatography

Abstract Dexamethasone or prednisolone, added in vitro to bilirubin-containing amniotic fluid, produces a time-dependent decrease in the 450-nm absorbance of the pigment. Neither the chemical determination of bilirubin in amniotic fluid nor the lecithin/sphingomyelin ratio as determined by thin-layer chromatography is affected by these glucocorticoids. The effect probably is not a result of displacement of bilirubin from its binding sites on albumin, because the absorbance of a solution of crystalline bilirubin at 450 nm is unaffected by added bovine serum albumin. Light scattering of amniotic fluid increases slightly when dexamethasone is added, whether or not low concentrations of bilirubin (less than 1.6 mumol/L) are present. Thus the effect on absorbance evidently is not ascribable to supersaturation and formation of a colloidal sol of bilirubin particles. This direct interference of glucocorticoids with the spectrophotometry of bilirubin in amniotic fluid prompts cautious interpretation of such data as an index to the severity of hemolytic disease of the fetus, specifically in cases of Rhesus-isoimmunization that are being treated with glucocorticoids.

Determination of low concentrations of dibenzyl sulfoxide in aqueous solutions

1979 ◽  
Vol 44 (6) ◽  
pp. 1908-1917 ◽  
Author(s):  
František Vláčil ◽  
Huynh Dang Khanh
Keyword(s):  
Standard Deviation ◽  
Hydrochloric Acid ◽  
Low Flow ◽  
Optimum Conditions ◽  
Hydrochloric Acid Medium ◽  
Low Concentrations ◽  
Limit Of Determination ◽  
Relative Standard ◽  
Basic Anion

A spectrophotometric method was developed for the determination of low concentrations of sulfoxide in water, relying on the formation of a leuco-compound from the reaction of L-tryptophan with p-dimethylaminobenzaldehyde and its oxidation by sulfoxide in hydrochloric acid medium. The optimum conditions for the determination were found by using the simplex method. The calibration curve, measured at 620 nm, is linear up to the sulfoxide concentration 7.5 . 10-5 mol l-1 (i.e. 17.3 ppm), the limit of determination is 0.1 ppm, the reproducibility, expressed as the relative standard deviation (for n = 6) is 3-4%. Oxidants interfere with the determination. Nitrates can be removed by means of a strongly basic anion exchanger in the chloride form. Mixture water-acetone (6 + 1) passing with a low flow rate should be applied to the elution of the partly sorbed sulfoxide.

Reflectance spectroscopic determination of cobalt, nickel, and copper with pyridine-2-aldehyde-2-quinolylhydrazone

1968 ◽  
Vol 46 (2) ◽  
pp. 167-173 ◽  
Author(s):  
R. W. Frei ◽  
R. Liiva ◽  
D. E. Ryan
Keyword(s):  
Diffuse Reflectance ◽  
Diffuse Reflectance Spectroscopy ◽  
Reflectance Spectroscopy ◽  
Good Reproducibility ◽  
Optimum Conditions ◽  
Cobalt Nickel ◽  
Nickel Cobalt ◽  
Cellulose Layers ◽  
Layer Chromatography

Nickel, cobalt, and copper are separated from interfering metals by thin-layer chromatography on silica gel and cellulose layers. The metals are sprayed with pyridine-2-aldehyde-2-quinolylhydrazone solution and determined by diffuse reflectance spectroscopy. Under optimum conditions, 0.01 µg per spot can be determined easily and with good reproducibility.

Kinetic Analysis of Rubber Halides

1950 ◽  
Vol 23 (2) ◽  
pp. 447-456 ◽  
Author(s):  
G. Salomon ◽  
C. Koningsberger ◽  
A. J. Ultée
Keyword(s):  
Hydrochloric Acid ◽  
Natural Rubber ◽  
Kinetic Analysis ◽  
Reaction Kinetics ◽  
Organic Halide ◽  
Organic Bases ◽  
Rate Of Reaction ◽  
Closed Systems

Abstract A correlation is established between the structure of an organic halide and its rate of reaction with a number of organic bases. Analysis by reaction kinetics, based on this correlation, is applied to the following problems. (1) Estimation of the allylic fraction in the chlorination and bromination of natural rubber. (2) Differentiation between a dichloride and a polychloride from natural rubber. (3) Determination of an equilibrium between natural rubber and hydrochloric acid at 130° C in closed systems. (4) Identification of tertiary chlorides and bromides in natural rubber and allied polymers.

Determination of molybdenum in rocks by atomic absorption spectrometry with electrothermal atomization after its separation with α-benzoinoxime

1984 ◽  
Vol 49 (2) ◽  
pp. 370-377 ◽  
Author(s):  
Dalibor Kolčava ◽  
Jan Janáček
Keyword(s):  
Hydrochloric Acid ◽  
Atomic Absorption Spectrometry ◽  
Atomic Absorption ◽  
Tartaric Acid ◽  
Graphite Furnace ◽  
Accurate Determination ◽  
Absorption Spectrometry ◽  
Electrothermal Atomization ◽  
Optimum Conditions

A method has been worked out for a sensitive and accurate determination of molybdenum in rocks in contents of the order of 10-1 g/t. The sample is decomposed with acids and molybdenum is separated from practically all other elements by extraction with α-benzoinoxime from solution of 1.5 M hydrochloric acid and 0.13 M tartaric acid into chloroform, and determined in the extract by AAS with electrothermal atomization. The quantitativeness of the extraction has been examined and the optimum conditions for the determination in a graphite furnace have been established. The effects of chloroform and of the graphite atomizer on the signal of molybdenum have been investigated, and the accuracy of the method has been tested on GXR geochemical standards.

scholarly journals Determination of the half-life and the quantum yield of ZnO semiconductor photocatalyst in humic acid

2018 ◽  
Author(s):  
Rahadian Zainul
Keyword(s):  
Humic Acid ◽  
Quantum Yield ◽  
Half Life ◽  
Optimum Conditions ◽  
Constant Rate ◽  
Rate Of Reaction ◽  
Kinetics Of ◽  
Zno Semiconductor ◽  
Semiconductor Photocatalyst

This research aim to investigate kinetics of humic acid photo-transformation. This study was done under some optimum conditions: lighting time of 2 hours, using Hg lamp of low pressure ( λ = 254 nm), humic acid of 100 ppm and pH=9.2. it was disclosed that 97.51 % of humic acid transformed into minerals product which involved the first orde reaction, 38.4 minute half-life, the constant rate of reaction is 0.02 minutes-1 and the quantum rendement of 0.115 molecules per photons.

scholarly journals Validated spectophotometric methods for the assay of cinitapride hydrogen tartrate in pharmaceuticals

2013 ◽  
Vol 19 (2) ◽  
pp. 303-311
Author(s):  
K.V.V. Satyanarayana ◽  
Rao Nageswara
Keyword(s):  
Hydrochloric Acid ◽  
Alkaline Medium ◽  
Sodium Nitrite ◽  
Azo Dyes ◽  
Molar Absorptivity ◽  
Optimum Conditions ◽  
Pharmaceutical Tablets ◽  
Spectrophotometric Methods ◽  
Ich Guidelines

Three simple, selective and rapid spectrophotometric methods have been established for the determination of cinitapride hydrogen tartrate (CHT) in pharmaceutical tablets. The proposed methods are based on the diazotization of CHT with sodium nitrite and hydrochloric acid, followed by coupling with resorcinol, 1-benzoylacetone and 8-hydroxyquinoline in alkaline medium for methods A, B and C respectively. The formed azo dyes are measured at 442, 465 and 552 nm for methods A, B and C respectively. The parameters that affect the reaction were carefully optimized. Under optimum conditions, Beer?s law is obeyed over the ranges 2.0-32.0, 1.0-24.0 and 1.0-20.0 ?g. mL-1 for methods A, B, and C, respectively. The calculated molar absorptivity values are 1.2853 x104, 1.9624 x104 and 3.92 x104 L.mol-1.cm-1 for methods A, B and C, respectively. The results of the proposed procedures were validated statistically according to ICH guidelines. The proposed methods were successfully applied to the determination of CHT in Cintapro tablets without interference from common excipients encountered.

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