Criteria Of Purity Research Articles

Spectrum of Delayed Fluorescence in Phenanthrene Vapour: a Criterion of Purity

IN addition to the normal fluorescence emission with a decay constant of ∼ 109 sec.−1, a slow component with a decay constant of ∼ 103 sec.−1 has been detected by Dikun in the luminescence of phenanthrene vapour1. On the grounds that the spectra of both components are identical, Williams2 has attributed this delay to the reversible formation of an excited dimer, from normal and electronically excited molecules, which has a life-time of the order of a millisecond.

Studies on the intracellular localization of anterior pituitary hormones by means of differential centrifugation.

Journal Article STUDIES ON THE INTRACELLULAR LOCALIZATION OF ANTERIOR PITUITARY HORMONES BY MEANS OF DIFFERENTIAL CENTRIFUGATION Get access J. H. U. BROWN, J. H. U. BROWN 1Department of Physiology, Emory University Atlanta, Georgia Department of Pharmacology and Therapeutics, University of Manitoba Winnepeg, Canada Search for other works by this author on: Oxford Academic Google Scholar FRANK S. LABELLA, FRANK S. LABELLA 1Department of Physiology, Emory University Atlanta, Georgia Department of Pharmacology and Therapeutics, University of Manitoba Winnepeg, Canada Search for other works by this author on: Oxford Academic Google Scholar FRODE ULVEDAL FRODE ULVEDAL 1Department of Physiology, Emory University Atlanta, Georgia Department of Pharmacology and Therapeutics, University of Manitoba Winnepeg, Canada Search for other works by this author on: Oxford Academic Google Scholar Endocrinology, Volume 66, Issue 1, 1 January 1960, Pages 1–12, https://doi.org/10.1210/endo-66-1-1 Published: 01 January 1960 Article history Received: 02 September 1958 Published: 01 January 1960

Studies on Haematoxylin and Haematein, the Colouring Principles of Logwood: I–Absorption Spectra of Pure Compounds in Various Solvents and a Spectrophotometric Method of Analysis for Haematoxylin and Haematein

A modified method is described for the preparation from logwood extracts of pure haematoxylin. The criterion of purity is the ultraviolet absorption spectrum in methanol. In most solvents with low ultraviolet absorption, haematoxylin is either too insoluble or too susceptible to oxidation for suitable spectra to be obtained without special precautions.The salient features of the visible and ultraviolet absorption spectra of haematein (about 10 mg. / litre) in six solvents are given. In most of these haematein is eventually oxidised to give a product with a characteristically different spectrum. Solutions in dimethylformamide containing 1 % of a phosphate–citric acid buffer are sufficiently stable for the haematein content to be determined by reference to the peak at 440 mμ. instead of the previously used peak at 280 mμ., which is shown to be unsuitable.Examples of the application of the analytical method to commercial materials are given.

Ricinelaidic acid and methyl ricinelaidate. Their preparation and determination by infrared spectroscopy

SummaryImproved methods for the preparation of ricinelaidic acid and methyl ricinelaidate are described. The methods depend upon the elaidinization of methyl ricinoleate with a relatively small quantity of a nitrite‐nitric acid solution, fractional crystallization of the methyl ricinelaidate, and its subsequent hydrolysis to ricinelaidic acid. The infrared spectra of these two compounds are presented, and bands arising from a deformation of the C−H about thetrans C=C group are discussed. Absorptivity values for this band in chlorform and in carbon disulfide solutions are given as additional criteria of purity of ricinelaidic acid and its methyl ester. The infrared absorption procedure for the quantitative determination of isolatedtrans ethylenic bond was applied to the determination of both ricinelaidic acid and methyl ricinelaidate. Details of specific procedures for the determination of each compound are given with the equations necessary for their calculation. Use of these methods is illustrated with the analysis of elaidinization mixtures. The repeatability and accuracy obtaineble are given. A value is reported for the methyl ricinoleate—methyl ricinelaidate equilibrium and the mechanism of the reaction is discussed briefly.

Purification of folic acid.

Various purification procedures for folic acid were investigated. The criteria of purity were a negative Bratton-Marshall test and the absence of fluorescent spots on paper chromatograms. Since no method provided a pure product, a procedure consisting of cellulose column chromatography followed by filtration through charcoal was developed.

Ultraviolet criteria for monoaromaticity

Consideration of the ultraviolet absorption spectra (2000–4000 Å) of monoaromatic hydrocarbons of a wide range of structure and substitution type permits the enunciation of three general criteria that the spectrum of a substance or a mixture of substances must satisfy in order that it may be classified as a spectroscopically pure monoaromatic hydrocarbon. The bases for the formulation of these criteria of purity are described and discussed and the mode of application is exemplified.

Studies on the antigenicity of beta- and alpha-lipoproteins of human serum.

The techniques of agar immunoelectrophoresis and agar double diffusion were applied to the study of the antigenicity of beta- and alpha(1)-lipoproteins separated by ultracentrifugation from normal human sera. The effects of delipidation were also investigated. It was shown that beta- and alpha(1)-lipoproteins are antigenically distinct. For each class of lipoprotein studied, a single antigenic component was demonstrated. In some, but not all, preparations of alpha(1)-lipoprotein a second, small antigenic component was detected, and identified as albumin. Absorption with lipoprotein-free serum or albumin removed this component without changing the lipoprotein band. Delipidation did not affect the antigenicity of either beta- or alpha(1)-lipoproteins. Immunoelectrophoresis, because of its high sensitivity and specificity, provides an additional criterion of purity for antigenic proteins in addition to the data that can be obtained from ultracentrifugal and free electrophoretic analysis.

Polysaccharide Hydrocolloids of Commerce

This chapter discusses the polysaccharide hydrocolloids of commerce. Following the modern trend, this name is condensed to “polysacolloids.” Polysacolloids abound in Nature as structural, storage, vascular, or functional components of plant and animal tissues, but only a limited number, all from plant sources, are of commercial importance. Most polysacolloids are complex mixtures, which are difficult to separate. Intermolecular linkages involve not only other polymers but low molecular-weight substances as well. Precipitations and solvent separations that are clean-cut for mixtures of compounds in the low molecular-weight range are usually ineffective in the presence of polymers. In addition, there is no criterion of purity for the recovered parts to be analyzed. Polysacolloids find use because of the physical properties they exhibit when they are dissolved and when they are dried. Sols of polysacolloids are viscous, and have rheological properties that help provide stability in suspensions, emulsions, and foams. These same rheological properties have subjective attributes, which provide pleasure to the sight and feel. Sols of some of the polysacolloids can be transformed into rigid structures called gels, some of which have thermal sol-gel reversibility, whereas others require chemical action .

The production, purification, and properties of Newcastle disease virus labeled with radiophosphorus

Tissue culture techniques were used to prepare high titers of Newcastle disease virus labeled with P 32. Techniques for purifying this radioactive virus are presented, and criteria for purity are described. The purified virus was fractionated by the Schmidt-Thannhauser procedure to determine the chemical distribution of P 32. The chemical components were investigated in some detail and the results indicate that while some of the small molecular phosphorus containing material in the TCA soluble fraction may not be essential to the virus, the phospholipid fraction is essential. P 32 was consistently found in the Schmidt-Thannhauser ribonucleic acid (RNA) fraction, while very little appeared in the deoxyribonucleic acid (DNA) fraction, suggesting that the virus contains little or no DNA.

Optical Activity of Homologous Series

THE optical activity of asymmetric molecules has frequently been used as a criterion of purity and also a means of identification of naturally occurring chemical compounds. In this laboratory we are particularly interested in the anteiso series of fatty acids found in natural fats1,2. These optically active fatty acids were recently synthesized in a high state of purity by Milburn and Truter3 and the optical rotations of this homologous series are therefore available to test Tschugaeff's rule4. According to this the specific rotations of members of a homologous series are inversely proportional to the molecular weights within certain limits, and the molecular rotations are constant within wide limits, that is, the molecular rotations are independent of the molecular weights.

Determination ok amylase activity in biological fluids

A rapid method for the colorimetric determination of amylase activity in serum and urine is described. This method uses amylose as substrate; it is very simple to perform, uses only 0.4 ml of serum, and can be completed in approximately 25 minutes. Preparation of amylose and a criterion of purity of the product are given. The influence of various pertinent factors has been examined and is discussed. Application of the method to 100 cases and a working ·normal” range are given.

Melting curves (temperature‐heat content curves) as criteria for purity

AbstractMethods for calculating the purity of a given sample from its melting curve developed thus far have been derived by assuming that the contaminants are immiscible with the main component in the solid phase. These methods may give rise to serious errors when applied to arbitrary samples.In the present paper a discussion is given of the behaviour of systems with solid solutions (miscibility in the solid phase), and a method is developed, resembling Wichers' “comparative method”, that is applicable to both types of systems.In addition, errors occurring in the experimental determination of melting curves are briefly discussed.Cooling curves are considered to be less suitable for the determination of purity than heating curves.A description of a simple apparatus and procedure for the determination of heating curves is given.The quantity of substance needed for a determination is about 200 mg. It is shown that the smallest amount of contaminant (s) determinable with this apparatus varies (depending on the system investigated) from 0.1 to 0.01 mol. %. The sensitivity of the method may be improved by using more sensitive thermometers.

Fractionation of Lignin by Chromatography

THE most striking characteristic of the collection of lignin ‘structures’ listed by Brauns1 is the extent of their dissimilarity. This state of affairs arises from the lack of an established criterion of purity for lignin. Purification of lignin preparations has usually been carried out according to the choice of the worker, and structural investigation undertaken without any proof of purity. Brauns's1 admirable survey on the isolation of lignin should convince any interested reader of these facts.

Immunochemical Studies on the Specific Polysaccharide of Type II Pneumococcus

Summary Preparations of type II pneumococcal capsular polysaccharides have been studied with respect to their reactivity with homologous type II antiserum and their cross reaction with rabbit anti-Friedlander B. From their capacities to precipitate antibody, from methylpentose analyses on specific precipitates formed with excess antibody, and from supernatant tests, it was concluded that certain of these preparations had undergone degradation. A sample of SII was obtained which showed no evidence of degradation by any of the immunochemical criteria employed. The findings are discussed in relation to the value of immunochemical methods in defining criteria of purity of high molecular weight substances.

The Amino Acids and Proteins

This excellent and useful book is a worth while successor to the previous book on proteins and amino acids, edited by Carl A. Schmidt. It contains a wide range of information on chemical composition, physical and chemical characteristics of the amino acids and proteins. In addition there is considerable material on the preparation and/or isolation of these substances. There is a good chapter on the criteria of purity of protein which is useful to those interested in any investigative phase of biology.

Alcohol-Insoluble Solids of Juice Vesicles and Pulp of Citrus Fruit

1. The alcohol-insoluble fraction of the juice vesicles of Valencia and navel oranges, and of the pulp of navel oranges and lemons, has been isolated from the fresh material by extraction with 80% ethyl alcohol. This fraction, which contained the cellulose, most of the hemicellulose, and pectin, was lowest in Valencia orange vesicles (mean, 9.87%) and highest in navel orange pulp (mean, 15.56%), on a dry-weight basis. 2. Since the alcohol-insoluble fraction contains the pectin, most of the carbon dioxide which can be liberated by hydrolysis with 12% HCl, and all the methoxyl groups, occur in this fraction. The ratio of methoxyl to CO2 was much lower in Valencia orange vesicles than in navel orange vesicles, navel orange pulp, or lemon pulp. 3. The carbon dioxide equivalent to the sum of the esterified and non-esterified carboxyl groups was equal to the total carbon dioxide of the alcohol-insoluble fraction obtained on hydrolysis with 12% hydrochloric acid. 4. The sum of the water-soluble and acid-soluble pectin (as calcium pectate) of the alcohol-insoluble fraction of the vesicles and pulp samples ranged between means of 26.30% in navel orange vesicles and 36.47% in lemon pulp. These values are much lower than those for the total pectin calculated from the carbon dioxide and methoxyl values. 5. To establish criteria of purity, the calcium pectate values are accompanied by corresponding values for carbon dioxide, calcium, and furfural. The percentages of calcium in the calcium pectates are generally somewhat higher than the 7.50% usually reported for pure calcium pectate, and the percentages of carbon dioxide are generally slightly higher than the 17.40% reported for the pure compound. The furfural values are in accord with those reported by other investigators. The ratios of calcium to carbon dioxide of the calcium pectates from the water-soluble pectin show satisfactory agreement with the theoretical value; except in lemon pulp, the ratios of these substances from the acid-soluble pectin tend to be lower than the theoretical value. 6. The residue that remains after extracting the pectin from the alcohol-insoluble solids of the vesicles and pulp is composed of cellulose and hemicellulose and a comparatively small amount of firmly bound pectin that is difficult to extract and determine quantitatively. 7. The sum of the carbon dioxide in the aqueous extract, acid extract, and residue amounted to 95.4% and 100.9% (mean values) of the total carbon dioxide of the alcohol-insoluble solids in the vesicles and pulp, respectively. In the aqueous and acid extracts, calcium pectate accounted for more than 85% of the carbon dioxide dissolved by the extractants. 8. As a measure of the degree of esterification of the alcohol-insoluble fractions, the ratio of methoxyl to galacturonic acid was lowest in the Valencia orange vesicles (mean, 0.107) and highest (mean, 0.134) in navel orange pulp. In a polygalacturonic acid, the number of carboxyl groups that are free, esterified, or combined with cations is not a constant amount but varies considerably with the method of preparation.

Electrophoresis as a Criterion of Purity in Proteins

Electrophoresis as a Criterion of Purity in Proteins

Erratum: Electrophoresis as a Criterion of Purity in Proteins

We have been informed that reference 14 in the article by Eugene L. Hess ( Science , 113, 709 [1951]) is to the new journal Arkiv för Kemi and not to Arkiv Kemi, Mineral., Geol.

Erratum: Electrophoresis as a Criterion of Purity in Proteins

Erratum: Electrophoresis as a Criterion of Purity in Proteins

Electrophoresis as a criterion of purity in proteins.

WE HAVE been informed that reference 14 in the article by Eugene L. Hess ( Science , 113, 709 [1951]) is to the new journal Arkiv for Kemi and not to Arkiv Kemi, Mineral., Geol. —EDITORS.