Precipitation of barium chromate in the presence of strontium and lead by complexation followed by volatilization of ammonia

Cation-release is used to precipitate barium chromate from homogeneous solution in the presence of lead and strontium. MEDTA or DCTA is added to complex the metal ions at pH 10.3 (adjusted with ammonia). On heating, the ammonia slowly volatilizes and the consequent increases in acidity releases the metal ion bound in the least stable chelate (barium). Precipitation is about 99.3-99.7% complete at pH 6.7-6.8, with less than 0.1% co-precipitation of lead or strontium. Lower pH values can be attained by volatilizing acetic or hydrochloric acid into the solution in a closed system.     

Electro chromatography on paper

The term 'electrochromatography' is used to denote the specific cases where chromatography and ionophoresis operate simultaneously. The electric field may be applied either in the direction of flow of the solvent or at right angles to it. The filter paper is previously treated with the relevant buffer solution and the developing solvent too is saturated with it. Colloidal graphite painted on the two sides of the paper serves as electrodes.A detailed study has been made of a number of amino acids at different pH's with phenol-buffer as the developing solvent. On ordinary paper acidic amino acids move towards the anode, basic ones towards the cathode, neutral amino acids do not move at all. Using buffer-treated papers, however, the movement depends upon the pH of the buffer and the isoelectric points of the amino acids. By choice of suitable pH and application of electric field in proper direction amino acids having very close RF values (except isomers) can be separated from one another.     

Studies on paper chromatography

Zusammenfassung In Gegenwart von Komplexon tritt durch Bildung eines gefärbten Komplexes zwischen Zirkonium und dem Reagens Brenzcatechinviolett eine tiefblaue Färbung auf. Nahezu alle störenden Ionen werden durch Komplexon maskiert. Nur Sb^III und Sn^IV sind abzutrennen, was in Gegenwart von Komplexon mit Ammoniak leicht vor sich geht. Die Empfindlichkeit wird durch die meisten Kationen bis zu Grenzkonzentrationen l1000 nicht beeinflußt und beträgt 0,6 [A] 0,03, pD=4,7. Komplexbildende Anionen stören. Die Störung durch Fluorid-Ion kann jedoch mittels Berylliumzugabe ausgeschaltet werden.Den Firmen Riedel-de Haën, Seelze/Hann., und B. Siegfried, Zofingen, Schweiz, danken wir herzlichst für die Überlassung von Chemikalien.     

Studies on paper chromatography

Conclusion A study with filter paper strips partially impregnated with the precipitating agent with or without colloid as the fixing agent reveals that in the case of spotted strips run in aqueous alcoholic mixture as the solvent, uniform bands of the precipitate are formed. In these cases, chromatographic observations such as measurement of S and R_f values is possible. Rhythmic structures can also be obtained with these strips when the reactant solution is used as the solvent. In the absence of colloids rhythmic structures are obtained at a high concentration and the bands obtained have to be washed and repeatedly dipped in hot water in order to clear the structure of rings present underneath. In the presence of colloid, rhythmic vertical bands are obtained at a much lower concentration and the clear interspaces are visible even without washing. Thus an independent method for obtaining rhythmic structures on filter paper with a technique very similar to chromatography has been developed.Part I see Z. analyt. Chem. 149, 339 (1956).     

Precipitation chromatography theory

A discussion is given of the behavior of a mathematical model chosen to approximate conditions during precipitation chromatographic fractionation of polymer (Baker Williams fractionation). With only one molecular weight species of polymer a complete solution of the mathematical model was obtained. With more than one species it was necessary to use a computer solution. Curves showing the movement of polymer containing one and two species of polymer are given for a variety of conditions of operation. It was found that the degree of fractionation of polymer approaches a limiting value with increasing length of column. Under some conditions the degree of fractionation may go through a maximum with length of column. The equilibrating distance (distance of travel of the liquid phase required to establish equilibrium of polymer between the liquid and the bed) was found to be very important in determining the fractionation.     

Precipitation of barium chromate from homogeneous solution using complexation and replacement A separation of barium from relatively large amounts of strontium and lead

A new procedure is presented that efficiently separates barium from relatively large amounts of strontium and lead. The barium is precipitated as the chromate from a solution in which the multivalent cations are complexed with EDTA. The barium ions are homogeneously released in solution when magnesium ions are slowly introduced into the solution. The magnesium ions gradually replace the barium ions from their EDTA complexes, bringing about a precipitation of barium chromate from homogeneous solution.

This slow formation of barium chromate crystals holds co-precipitation to a minimum and produces crystals that are easily filtered and washed. More than 99.7% of the barium can be precipitated as the chromate, with less than 0.6% of the strontium, when the two ions are in equal molar concentration.     

The predawn of paper chromatography

Summary The activities of F.F. Runge, F. Goppelsroeder and R.E. Liesegang are outlined. The technique of capillary analysis is described and its shortcomings elaborated. Tswett's use of filter paper to imitate plant tissues is explained and finally, the considerations of Izmailov and Shraiber eventually leading to thin-layer chromatography are summarized.     

Anion-exchange paper chromatography of metal ions

The migration of 26 ions on anion-exchange paper is studied with five different complexing solvents. The results are reported as a function of the sign of the charge on each ion determined electrochromatographically. Several possible separations are presented, but it is shown that the prediction of separations, knowing only the charge on several substances, is impossible. It is also demonstrated that ion-exchange column experiments and ion-exchange paper experiments do not necessarily yield identical results.     

Inverse gas chromatography study on partially esterified paper fiber

Paper fiber was treated in a heterogeneous esterification reaction with four different fatty acids. This fiber was used to strengthen polyethylene (PE) composites. Modified and unmodified cellulose fiber was characterized with inverse gas chromatography. In previous work, characterization was also carried with X-ray photoelectron spectroscopy (XPS), solid-state NMR, differential scanning calorimetry and thermogravimetry. Individual fibers were found to be covered with the corresponding esters (cellulose undecylenate, undecanoate, oleate, stearate) with partial degrees of substitution of the cellulose. Comparison of XPS and NMR results showed that the surface degree of substitution of the cellulose fiber was higher than for the bulk, showing that the esterification reaction was a surface phenomenon. The aim of this work was to acquire information on the surface characteristics of the fiber and to see whether it could be correlated to PE composite mechanical strength results. The conclusions are that polar probes seem to diffuse more into the fibers than the non-polar probes, as the non-polar component of the surface tension of the modified fiber is much lowered towards that of PE, while donor-acceptor characteristics are hardly changed by esterification. The ester with the lowest non-polar component of the surface energy, the oleate, also gives the composite with the best mechanical properties.     

Identification of aromatic amines by paper chromatography

Summary Aromatic amines have been separated by paper chromatography using butanol-acetic acid-water (401050) for development and 1.0% K₂S₂O₈ solution (with traces of Ag) for identification.

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Zusammenfassung Aromatische Amine wurden papierchromatographisch mit Butanol-Essigsäure-Wasser (401050) getrennt und mit 1%iger K₂S₂O-Lösung (mit Spuren Ag) nachgewiesen.

     

Analysis of inorganic compounds by paper chromatography

A Chromatographic method for the separation and detection of lead, silver, and mercury by extraction with organic solvent mixture on strips or sheets of filter paper, is described. Study of various physico-chemical factors responsible for the separation of cations has been made.

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Zusammenfassung Es wird eine chromatische Methode zur Trennung und Feststellung von Blei, Silber und Quecksilber durch Extraktion mittels Gemischen aus organischen Flüssigkeiten auf Papierstreifen beschrieben und die verschiedenen für die Trennwirkung verantwortlichen physikalisch-chemischen Faktoren werden betrachtet.

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The thanks 01 the author are due to Dr. N. Ghatak, D. So., Chemical-Examiner to the Government of Uttar Pradesh, for his keen interest in this investigation.     

Paper chromatography of inorganic ions : The paper chromatography of germanium

Germaniuni(IV) may be separated from As and many other elements by paper chromatography with butanol saturated with 1 N HCl. The R_F value of germanium (IV) is 0.25 – 0.29.     

Identification of stilbene derivatives by paper and gas chromatography and paper eleetrophoresis

Summary Some stilbene derivatives have been identified by using paper chromatography in five different solvents systems, paper electrophoresis in two different electrolytes, and gas chromatography to detect cleavage products.

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Zusammenfassung Einige Stilbenderivate wurden chromatographisch mit fünf verschiedenen Lösungsmittelsystemen identifiziert, elektrophoretisch in zwei verschiedenen Elektrolyten und gaschromatographisch unter Nachweis der Spaltprodukte.

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Résumé On a identifié quelques dérivés du stilbène par Chromatographie sur papier dans 5 systèmes différents de solvants, par électrophorèse (sur papier) dans deux électrolytes différents et par Chromatographie en phase gazeuse pour déceler les produits de coupure.

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Dedicated to the 60th birthday of Prof. Dr.M. Jureek, Dr. Sc.