A new sensitive and specific test for cobalt

Summary The p-nitrophenylhydrazone of 3-isonitrosopentane-2-one gives in ammoniacal solution a red coloration with cobalt, which provides a sensitive and specific test. Cyanide as well as a high concentration of ammonium salts prevent the test. Palladium, silver, nickel, copper and most common cations and anions do not interfere.

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Zusammenfassung Dasp-Nitrophenylhydrazon von 3-Isonitrosopentan-2-on gibt in ammoniakalischer Lösung mit Kobalt eine Rotfärbung, die dessen empfindlichen und spezifischen Nachweis ermöglicht. Cyanid sowohl wie eine hohe Ammoniumsalzkonzentration verhindern die Probe. Palladium, Silber, Nickel, Kupfer und die meisten der gewöhnlichen Kationen und Anionen verursachen keine Störung.

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Résumé Lap-nitrophenylhydrazone de l'isonitroso-3 pentanone-2 donne en solution ammoniacale une coloration rouge avec le cobalt que l'on utilise comme essai sensible et spécifique. Les cyanures, ainsi que de fortes concentrations en sels de l'ammonium, gênent l'essai. Le palladium, l'argent, le nickel, le cuivre et les cations et anions les plus fréquents n'interfèrent pas.

     

A simple specific test for inner-ring o-quinones

A simple specific test for inner-ring o-quinones is introduced. The test consists of the reaction of the quinone with 3,4-dimethoxyamline in hot acetic acid to give dye(s) absorbing near 600 mμ Spot test and colorimetric rnoditications of the test are described Other types of quinones and ketonic compounds give negative results The spectra of the o-quinones in sulfuric acid are also presentedWith the new method, fairly specific tests are now available for (a) inner-ring p-quinones, (b) inner-ring o-quinones, and (c) terminal ring o- and p-quinones     

A new procedure for preparing microcrystalline cellulose

Russian Journal of Applied Chemistry - A procedure was developed for preparing microcrystalline cellulose, involving hydrolytic treatment of technical-grade (unbleached kraft) wood pulp, followed...     

A new sensitive and specific test for vanadium with sulphosalicylic acid

A very sensitive and specific test for vanadium^V is described using sulphosalicylic acid as reagent. When this reagent is brought into contact with solid vanadium^V (a drop of the test solution evaporated to dryness on a watch glass) in the presence of concentrated sulphuric acid or 80% syrupy phosphoric acid, a blue colour is developed. Using this colour reaction, it is possible to detect 0.05 μg of vanadium^V in 0.05 ml of test solution. Aluminium^III, arsenic^V, beryllium^II, cadmium^II, chromium^III, chromium^VI, copper^II, iron^III, molybdenum^VI, nickel^VI, tungsten^VI, uranium^VI and vanadium^IV do not interfere with this colour test, although some of them are known to form coloured complexes with sulphosalicylic acid under different conditions. Reducing agents like iron^II, uranium^IV, molybdenum^V and hydroquinone discharge the colour. The colour of the vanadium^V-sulphosalicylic acid compound is also discharged if the temperature is raised to 60°, though it reappears on cooling.     

Modification of microcrystalline cellulose with pyridone derivatives for removal of cationic dyes from aqueous solutions

Microcrystalline cellulose (MCC) was modified with pyridone derivatives such as pyridone diester (PDE) and pyridone diacid (PDA) by using succinic acid anhydride as a linker. The modified MCCs were characterized by the fourier transform infrared spectroscopy, scanning electron microscopy, thermal gravimetric analysis, elemental analysis and solid state ¹³C NMR. The adsorption capacities of the modified MCCs to cationic dyes were examined by using methylene blue (MB) as a model dye. It was found that the kinetic adsorption data followed the pseudo-second-order kinetic model, and the adsorption equilibriums were reached less than 10 min. The isothermal adsorption data were fitted with the Langmuir isotherm model very well, from which the maximum adsorption capacities of the MCCs modified with PDE and PDA were determined to be 101.01 and 142.86 mg/g, respectively. Further investigation showed that the modified MCCs were pH-dependent for adsorption of MB in aqueous solutions. The modified MCCs could be used for removal of MB from an aqueous solution at pH 8, and reused by regeneration in an acidic solution. It was tested that the modified MCCs had a high reusability for removal of MB from aqueous solutions, and still maintained high adsorption capacities even after multiple cycles of desorption–adsorption processes. Hence, the MCCs modified with PDE and PDA could be an effective and efficient approach to removal of cationic dyes from aqueous solutions.     

A physico-chemical characterisation of new raw materials for microcrystalline cellulose manufacturing

A detailed physico-chemical characterisation of potential new cellulose sources (rice husk, hemp stalk, and coniferous needles), and microcrystalline cellulose (MCC) manufactured from them, was made in this work. The length and the width of the cellulose crystallites were determined by wide-angle X-ray scattering (WAXS), crystallinities were studied by means of WAXS and solid state cross polarisation magic angle spinning ¹³C nuclear magnetic resonance (NMR) spectroscopy, and the packing and the cross-sectional shape of the microfibrils were determined by small-angle X-ray scattering. When MCC was prepared from rice husks and hemp stalks an acceptable yield was obtained. Crystallinities obtained with solid state NMR spectroscopy and WAXS were highest for MCC prepared from hemp stalks, and lowest for rice husk MCC. The crystallite sizes of MCC samples studied in this work varied more than in those MCC samples which were prepared from conventional plant sources, and crystallite size and cellulose crystallinity were related. When taking into account rather high values of specific surface, hemp stalks and rice husks appear as a promising raw materials for MCC production.     

On the reactivity of innercomplex-bonded palladium : A new specific test for cyanides in alkaline solutions

It has been found that the innercomplex salts of palladium with dimethylglyoxime, (benzildioxime and furildioxime), salicylaldoxime and 8-hydroxyquinolinc do not enter into redox reaction with carbon monoxide, cither in solid or in molecular dispersed form.Solutions of palladium-dimethylglyoxime and palladium-salicylaldoxime in alkali hydroxide or ammonia are masked with respect to many reactions of the palladium as well as of the organic components. In alkaline solutions, when adding alkali cyanide, demasking occurs, with the deliberation of the innercomplex forming organic components. For the processes of dissolution and demasking appropriated equations are suggested.The demasking of dimethylglyoximc in alkaline solutions of palladium dimethylglyoxime permits a new sensitive test for cyanide ion. This cyanide test seems to be appropriate for the detection of illuminating gas.Palladium hydroxyquinorate is insoluble in solutions of alkali cyanides, though it is not precipitable from cyanide containing palladium solutions. An explanation for this “false equilibrium” is suggested.     

A selective and specific solid-state capillary spot test for bismuth(III) with ammonium thiocyanate

A capillary solid-state spot test has been developed for specific detection of bismuth using ammonium thiocyanate as reagent. The reactants were kept separate in a glass capillary by introducing a glass wool plug between the reactants and then they were allowed to react. A semiquantitative determination of bismuth has also been achieved.     

Selectivity tuning of cyclodextrin derivatives by specific substitution

A new, highly enantioselective cyclodextrin derivative combining the properties of heptakis(6‐O‐tert‐butyldimethylsilyl‐2,3‐di‐O‐methyl)‐β‐cyclodextrin and heptakis(2,3‐di‐O‐acetyl‐6‐O‐tert‐butyldimethylsilyl)‐β‐cyclodextrin was prepared by exchanging a methyl group for an acetyl substituent in a single glucose unit of heptakis(6‐O‐tert‐butyldimethylsilyl‐2,3‐di‐O‐methyl)‐β‐cyclodextrin. A comparative evaluation of the separation capabilities showed that the enantioselectivity of both “parent” cyclodextrin derivatives is transferred to the new chiral stationary phase.     

A test for cobalt

Summary Cobalt may be detected by means of dimethylglyoxime and iodide in slightly acid solution. Yellow colorations are obtained in test tube and in spot tests. Yellow to red crystals are obtained on the microscope slide. The data on sensitivity are compiled in Table 1.

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Zusammenfassung Kobalt kann in schwach saurer Lösung mit Dimethylglyoxim und Jodid nachgewiesen werden. Gelbfärbungen werden dabei in Reagensglasversuchen und in Tüpfelproben erhalten. Unter dem Mikroskop können charakteristische gelbe bis rote Kristalle erkannt werden. Alle Angaben über die Empfindlichkeit der Probe sind in Tabelle 1 zusammengefaßt.

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Résumé Le cobalt peut être recherché en solution faiblement acide avec la diméthylglyoxime et un iodure. On a obtenu des colorations jaunes dans des tubes à essais et des expériences à la touche. Sous le microscope, on peut former des cristaux caractéristiques, rouges et jaunes. Toutes les données sur la sensibilité de l'essai sont consignées dans le tableau 1.

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With 4 figures.     

丙酮酸及其衍生物的某些特异反应研究

合成了3个丙酮酸的衍生物.结果发现,2'-(N-苄氧羰基甘氨酰脯氨酰胺基)丙酮酸乙酯不稳定,该化合物可以通过自催化水解；与其他脂肪酸不同,丙酮酸与N,N-二异丙基碳二亚胺(DIC)反应形成稳定的加合物,该加合物对醇以及二级胺不敏感；在酰肼的作用下,1-氯-N,N,2-三甲基丙烯胺不能将丙酮酸转化为丙酮酰氯,而是得到2-羟基丙烯酸异丁基酯.     

Assignments of carbon NMR resonances for microcrystalline ubiquitin

Solid-state NMR 2D spectroscopy was used to correlate carbon backbone and side-chain chemical shifts for uniformly (13)C,(15)N-enriched microcrystalline ubiquitin. High applied field strengths, 800 MHz for protons, moderate proton decoupling fields, 80-100 kHz, and high magic angle sample spinning frequencies, 20 kHz, were used to narrow the most of the carbon line widths to 0.5-0.8 ppm. Homonuclear magnetization transfer was effected by matching the proton RF field to the spinning frequency, the so-called dipolar-assisted rotational resonance (DARR) (Takegoshi, K.; Nakamura, S.; Terao, T. Chem. Phys. Lett. 2001, 344, 631-637), and a mixing time of 20 ms was used to maximize the intensity of one-bond transfers between carbon atoms. This polarization transfer sequence resulted in roughly 14% transfer efficiencies for directly bonded carbon pairs and 4% transfer efficiencies for carbons separated by a third carbon. With this simple procedure, the majority of the one-bond correlations was observed with moderate transfer efficiencies, and many two-bond correlations were also observed with weaker intensities. Spin systems could be identified for more than half of the amino acid side chains, and site-specific assignments were readily possible via comparison with 400 MHz (15)N-(13)C-(13)C correlation spectroscopy (described separately).     

Assignment of the backbone resonances for microcrystalline ubiquitin

Site-specific assignments for the solid-state NMR spectra of uniformly 13C,15N-enriched ubiquitin are described. The assignments are derived from three three-dimensional 15N-13C-13C correlation spectra collected at 400 MHz on microcrystalline material. A few residues (the loop near Threonine 9 and the C-terminal fragment) were missing and correspond to regions previously reported to be mobile on the basis of X-ray crystallography and solution NMR studies. A few additional sites exhibit shifts that differ from previously reported solution NMR assignments. Nonetheless, these de novo assignments indicate close agreement between the chemical shifts observed in solution and those in microcrystalline or precipitated solids. The methods utilized are likely to be generally applicable for other noncrystalline, nonsoluble proteins.     

Some distinguishing tests for α-amino acids and a specific spot test for lysine

Tests are described for differentiation between neutral, basic, and acidic amino acids based on the formation of nickel dimethylglyoxime precipitate from an equilibrium mixture containing Ni²⁺, dimethylglyoxime and Ni²⁺, dimethylglyoxime-glycine. A highly sensitive and specific test for lysine is described, based on the formation of nickel dimethylglyoxime precipitate in a drop of the equilibrium mixture, by the reaction of the volatile amino aldehyde, produced by the oxidative deamination-decarboxylation of lysine. Other basic amino acids, i.e., arginine and histidine do not interfere, and the test can be applied for lysine in a mixture with other amino acids.     

A specific enzyme electrode for urea

A truly specific, simple enzyme electrode is described for the assay of urea in blood serum. The sensor used is the newly developed air-gap electrode of R??i?ka and Hansen, and has advantages of speed of response and specificity over earlier enzyme electrodes for urea. Potassium, sodium and ammonium ions and other organic and inorganic species present in blood do not interfere. Linear curves are obtained from 2 · 10^-2M to 1 · 10^-4M urea with slopes close to Nernstian (about 0.90 pH/decade). Urea in blood was assayed with an accuracy of 2.2% and a precision of 2.0% with immobilized urease; only 3–5 min is required per assay. The electrode was used for a month and almost 500 assays with excellent results. Since the sensor never touches the sample solution, problems caused by blood components which block membrane pores are avoided.     

A specific enzyme electrode for L-phenylalanine

A specific enzyme electrode procedure is described for the rapid assay of L-phenyl- alanine. The enzyme L-phenylalanine ammonia lyase is used, which cleaves L-phenyl-alanine to ammonia. The ammonia liberated is measured with an air-gap electrode. The procedure is specific; L-tyrosine and other amino acids do not interfere, nor do Na⁺ or K⁺ ions. As little as 5 · 10^-5 M L-phenylalanine can be determined.