Substoichiometric determination of manganese by neutron-activation analysis

A simple and rapid method for the substoichiometric determination of traces of manganese in various materials by neutron-activation analysis has been developed. After dissolution of the irradiated test sample, manganese(II) carrier is added and subsequently oxidised by peroxodisulphate to the heptavalent state. The permanganate thus formed is finally extracted into chloroform as tetraphenylarsonium permanganate using a substoichiometric amount of tetraphenylarsonium chloride. This single separation step isolates radiochemically pure manganese-56 in the analysis of a relatively simple material in which interfering elements (gold, rhenium, etc.) are absent. When this is not true, a preliminary separation of manganese from the irradiated sample, based on the extraction of manganese diethyldithio-carbamate into chloroform and followed by stripping of the manganese with dilute sulphuric acid, must be used. A simultaneously irradiated standard containing manganese must be treated in exactly the same way as a test sample. In the materials analysed by the new method 10(-5) to 10(-3)% of manganese has been determined.     

Quantitative elektrolytische erzeugung von permanganationen

In order to realize coulometric permanganatometric determinations theoretical and experimental investigations have been carried out. By the study of anodic potentials on platinum and of electrolytic oxydation processes the possibility of the quantitative formation of permanganate ions from manganous sulfate in aqueous sulfuric acid solutions could be demonstrated. Under definite conditions of anodic potential, concentration of anolyte, and relation between manganous sulfate and sulfuric acid, by different current densities, a quantitative generation of permanganate ions can be attained, in a sure and simple manner, and can also be utilized for different secondary oxidation processes.Thus the fundamental condition has been created for the realization and the development of the coulometric permanganatometry, and thereby the possibility of the coulometric generation of permanganate and standardization of volumetric solutions based on permanganate has also been created, as well as for the further utilization of the coulomb as a standard in analytical chemistry.     

Permanganate-based chemiluminescence analysis of ferulic acid using flow injection.

A simple, sensitive and rapid flow-injection chemiluminescence method has been developed for the determination of ferulic acid based on the chemiluminescence reaction of ferulic acid with potassium permanganate in a nitric acid medium. A strong chemiluminescence signal was observed when ferulic acid was injected into an acidic potassium permanganate solution in a flow-cell. The present method allowed the determination of ferulic acid in the concentration range of 6.0 x 10(-6) to 2.0 x 10(-4) mol l(-1); the detection limit (3sigma) for ferulic acid was 9.6 x 10(-8) mol l(-1). The relative standard deviation was 1.0% for 11 replicate analyses of 2.0 x 10(-4) mol l(-1) ferulic acid. The proposed method was applied to the determination of ferulic acid in real samples with satisfactory results. Moreover, the reaction mechanism of the chemiluminescence system was primarily considered.     

The determination of organic substances by the oxidation with permanganate: XVIII. The oxidation of malonic acid

The oxidation of malonic acid with permanganate was studied under various acidity conditions. Analytical procedures, based on oxidation with excess reagent in a sodium carbonate medium and titration of the oxalate or manganese dioxide formed or of unconsumed permanganate, are proposed. On the basis of successive oxidation in sodium carbonate and sulfuric acid media, a titration determination, involving complete oxidation of malonic acid to carbon dioxide and water, was developed.     

Spectrophotometric determination of copper in alkaline solutions and evaluation of some hydroxy-substituted 1,10-phenanthrolines as chromogenic reagents

Seven new hydroxy-substituted 1,10-phenanthroline derivatives have been evaluated as chromogenic reagents for the determination of copper in strongly alkaline solution. The most sensitive of these, 2,9-dimethyl-4,7-dihydroxy-1,10-phenanthroline, has proven to be highly effective in a simple, rapid procedure for determining trace amounts of copper in sodium hydroxide, potassium carbonate, sodium phosphate or ammonium hydroxide.     

Chemiluminescence determination of indole derivatives in human body fluids and soil by flow injection analysis using potassium permanganate

A simple, sensitive and rapid flow-injection chemiluminescence (CL) method has been developed for the determination of indole derivatives including indole-2,3-dione (isatin) and indole-3-acetic acid (IAA), based on the increased CL reaction of potassium permanganate-formaldehyde system in acidic medium. Strong CL was observed when the indole derivatives were injected into the acidic potassium permanganate solution in a flow-cell. Under the optimum conditions, the linear range of the determination was 0.1–100.0 µM for isatin and 0.01–10.0 µM for IAA. The detection limit (3σ) was 10.0 nM for isatin and 1.0 nM for IAA. The method has been successfully applied to the determination of isatin in biological samples and of IAA in biological samples and soil extracts with satisfactory results.     

A Facile One‐Pot Route for the General Synthesis of Triazole Linked Chiral 2‐Substituted Benzimidazoles

One‐pot protocol for the synthesis of novel class of triazole linked 2‐sugar and 2‐aryl substituted benzimidazoles has been developed. The rapid and simple method involves copper (I) catalyzed simultaneous formation of benzimidazole and triazole rings at room temperature and in high yield.     

Novel headspace gas chromatographic method for determination of oxalate in oxygen delignification liquor

A novel headspace gas chromatographic (HS-GC) method is demonstrated for an indirect determination of oxalate in oxygen delignification liquors. A small volume (50-100 microL) of liquor sample is introduced into a sampling vial that contains 1.0 mL of 2 mol/L sulfuric acid. After removal of carbon dioxide (generated from carbonate in the acidic medium) by heating, the sample was mixed with a 0.5 mL of 0.02 mol/L potassium permanganate solution in a closed testing vial. At an elevated temperature (70 degrees C), the oxalate in the sample is rapidly converted to carbon dioxide by reacting with permanganate. The carbon dioxide in the headspace can be measured by gas chromatography with a thermal conductive detector. Using a multiple headspace extraction (MHE) measurement technique, the kinetics of formation of the carbon dioxide from the other organic species in the sample can be determined, and thus a correction can be made for minimizing the interferences. The present method is simple, accurate and can be easily automated.     

Rapid Flow-Injection Method for the Determination of Colistin by Sensitized Chemiluminescence Using the Acidic Permanganate–Sulfite System

Abstract

A simple, rapid, and sensitive chemiluminescence method for the determination of colistin (Polymyxin E), a cyclic polypeptide with antibiotic effect produced by certain strains of Bacillus polymyxa, has been developed by combining a flow-injection technique and the bacteria's sensitizing effect on the chemiluminescence reaction between sulfite and acidic permanganate. The optimum conditions for chemiluminescence emission were established. The chemiluminescence was proportional to the log of concentration of colistin over the range 4–100 µg mL^?1 (3.5–87 µM). The detection limit was 1.2 µg mL^?1 (1.0 µM) of colistin. The method has been satisfactorily used for the determination of colistin in pharmaceuticals.     

Solventless protocol for efficient bis-N-boc protection of adenosine, cytidine, and guanosine derivatives

A solvent-free reaction employing a simple low-energy ball mill apparatus converts the amino groups of adenosine, 2-deoxyadenosine, cytidine, 2-deoxycytidine, guanosine, and 2-deoxyguanosine as well as some of their ribosyl O-protected derivatives to the corresponding bis-N-Boc carbamates. In the case of guanosine compounds, the carbonyl group of the base moiety was also blocked as its O-Boc enol carbonate. A variation of this approach using transient in situ O-silylation permitted the preparation of bis-N-Boc nucleosides in which the sugar hydroxyls were unprotected. The ball mill reactions were rapid, convenient, and very high-yielding except in the case of the guanosine compounds. This highly efficient method protects the amino groups of these nucleosides with a base stable and acid labile group suitable for further synthetic manipulation.     

Volumetric estimation of potassium permanganate and potassium dichromate in mixtures with oxalic acid

1. A simple method has now been developed for the volumetric estimation of potassium permanganate and potassium dichromate in mixtures The method consists in taking an aliquot volume of the mixture in an Erlenmeyer flask, adding sufficient quantities of sulphuric acid and manganous sulphate (catalyst) and titrating with a standard solution of sodium oxalate or oxalic acid run in from the burette, until the colour changes from orange-red to yellow. The oxalic acid run ingives a measure of the permanganate present in the mixture Then the mixture in the flask is titrated with a standard solution of Mohr's salt using diphenylbenzidine as indicator. The volume of Fe⁺² solution run in the second stage gives a measure of the dichromate present in the original mixture. 2. The reverse titration does not give accurate results, because it is affected by the induced reaction between oxalic acid and dichromate which is induced by the reaction between oxalic acid and permanganate during the first stage of the reaction. This induced reaction has been studied in some detail.     

Construction and Evaluation of a LEGO Spectrophotometer for Student Use

A simple visible-wavelength spectrophotometer has been constructed for educational purposes. The spectrophotometer contains simple, inexpensive components students can easily work with (small flashlight bulbs, batteries, etc.) and uses LEGO pieces for construction of the optical support elements. The spectrophotometer was designed to give students hands-on experience with typical spectrophotometer modules so that they may understand the important stages in the design of a scientific instrument. The spectrophotometer was characterized by examining an absorption spectrum and calibration curves of potassium permanganate.     

Studies on Mercury Pollution: Microdetermination of Mercury in Biological Materials by Cold Vapour Atomic Absorption Spectrometry

Abstract

A simple, rapid, precise and accurate method for the determination of mercury in biological material is described. Biological samples were digested with nitric acid and acidified potassium permanganate and determined by cold vapour analyser. The proposed method was successfully employed for the determination of mercury in samples of fish, hair and blood.     

Acrylamide: update on selected research activities conducted by the European food and drink industry

This paper reviews the progress made by the European food and drink industry (CIAA) on acrylamide with regard to analytical methods, mechanisms of formation, and mitigation research in the major food categories. It is an update on the first CIAA review paper, "A Review of Acrylamide: An Industry Perspective on Research, Analysis, Formation and Control." Initial difficulties with the establishment of reliable analytical methods, in most cases, have now been overcome, but challenges remain in terms of the need to develop simple and rapid test methods and certified reference materials. Many trials have been conducted under laboratory and experimental conditions in a variety of foods, and a number of possible measures have been identified to relatively lower the amounts of acrylamide in food. Promising applications were studied in reconstituted potato models by addition of amino acids or use of asparaginase. In bakery wares, predictive models have been established to determine the role of ammonium carbonate and invert sugar in acrylamide formation. Studies in several commercial foods showed that acrylamide is not stable over time in roasted and ground coffee. Some progress in relatively lowering acrylamide in certain food categories has been achieved, but at this stage can only be considered marginal. Any options that are chosen to reduce acrylamide in commercial products must be technologically feasible and must not adversely affect the quality and safety of the final product.     

Mechanistic and spectroscopic investigations of oxidative degradation of aspirin by aqueous alkaline permanganate

The kinetics of oxidation of aspirin (ASP) by permanganate in alkaline medium at a constant ionic strength of 0.06 mol dm⁻³ was studied spectrophotometrically using a rapid kinetic accessory. The reaction between permanganate and aspirin in alkaline medium exhibited 1:4 stoichiometry (aspirin: permanganate). The reaction was of first order in [permanganate ion] and had less than unit order in both [ASP] and [alkali]. A decrease in the dielectric constant of the medium decreased the rate of reaction. The effect of added products and ionic strength of the reaction medium have been investigated. The oxidation reaction in alkaline medium has been shown to proceed via a permanganate–aspirin complex, which decomposes slowly in a rate determining step followed by other fast steps to give the products. The main products were identified by spot test and spectroscopic studies. A suitable mechanism is proposed. The reaction constants involved in the different steps of the mechanism were derived. The activation parameters with respect to the slow step of the mechanism were computed and discussed and thermodynamic quantities were also determined.     

Validation by Molecular Dynamics of the Major Components of Sugarcane Vinasse,On a Surface of Calcium Carbonate (Calcite)

There is ongoing interest in the alcohol industry to significantly reduce and/or add value to the liquid residue, vinasse, produced after the distillation and rectification of ethanol from sugar cane. Vinasse contains potassium, glycerol, and a protein component that can cause environmental issues if improperly disposed of. Currently, some industries have optimized their processes to reduce waste, and a significant proportion of vinasse is being considered for use as an additive in other industrial processes. In the manufacture of cement and asphalt, vinasse has been used in the mixtures at low concentrations, albeit with some physical and mechanical problems. This work is the first molecular approximation of the components of the sugar cane vinasse in an industrial context, and it provides atomic details of complex molecular events. In the current study, the major components of sugar cane vinasse, alone or complexed on the surface of calcium carbonate, were modeled and simulated using molecular dynamics. The results showed that the protein component, represented by the mannoprotein Mp1p, has a high affinity for forming hydrogen bonds with potassium and glycerol in the vinasse. Additionally, it provides atomic stability to the calcium carbonate surface, preserving the calcite crystalline structure in the same way potassium ions interact with the carbonate group through ion–dipole interactions to improve the cohesion of the modeled surface. On the contrary, when the glycerol molecule interacts with calcium carbonate using more than two hydrogen bonds, it triggers the breakdown of the crystalline structure of calcite expanding the ionic pair.     

Sorption of cobalt on modified clinoptilolites

A method of radioactivation analysis has been developed for the substoichiometric determination of cobalt, copper and manganese in glass and glass-making materials. The substoichiometric extraction of cobalt with α-nitroso-β-naphthol was studied and simple procedures are suggested for the determination of the three elements. Cobalt is extracted substoichiometrically as α-nitroso-β-naphtholate into chloroform from solution of pH 6.2, copper as dithizonate in carbon tetrachloride from weak acidic solution, and manganese as tetraphenylarsonium permanganate into chloroform after oxidation to permanganate. Contents from 2 ppm to 3 ppb of cobalt, copper and managanese were analysed in glass-making materials, and it is shown that the method for their determination is reliable and superior in accuracy and reproducibility.     

Titrimétrie des ions céreux par le permanganate

A direct titration method of cerous ions by means of permanganate in a nearly neutral pyrophosphate solution is described.The reaction has been studied both potentiometrically and amperometrically. The latter method yields the bcbt results and permits the use of a particularly simple and practical device.The only interfering clement is in fact manganese.     

Chemiluminescence determination of melatonin and some of its derivatives using potassium permanganate and formaldehyde system

It was found that melatonin and its derivatives, such as N-acetyl- 5-methoxytryptamine (MT), N-acetyl-5-hydroxytryptamine (NAS), 5-Methoxytrypt- amine (5-MT), 5-Methoxyindolyl acetic acid (5-MIAA) and N-acetyl-5-methoxy- 6-hydroxytryptamine (6-HMT) would give chemiluminescence in the acidic potassium permanganate solution, and formaldehyde would enhance this chemiluminescent reaction greatly. The optimum conditions for this chemiluminescent reaction were studied in detail by a flow injection system. A new simple rapid method has been developed under the optimum conditions for determination of melatonin. This method has the advantages of high sensitivity, wide range of linear response and low detection limit. On the basis of investigation of chemiluminescent, fluorescent and UV spectra of melatonin in acidic solution containing potassium permanganate and formaldehyde, a possible mechanism of this reaction was proposed.     

氢化物发生电加热石英管原子吸收法测定包头铁矿中的砷、锑、铋

研究了氢化物发生原子吸收法测定包头矿中痕量砷、锑、铋的分析方法,试验确立了反应条件,建立了以KI、抗坏血酸、硫脲为还原体系,消除试样中共存元素的干扰,利用KMnO4消除锑对砷的干扰.砷、锑、铋的检出限可分别达到:0.15,0.28,0.15 ng/mL.方法已用于包头矿分析.