The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
The fluorescent reagent 5-bromo-salicylaldehyde salicyloylhydrazone (5-Br-SASH) was synthesized and its ionization constants were established spectrophotometrically. The fluorescent reaction of this reagent with aluminium was studied. Based on this chelation reaction, a spectrofluorimetric method was developed for the determination of aluminium in acetic acid-ammonium acetate buffer solution of...
A simple and low-cost amperometric sensor for amines has been developed using a cobalt wire electrode working in alkaline solution. The sensor may be used as a detector for high-performance liquid chromatography (HPLC) that avoids the need for derivatization or post-column reaction. Experimental conditions for flow injection analysis (FIA) and HPLC separation, including the applied potential, pH...
The determination of Pt in cordierite is subject to strong interference by spectral overlap from HfO + ions with all Pt isotopes. Two mathematical correction methods based on the HfO + Hf + ratio and a method for the chemical separation of Hf based on adsorption chromatography and isotope dilution were investigated to correct for this interference. Flow infection was used...
A simple, selective and precise voltammetric method for the determination of ascorbic acid in pharmaceutical preparations and fresh fruit juices--complex matrices containing various reducing compounds--is described. The method is based on the electrocatalytic oxidation of ascorbic acid in homogeneous solution using electrogenerated ferriciniumcarboxylic acid as mediator. The pH and mediator concentration...
A spectrophotometric method was developed for the determination of ferbam (iron(III) dimethyldithiocarbamate) by converting it into an iron-phenanthroline complex, which was then absorbed on microcystalline naphthalene in the presence of tetraphenylborate, and the absorbance was measured at 515 nm against a reagent blank. The molar absorptivity of the complex was 1.2 10 4 l mol - ...
The determination of traces of Zn, Pb and Cu in rum samples by anodic stripping voltammetry without previous treatment or addition of a supporting electrolyte, using a hanging mercury drop electrode, is described. The choice of an appropriate stripping voltammetric method and deposition potential minimizes the influence of the organic content and ensures good reproductibility of the measurements...
The development of reference materials to verify the determination of metals in sludge is described. Effluents from domestic and industrial treatment facilities were dried, size-reduced and homogenized. Multiple aliquots of each material were analyzed in two different government laboratories to determine reference values for the acid-extractable concentrations of more than 15 metals. These acid-extractable...
The flame atomic absorption spectrometric determination of copper, zinc, calcium, magnesium and iron in fresh eggs using a microvolume injection technique is described. The capillary tube and glass impact bead were removed from the nebulizer and a polypropylene tube was installed in the inlet of the capillary tube of the nebulizer as the interface for microvolume injection. The injection volume...
Surface-enhanced Raman scattering (SERS) spectrometry of the diuretic drug triamterene is discussed. The SERS-active substrate used is a silver foil etched with nitric acid. The influence of solvent and sample doping method on sensivity, intercept and shape of the calibration graphs is discussed.
The complexation reaction between a macrocyclic polyether, 18-crown-6 (18C6), and potassium ion was studied in methanol (MeOH)-acetonitrile (AN), dimethylformamide (DMF)-AN and propylecarbonate (PC)-DMF binary solvent systems at different temperatures using a conductometric method. It was found that the stability of the 1:1 complex formed between K + ion and this ligand increases with decreasing...
The application of the second-derivative UV spectrophotometry for determining the stability of 3-bromo-N-bromo-N-(3,4-dimethyl-5-isoxazolyl-4-amine)-1,2-naphthoquinone in ethanolic solutions is described. The validity of this method was evaluated using synthetic mixtures of the intact drug and its degradation products and by statistical analysis of the calibration data. In order to verify the usefulness...
The presence of a micellar medium of cetylpyridinium bromide (CPB) causes, in relation to the aqueous medium, important bathochromic shifts in the excitation spectra of a considerable number of polycyclic aromatic hydrocarbons (PAHs). Furthermore, the CPB acts as a quencher, provoking inhibitions of the fluorescence intensity emitted by PAHs. The micellar inhibition factors show that, generally,...
This paper deals with the development and standardization of procedures for the determination of uranium on a routine basis in various process streams of a uranium extraction plant, covering a wide range of concentrations from 350 g l -1 down to 5 mg l -1 using only a spectrophotometric technique. The self-absorption of uranyl ion in dilute phosphoric acid and the violet-blue...
The solubility of 49 metal-containing compounds and 15 free ligands in supercritical fluid carbon dioxide is reviewed. Solubilities were found to range over eight orders of magnitude, with the highest value of solubility being 56 g l -1 . Metals complexed with fluorine substituted ligands were found to be the most soluble, and metals complexed with phenyl-substituted ligands the...
Studies on the determination of trace metallic impurities in nuclear materials such as uranium, thorium and plutonium are described. The bulk of the matrix is separated by batch extraction from their nitric acid solutions using 2-ethylhexyl hydrogen 2-ethylhexyl phosphonate (KSM-17, equivalent to PC88-A). The final aqueous phase containing the metallic impurities is fed to a high-temperature source...
Quantitative structure-activity/property relationships (QSAR/QSPR) studies have been exploited extensively in the designs of drugs and pesticides, but few such studies have been applied to the design of colour reagents. In this work, the topological indices A x1 -A x3 suggested in this laboratory were applied to multivariate analysis in structure-property studies. The topological...
Surfactant aggregates were formed on alumina surfaces by mixing 100 mg of sodium dodecyl sulfate (SDS) and 1.5 g of y-alumina in 50 ml of water. The SDS-coated alumina incorporated water-insoluble metal-ammonium pyrrolidinedithiocarbamate complexes over the pH range 2-8 with a recovery of >97%. The metals were quantitatively desorbed from the alumina with 4 mol l -1 nitric acid,...
A simple, fast and sensitive flow-injection method is proposed for the determination of nanomolar amounts of ascorbic acid in tea, urine and blood. The procedure is based on the accelerating effect of a nanomolar level of ascorbic acid on the reaction of cooper(II) with 5,10,15,20-tetrakis(1-methylpyridinium-4-yl)porphyrin, H 2 tmpyp 4+ . Ascorbic acid reduces Cu(II) to Cu(I)...
The use of 85% phosphoric acid in borosilicate conical flasks for the dissolution of ilmenites at 230 ± 10°C is reported. The samples were quantitatively dissolved in less than 13 min. Titanium was determined by both spectrophotometry and inductively coupled plasma atomic emission spectrometry ICP-AES. Vanadium and iron were determined by ICP-AES. In several samples of ilmenites analyzed, the...
The possibility of the utilization of the copper(II)-neocuproine spectrophotometric method, which has previously been shown to permit the determination of various reducing agents, to the determination of vitamin E was investigated. The molar absorptivity for vitamin E was found to be (2.1 ± 0.1) 10 4 l mol -1 cm -1 and Beer's law was obeyed between 2.4 10 ...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.