Talanta
The protonation constants, K r , for the ligands succinic acid (SA), mono-methyl succinate (MS) and propionate (PA) have been determined, at 25°C, by glass electrode potentiometry in 3 mol/dm 3 (M) NaNO 3 , KNO 3 , NH 4 NO 3 , Ca(NO 3 ) 2 and Et 4 NBr aqueous media. Results are compared with literature constants determined in...
The equilibrium extraction behaviour of Gd(III) using a chloroform/kerosine solution containing di(2-ethylhexyl)phosphoric acid (HDEHP), either alone or combined with one of three adductants, 1,10-phenanthroline monohydrate (phen), α,α -dipyridyl(2,2 -bipyridine) (bipy) or trioctylphosphine oxide (TOPO) is described. The enhancement of the extraction by addition of such neutral adductants is explained...
In a novel approach to the use of macrocycles in separation systems, we report the use of macrocyclic ligands as electroosmotic flow modifiers for the separation of inorganic anions by capillary electrophoresis (CE). Inorganic anions were successfully separated through the use of 18-crown-6 or cryptand 2.2.2. as electroosmotic flow modifiers. We found that for our CE system, use of a macrocycle as...
A simplified approach to the correction of equilibrium constants from one ionic strength and/or medium to another is developed. A computer program capable of performing these calculations is presented together with results of its application to the NH 3 H + ,CH 3 COO - H + ,CH 3 CH 2 COO - H + ,-OOCCH 2 COO - ...
A highly selective, sensitive and rapid differential pulse polarographic method (DPP) has been developed for the simultaneous estimation of trace amounts of lead and cadmium in standard alloys, biological and environmental samples. The morpholine-4-carbodithioates of the samples were absorbed on microcrystalline naphthalene in the pH range of 5-10 for lead and 3.4-11 for cadmium. The metal complexes...
Four tetrols of benzo[a]pyrene-DNA adducts were separated using reversed-phase high performance liquid chromatography. Chromatographic fractions containing a given tetrol were readily characterized with solid-matrix room temperature luminescence techniques. Solid-matrix fluorescence and phosphorescence spectra at picogram amounts of a tetrol were easily obtained. Tetrol fractions collected based...
Gallium chloride is easily extracted from 6M HCl by comminuted polyether-type polyurethane foam. After the extraction step, the gallium absorbed by the PU foam can be quantitatively determined by X-ray fluorescence. A procedure for the direct determination of gallium absorbed by PU foam by XRFS is thus described. Gallium is determined at levels as low as 60 ng/ml (C L ), with a calibration...
The feasibility of utilizing a zwitterionic surfactant, 3-(nonyldimethylammonio)propylsulfate, or nonionic surfactant, Triton X-114, mediated phase separation in conjunction with affinity ligands was studied for hydrophilic protein extractions. Below (or above) its critical temperature (so-called cloud point), aqueous solutions of zwitterionic (or nonionic) surfactants separate into two immiscible...
The use of 4-aminoantipyrine for the colorimetric determination of propoxur in pesticide formulations and water samples is described. The method is based on the alkaline hydrolysis of the pesticide and the resultant phenol is reacted with 4-aminoantipyrine in the presence of an oxidizing agent. The resultant colored dye is extracted into chloroform and the absorbance measured at 472 nm.
An extraction procedure based on cloud point phase separation of nonionic surfactants was used to remove oil contamination from soils. The detergent employed was Triton X-114, and its clouding behavior was monitored by means of a fluorescence probe. Changes in the I 1 /I 3 ratio of pyrene indicated gradual dehydration of the detergent micelles upon heating. The rate of phase separation,...
A sensitive spectrophotometric method has been developed for the determination of ziram in water, vegetables and grains. The method is based on the dissociation of dithiocarbamate complex of zinc with thiocyanate and rhodamine 6G at pH 4 to form a pink coloured complex that is stabilized by gelatin. The method is simple and Beer's law is obeyed over the concentration range of 0.05-1 ppm of ziram...
The use of two-phase potentiometric metal extraction titrations to study solvent extraction equilibria is described. The method provides a highly reproducible and convenient manner by which to determine extraction behaviour. The system was tested on a number of acidic extractants, namely D2EHPA, Ionquest 801, Cyanex 272, naphthenic acid and Versatic 10 acid. The extraction from an aqueous nitrate...
Spectrophotometric determinations of benzoylperoxide (BPO) and copper(II) were, respectively, investigated by using the colour reaction for N-ethyl-2-naphthylamine (NENA), BPO and copper(II) as a metal ion in various concentrations of acetonitrile-water mixed solution as acidic media. The calibration graphs were linear in the range of 0-200 μg BPO with apparent molecular coefficient ( ) of 8.5 ...
Hydrogen atoms form two kinds of adducts with thymine (oxidizing and reducing). Redox reactions of these two kinds, popularly known as 5-hydrogenated-6-thyminyl (reducing) and 6-hydrogenated-5-thyminyl (oxidizing), were investigated where ferric ions (oxidizing) and ferrous ions (reducing) were used as the corresponding redox partners. A steady-state gamma radiolytic system was chosen where hydroxyl...
Binary mixtures of pyridoxal and pyridoxamine can be resolved by using zero-crossing first derivative spectrofluorimetry, first derivative constant wavelength synchronous luminescence spectrometry and first derivative constant energy synchronous luminescence spectrometry. These methods do not require any previous separation steps. The lowest quantization limit is obtained with first derivative constant...
A sensitive spectrophotometric method was established for the determination of Diclofenac sodium (DS) with Methylene Blue (MB) as analytical reagent. It was found that DS reacts with an excess of MB in the pH range 9.2-9.4, to form a chloroform-extractable blue ion-association complex. Good agreement with Beer's law was found in the range of DS concentrations of 0.8-6.4 μg/ml with a detection limit...
Aided by the construction of a custom potentiostat, a series of different PAD waveforms were compared to find the optimum detector for penicillin oxidation. The waveforms included standard 3-step direct and indirect PAD in addition to reverse-PAD and 4-step PAD. Two new waveforms, the indirect reverse-PAD and the 4-step indirect PAD were examined in the study. Under the solvent conditions of the...
A method for the precise coulometric titration of platinum(IV) with electrogenerated chlorocuprous ion in KCl-Cu-EDTA buffer medium is described. From 2.7 to 18.7 mg of platinum in pure platinum and platinum alloy are determined with standard deviations of less than or equal to 0.034% using potentiometric end point detection. The method has good accuracy and precision, selectivity and rapidity.