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A polystyrene divinyl benzene based resin containing bicine groups has been prepared and its analytical properties investigated. The pH dependence of sorption of metal on the resin has been determined for Cu(II), Fe(II), Ni(II), Co(II), Zn(II), Hg(II) and Pb(II). The important characteristics of the resin are fast equilibrium, high selectivity and small volume change between its hydrogen and metal...
Solver, an analysis tool incorporated into Microsoft Excel V 5.0 for Windows, has been evaluated for solving non-linear equations. Test and experimental data sets have been processed, and the results suggest that solver can be successfully used for modelling data obtained in many analytical situations (e.g. chromatography and FIA peaks, fluorescence decays and ISE response characteristics). The...
The complexation of urea (ur) with manganese(II), nickel(II) and zinc(II) ions has been studied by titration calorimetry in N,N-dimethylformamide (DMF) containing 0.4M (C 2 H 5 ) 4 NBF 4 as a constant ionic medium at 25°C. The calorimetric data were well explained in terms of the formation of [Mn(ur)] 2+ , [Mn(ur) 2 ] 2+ and [Mn(ur)...
A new method has been developed for the spectrophotometric determination of l-dopa in pharmaceutical formulations. The method is based on the reaction between the open-chain quinone ofl -dopa, obtained in NaOH, and the benzoqinoneimine form of p-aminophenol, in the presence of KIO 4 . The reaction product is determined at 574 nm by using both alternately procedures, one based on the stopped-flow...
Fast heating programmes for determining aluminium and chromium in vegetables using electrothermal atomic absorption spectrometry with slurry sampling are developed using wall atomization. The build-up of carbonaceous residues inside the atomizer is avoided by adding 4% hydrogen peroxide and 1% nitric acid to the slurries instead of using an air-ashing stage. In accordance with fast-programme methodology,...
A new analytical method was developed for the determination of ascorbic acid. The method is based on the reaction of ascorbic acid with 4-chloro-7-nitrobenzofurazane (NBD-Cl) in the presence of 0.2M sodium hydroxide, where a bluish green colour (λ max 582 nm) is developed after dilution with 50% (v/v) aqueous acetone solution. Beer's law was obeyed in a concentration range of 5-20...
The light originating from seven light-emitting diodes of different colours is guided, one at a time, into a measuring cell by means of a fibre optic coupler. Detection is carried out with photodiodes which are connected to a log-ratio amplifier yielding direct absorbance readings. Optical filters are used to narrow the emission band from blue light emitting diodes as these bands are relatively...
An efficient, real-time chemiluminescence detector for hydrazine vapor, N 2 H 4 (g), is described, capable of monitoring sub part-per-billion levels of hydrazine in air. The catalytic oxidation of hydrazine by colloidal platinum forms an intermediate, oxidizing agent (e.g. . OH or . OOH) which subsequently oxidizes luminol, generating a chemiluminescence signal that...
A new method for the determination of 2-thiobarbituric acid, using its reaction with iodine in an alkaline medium is presented. In the volumetric titration with potentiometric end-point detection, the determinability range is 10-400 μmol (1.4-58 mg). In coulometric titration using the biamperometric end-point detection, 0.1-20 μmol (1.4 10 -2 -2.9 mg) of 2-thiobarbituric acid was...
A cationic exchanger paper is used to retain analytes in solution and, after drying, to analyze directly by measuring the UV-Vis absorbance of the paper. The method was applied to determination of iron using its known 1,10-phenanthroline complex. Using 100 ml of sample the applicable concentration range was between 1.0 and 10.0 ng/ml with a detection limit of 0.2 ng/ml and a RSD around 2%. The...
In order to determine the fate of the herbicides atrazine (as well as some of its degradation products) and metolachlor in water and sediments, a method was developed to extract and analyse these compounds. The two matrices were separated completely by centrifugation followed by filtration using nylon filters (0.45 μm). Sediments were extracted with a mixture of methanol-0.1N hydrochloric acid (50:50,...
Electrochemical behaviour of some naturally occurring hydroxy derivatives of 9,10-anthraquinone such as chrysophanic acid (Ch), rhein (Rh) and emodin (Em) at mercury and glassy carbon electrodes using two different supporting electrolytes in chloroform is described. In the presence of piperidinium perchlorate (0.75M) + piperidine (0.25M) as a suitable acid supporting electrolyte, the reduction of...
S9788 is a novel triazinodiaminopiperidine derivative which reverses the multidrug resistance of tumour cells to anticancer drugs. In this study, a new HPLC method was developed to determine this compound in P388 leukaemia cells. The influence of various parameters (composition and pH of the mobile phase, nature of the column) on the separation of S9788 and derivatives was investigated. Using a...
The spectrophotometric determination of pyridine and pyridine derivatives by means of the Konig reaction was studied in micellar media of sodium dodecyl sulphate (SDS), N-cetylpyridinium chloride and Triton X-100. The sensitivity was largely increased in SDS micellar medium. The attack of the pyridine ring with cyanogen bromide to produce a glutaconic aldehyde was not affected by the presence of...
A reversed phase ion pair chromatographic method for the simultaneous determination of Cr species and common anions on a C 18 -bonded stationary phase was developed by using acetonitrile-water (2:98 v/v) containing 1.0 mM tetrabutylammonium hydroxide and 0.5 mMtrans -1,2-diaminecyclohexane-N,N,N ,N -tetraacetic acid (DCTA) at pH 6.5 as mobile phase and UV-detection at 210 nm. Chromatographic...
A flexible pervaporation module was developed and characterized. The spacers it uses allows the volume of the donor and/or acceptor to be altered as required. The performance of the module was tested as regards both dynamic behaviour and continuous pervaporation in terms of flow-rates, temperature, type of membrane, flow mode, etc. A method for the determination of ethanol in different types of...
A flow injection on-line microcolumn method has been studied for the separation and preconcentration of noble metals, Pd, Pt and Ir, followed by flame AAS determination. An α-amino pyridine resin was used as preconcentration reagent. Non-noble metals studied could be eliminated by 2M HCl solution in the rinsing stage. A group-eluent for all Pd, Pt and Ir was studied. Separation of individual noble...
A β-diketone-imbedded polyurethane foam was made for the sorption of uranium from aqueous solutions. The incorporation of the β-diketone functional group into the polyurethane foam was simple, and relatively inexpensive. The β-diketone foam was ground to facilitate the evaluation of its ability to extract uranium from aqueous solutions with a wide range of temperature and pH values. The β-diketone...
A factorial composite design was employed for the exploration of the response as a function of the flow rate and length of the dispersion coil of a flow injection system employed for on-line dilution and determination of copper by flame-AAS. For this purpose, an empirical response function (RF), which takes into account the peak height and the response time, was employed to evaluate the response...
The phase-inversion (PI) method was used to cast permselective cellulose acetate membranes on glassy carbon electrodes with the aim of suppressing protein interferences in anodic stripping voltammetry (ASV). By using cadmium and lead as test analytes and differential pulse ASV as detection method, it was found that the modification of the electrode greatly reduces the interference from albumin. ...
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