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An extraction-spectrophotometric method for the determination of phenytoin in capsules and plasma is presented. The method is based upon oxidation of phenytoin using alkaline potassium permanganate solubilized in chloroform/cyclohexane (1:1) after crowning with dicyclohexano-24-crown-8 (DC-24-C-8). The formed benzophenone being soluble in the oxidation reaction medium was directly measured at 238...
A new concentration method of rhodium using Mg-W cell-electrodeposition has been developed. The method was combined with electrothermal atomic absorption spectrometry (ETAAS) with a tungsten tube atomizer. The optimal immersing time was 120 s. The most suitable pH for rhodium electrodeposition was 1.0. Under optimal conditions, the detection limit of rhodium by the ETAAS with the preconcentration...
A sensitive method is described for the determination of ofloxacin in its pure form, dosage forms and biological fluids. The proposed method depends upon the polarographic activity of ofloxacin in Britton Robinson buffers, whereby a well-defined cathodic wave is produced over the pH range 4.1-10.3. The wave was characterized as being irreversible, diffusion-controlled with limited adsorption properties...
With the aim of carrying out a calibration transfer for routine analysis, partial least squares (PLS) regression was successfully applied to simultaneously determine thallium and lead by stripping voltammetry when an interfering background current is present. The presence of a significant blank signal that overlaps the thallium peak, together with the overlapping thallium and lead signals were both...
An investigation of chemiluminescence (CL)-emission generated by the oxidation of pyrogallol using various inorganic oxidant compounds is reported in this F.I.A.-merging zone application. The oxidant compounds that showed measurable CL-emission were permanganate, periodate, hypochlorite anions, cerium(IV) and hydrogen peroxide. The different oxidant compounds showed CL-emissions at different pH-ranges...
The behaviour of taurine as a ligand (L) towards silver(I) and cadmium(II) was studied at 25 o C and in 1 mol dm -3 NaClO 4 , as a constant ionic medium. Experimental data, obtained for both cations from electromotive force measurements performed by using silver and cadmium amalgam and glass electrodes, were explained by assuming the formation of the AgL, AgL 2 ...
The stability constants of Fe(II), Co(II) and Cu(II)-NTA-penicillamine were determined by paper electrophoresis. The values of these constants were found to be 5.06, 5.16 and 5.28 (log K values), respectively at μ=0.1 and 35 o C.
The solubility of Ba(IO 3 ) 2 has been determined in solutions containing a supporting electrolyte (KCl) to maintain the ionic strength in the 0-0.5 M range. The approach envisaged was based in the amperometric determination of iodine (or triiodide) generated in the reaction involving iodate in equilibrium in the saturated solutions and iodide contained in the solution carrier using...
An anion-exchange fast protein liquid chromatographic-inductively coupled plasma atomic emission spectrometric procedure (FPLC-ICP-AES) was developed for speciation of Al-citrate and other negatively charged Al complexes. FPLC separations were carried out on a Mono Q HR 5/5 strong anion-exchange FPLC column over a pH range from 3.5 to 11.0. An aqueous-NaNO 3 (4 mol dm -3 ) linear...
This paper reports an investigation on optimal separation and detection for animal prostaglandins, i.e. prostaglandin E 2 (PGE 2 ) and thromboxane B 2 (TXB 2 ) by capillary zone electrophoresis with indirect detection at 254 nm. It was found that the addition of 3 mmol l -1 phosphomolybdic acid in 5 mmol l -1 chromate buffer can lower the detection...
Simple and sensitive spectrophotometric methods are described, for the first time, for the determination of sodium salts of phenobarbital (1), thiopental (2), methohexital (3) and phenytoin (4). The methods are based on the reaction of these drugs as n-electron donors with the σ-acceptor iodine and various π-acceptors: 7,7,8,8-tetracyanoquinodimethane; 2,3-dichloro-5,6-dicyano-1,4-benzoquinone; 2,3,5,6-tetrachloro-1,4-benzoquinone;...
An alternative method for the determination of the concentration of diethylenetriamine (DETA) in aqueous mineral flotation solutions is described. This method is based on the formation of a DETA-Ni(II)-sulphite complex, which shows a UV absorption maximum at 285 nm that varies linearly with the concentration of DETA throughout the 0-50 mg l -1 DETA range. A high concentration of Ni(II)...
Two simple, rapid and sensitive spectrophotometric methods for the determination of catecholamine derivatives (pyrocatechol, dopamine, levodopa and methyldopa) are developed. The first method involves the oxidation of o-dihydroxybenzene derivatives by N-bromosuccinimide followed by oxidative coupling with isoniazid leading to the formation of a red-coloured products of maximum absorbance (λ m...
A new simple, selective and sensitive fluorescence quenching method was developed to determine chromium with rhodamine 6G. The method is based on the oxidation of rhodamine 6G by chromium(VI) in sulfuric acid solution. The linear calibration graph was obtained in the range 8-80 ng ml -1 chromium(VI). The detection limit is 0.8 ng ml -1 . The method was applied successfully...
In this paper, separations of organic compounds, such as, n-alkanes, alcohols, ethyl asters of C 1 -C 8 carboxylic acid, halogen derivatives, position-isomers of the replacement aromatic hydrocarbon, optical isomers of ethyl lactate and isoamyl alcohol, etc. were studied using 4'-cholestenoxycarbonyl-benzo-15-crown-5 liquid crystal crown ether (CH-B-15-C-5) as stationary phase in gas-solid...
A simple, inexpensive, on-line bulk acoustic wave (BAW) DNA biosensor is proposed by using an Ag-plated surface rather than the conventional Au surface. Bovine serum albumin (BSA) is used as an active coating for DNA immobilization. Impedance analysis reveals that the film composed of didodecyl dithiono-oxamide (DDDTO) and BSA can dramatically enhance the amount of immobilized DNA. Detection of dissociation...
The reaction between hexacyanomanganate(IV) and hydrogen peroxide in acidic medium is strongly catalysed by vanadium. The stoichiometry has been proved to be Δ[Mn(IV)]/Δ[H 2 O 2 ]=1. S-shaped absorbance-time curves are obtained for a wide range of conditions, which seems to be due to the transient formation of hydroperoxyl radicals, HO 2 .; therefore, the reaction is autoinduced...
N-n-Octylaniline in xylene is used for the extractive separation of palladium(II) from hydrochloric acid medium. Palladium(II) was extracted quantitatively with 10 ml of 2% reagent in xylene from 0.5-2 M hydrochloric acid medium. It was stripped from the organic phase with 1:1 ammonia and estimated spectrophotometrically with pyrimidine-2-thiol at 420 nm. The effects of metal ion, acids, reagent concentration...
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