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A new technique for the determination of low molecular weight organic acids in Bayer process liquors is reported. The acids are partitioned from acidified liquor into butanol, followed by butylation using microwave heating. This method is both rapid (sample preparation time < 15 min) and capable of detecting acids larger than previously reported in the low molecular weight fraction (up to RMM...
A modified computer program SCTPT for the computation of formation constants of extraction complexes with two-phase pH titration data by using the Marquardt-Fletcher algorithm is described. It can be used to deal with extraction systems which consist of a metal, an acidic extractant and a neutral synergistic reagent with no need of new subroutine. It has been applied successfully to the Pb-PMBP(1-phenyl-3-methyl-4-benzoyl-pyrazolone-5)-TBP...
A reasonably sensitive and highly selective spectrophotometric method for the determination of mercury(II) is proposed. The method is based on the extraction of the ion-associate formed by a mercury(II) thiacrown ether cationic complex with Bromocresol Green as the anionic counter-ion using chloroform as the extracting solvent. The effect of thiacrown ethers of different cavity sizes, namely 1,4,7,10,13-pentathiacyclopentadecane...
A sensitive, direct spectrofluorimetric method for the trace determination of terbium with use of trimesic acid (TMA) has been developed. The reaction conditions for the fluorescence system of terbium with TMA were studied. The terbium ion can form a stable binary chelate with TMA, having a ratio of 1:1 in the pH range 3.5-6.5. The maximum excitation and emission wavelengths are 260 nm and 545...
Three simple and sensitive spectrophotometric methods for the determination of tamoxifen citrate have been developed. They are based on the formation of an ion-association complex between the drug and a dye, Erioglaucine A, which is extractable into chloroform and has an absorption maximum at 625 nm (method A), oxidation with excess potassium permanganate and the determination of unconsumed permanganate...
Room-temperature phosphorescence characteristics of serotonin (5-hydroxytryptamine), typtamine, and gramine ([3-(dimethylaminomethyl)indole]) were studied on low-background paper substrates. Several experimental parameters were optimized for maximum signal intensity. Sodium iodide, thallium(I) nitrate, silver(I) nitrate, and lead(II) nitrate were tested as phosphorescence enhancers. The effect...
A method for the preconcentration of trace amounts of tungsten as its thiocyanate complex, using a column filled with Amberlite XAD-1180 resin, is proposed. After elution with a small volume of acetone, the analyte was determined spectrophotometrically with potassium thiocyanate and stannous chloride. The influence of several ions, as interferents, is discussed. The proposed method was applied to...
Chromatographic systems for the separation of amino acid mixtures on RP-18 as a stationary phase have been elaborated. The best results were obtained using methanol-water (1:1, v/v; 1:3, v/v; 1:5, v/v) as a mobile phase.The following amino acids have been examined: asparagine, arginine monohydrochloride, cystine, cysteine chloride, glycine, histidine monohydrochloride, hydroxyproline, isoleucine,...
Flow-injection analysis for the determination of hydrazine derivatives based on their nucleophilic substitution reaction with 4-chloro-5,7-dinitrobenzofurazan in aqueous medium, and spectrophotometric detection has been described. The calibration graphs were linear in the range from 0.15 to 4.0 μg ml -1 of hydrazine derivatives, with sampling rates of up to 28-32 samples h - ...
A method for the determination of salbutamol in both tablets and syrups is described. It utilizes the reduction of the Folin-Ciocalteau reagent by the phenolic group, monitoring the absorbance of the resulting complex at 760 nm. Results obtained are linear over the range 0-6 μg ml -1 salbutamol. Coloring material was removed by anionexchange chromatography prior to analysis and there...
A new combination of a flow/sequential injection method for the analysis of ammonia has been developed. Gaseous ammonia is selectively absorbed in a phosphoric acid coated glass tube and determined with Berthelot reagents by flow injection. The combination of the gas diffusion denuder sampler with flow injection makes this method very sensitive and selective. The limit of detection of 0.15 μg NH...
A new method is proposed for the solvent extraction separation of cobalt(II) with hexaacetatocalix(6)arene in toluene. Cobalt(II) was extracted at pH 7.4 with 10 10 -4 M hexaacetocalix(6)arene, stripped with 2 M nitric acid, and determined spectrophotometrically at 500 nm as its complex with nitroso-R-salt. Cobalt was separated from any associated elements. The method was extended...
This paper reports the concentration of some dissolved organic phosphorus insecticides in water by open-cell polyurethane foam. The results of preliminary screening tests on the retention of the tested insecticides (Diazinon, Malathion and Chloropyrifos) by polyester foams indicated that a very high percent removal of the insecticides was obtained. The retention rate was fast and reaches equilibrium...
In this paper two simple configurations for sample illumination using a charge-coupled device (CCD) detector have been shown. The choice of an appropriate sample illumination can be crucial to obtain spatial and spectral information of complex samples. It is demonstrated that simultaneous Raman spectra of a heterogeneous sample of three compounds can be obtained using a vertical sample illumination...
A new method for determining 34 S: 32 S ratios using Fourier transform infrared spectroscopy has been developed. The four sulphur-containing gases SCO, H 2 S, SF 6 and SO 2 are assessed as possible compounds for the spectroscopic measurements, from which, after a consideration of available lines showing a clear isotopic shift and also of possible...
The polarographic and voltammetric behaviour of the copper(II)-mitoxantrone complex have been studied. A well-defined linear sweep voltammetric peak was obtained at -0.275 V (vs. Ag/AgCl) or -0.325 V (vs. SCE) in ammonia-ammonium chloride (20 mmol l -1 , pH 9.0). The characteristics of the peak have been examined in detail. The experimental results show that the reduction of the copper(II)...
A novel glassy carbon electrode design, permitting medium exchange in batch mode without loss of electrode potential control, has been used for the study of copper(I) and copper(II) species formed during constant current stripping oxidation of copper in chloride media. It was found that copper(II) species dominated at chloride concentrations below about 1 mM and that soluble copper(I) species dominated...
Macrolide antibiotics such as erythromycin, oleandomycin, spiromycin, and tylosin are found to react with Fe 3+ in the presence of an acetic acid-sulfuric acid mixture to form a colored product having a useful absorption band at 592 nm. Troleandomycin forms only a weakly colored product upon reaction. The molar absorptivity is about 2900 1 mol -1 cm -1 for...
Two novel biosensors for urea based on immobilized corynebacterium glutamicum 617 and corynebacterium glutamicum ATCC13032 in calcium alginate gel coupled with an ammonia gas-sensing electrode, were designed and constructed. Calibration plots of measured potential difference (mV) vs. log of urea concentration were linear in the range of 5.6 10 -5 - 1.4 10 -2 and 5...
A fractal analysis is presented for the binding of pyrene in solution to β-cyclodextrin attached to a fiber-optic chemical sensor. The specific (k 1 ) and non-specific binding rate coefficients and the fractal dimension (D f ) (specific binding case only) both tend to increase as the pyrene concentration in solution increases from 12.4 to 124 ng ml -1 . Predictive relations...
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