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A reversed phase ion-paired chromatographic method that can be used to determine trace amounts of iron (II,III), nickel (II) and copper (II) was developed and applied to the determination of iron (II) and iron (III) levels in natural water. The separation of these metal ions as their 4,7-diphenyl-1,10-phenanthroline (bathophenanthroline) chelates on an Inertsil ODS column was investigated by using...
Volume corrections in calculation of equilibrium state for multi-phase systems, as an extension from one-phase systems, have been described. The algorithms can handle with one, two, three or more phases of different volumes. Several applications of the algorithms to calculation of equilibrium concentrations of all species in two- and three-phase systems have been presented. Different possibilities...
A new crown hydroxamic acid, 5,14-N,N -hydroxyphenyl-4,15-dioxo-1,5,14,18-tetraaza hexacosane (NHDTAHA) for the extraction and spectrophotometric determination of lanthanum(III) is described. Lanthanum(III) forms a yellow coloured complex with NHDTAHA, which is extracted with chloroform, having molar absorptivity 7.7 10 3 l mol -1 per cm at 372 nm. The system obeys Beer's...
Some podands, acyclic polyethers, were utilized as membrane active components to prepare Ag + -selective polymeric membrane electrodes. The thiapodand-based electrodes exhibited considerable selectivity toward Ag + over other heavy metal ions including Cd 2+ , Pb 2+ , Cu 2+ and Hg 2+ . Also, good selectivity over alkali and alkali...
A method for the determination of sulfide based on the addition reaction of sulfide with magenta at pH 7 and 25°C is described. The decrease in absorbance of magenta at 540 nm, its λ max , over a fixed time is proportional to the concentration of sulfide over the range of 25-2500 ng ml -1 . The limit of detection was found to be 15 ng ml -1 . Ten replicate...
It is well known that alterations of the times and potentials of each step within a PAD waveform can alter the sensitivity of the amperometric response, peak shape has also been found to vary with waveform adjustments. This work studied the variation in both peak heights and peak tailing as a function of waveform alterations for penicillin G oxidation in flow injection analysis. Large variations...
The complex-formation equilibria of dimethyltin(IV), trimethyltin(IV) and tributyltin(IV) with pyridoxamine were investigated in dioxane-water mixtures and at different temperatures using a potentiometric technique. The stepwise formation constants of the complexes formed in solution were calculated using the non-linear least-square program MINIQUAD-75. The effect of dioxane as a solvent on the protonation...
Four simple and sensitive methods for the assay of omeprazole (OMZ) were developed. These methods are based on the formation of colored species by treating OMZ with 3-methyl-2-benzothiazolinone hydrazone (MBTH) following oxidation with ferric chloride (method A) or m-aminophenol following oxidation with chloramine-T (CAT) (method B) or Folin-Ciocalteau reagent (F-C) (method D), or by oxidizing OMZ...
Two membrane inlet mass spectrometric (MIMS) methods for determining phenolic compounds in water are described and compared, namely direct analysis and analysis after acetylation of the phenolic compounds. Direct analysis of phenolic compounds in water is a very simple and rapid method and detection limits are relatively low (from 30 μg l -1 for phenol to 1000 μg l -1 for...
A highly water soluble disulfonated tetrazolium salt, 4-[3-(2-methoxy-4-nitrophenyl)-2-(4-nitrophenyl)-2H-5-tetrazolio]-1,3-benzen e disulfonate sodium salt, was synthesized. The compound is reduced by NADH in good yields at neutral pHs in the presence of 1-methoxy PMS to produce the corresponding formazan dye that absorbs at 460 nm. The formazan is soluble to water at concentrations higher than...
Liquid-liquid extraction separation of iron(III) with 2-ethyl hexyl phosphonic acid mono 2-ethyl hexyl ester (PC-88A) in toluene has been studied. Quantitative extraction of iron(III) with 5 10 -3 M PC-88A in toluene is observed in the pH range 0.75-2.5. From the extracted complex species in the organic phase iron(III) was stripped with 1-4 M HNO 3 , 1.5-4 M H 2 SO...
An optical chemical sensor has been prepared for the selective determination of o-nitrophenol in aqueous solutions based on the fluorescence quenching of curcumin in PVC membrane. The sensing mechanism of the proposed sensor for o-nitrophenol has been discussed in detail. The fluorescence changes of sensing membrane resulted from an associated complex formation between curcumin and o-nitrophenol...
The procedure of hafnium determination in workplace air has been elaborated, which allows its determination at the level starting from 0.125 mg m -3 , which for a 400 1 sample corresponds to the requirement for maximal allowable concentration. The method is based on excitation of the mineralized filter containing the analyte in inductively coupled plasma.
Analysis of the total antimony in plant material was unsuccessful using the electrothermal atomic absorption spectrometry (ETAAS) conditions recommended by the instrument manufacturer. For this reason, an optimisation procedure utilising the Plackett-Burman method, simplex optimisation and visualisation of the generated response surface via principal components analysis, was carried out. The Plackett-Burman...
The ion exchange behavior of Au and Pt on a new China-made macropore anion resin was studied using radiotracer technique. The conditions for adsorption and desorption, such as acidity, flow-rate and concentration of desorbing agents were studied carefully. Using the established method, the contents of Au and Pt in two Chinese ultrabasic SRMs were determined by ICP-MS and the results found in good...
A simple and very sensitive kinetic fluorimetric method is reported for the determination of trace amount of thiocyanate. The proposed method is based on the inhibition effect of thiocyanate on oxidation of rhodamine 6G by potassium bromate in sulfuric acid solution. The detection limit for thiocyanate is 1.63 10 -6 mmol/l. The linear range of the determination is 4.82 10 ...
A precise and accurate graphite furnace atomic absorption spectrometric method for the determination of mercury in urine was developed. Samples were subjected to hydrolysis with nitric acid. Then, mercury in the sample was complexed by dithizone and extracted by cyclohexane. Mercury concentrations were determined against a urine-matched calibration curve. Coated graphite notched partition tubes...
A method was developed for the recovery and determination of cyanide ion in organic sample matrices. To facilitate the solubilization of cyanide ions, cetyltrimethylammonium bromide (CTAB) was added at concentrations above the critical micelle concentration. Sample cyanation reaction products consisted of solvent mixtures of a hydroxynitrile in DMF-toluene or DMF-isopropylacetate (IPAC). Spectrophotometric...
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