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The determination of manganese in the presence of iron and chromium by differential pulse voltammetry and fundamental harmonic alternating current voltammetry was compared, including the case of very high element concentration ratios. The voltammetric measurements were carried out using a stationary mercury electrode in ammonia-ammonium chloride buffer (pH 9.6). The analytical procedure was verified...
A solid ion-pair material produced from ammonium tetraphenylborate on naphthalene (ATPB-naphthalene) provides a simple, rapid, economical and selective technique for preconcentrating iron from 500 ml of aqueous solution of standard alloys and biological samples. Iron reacts with 2-(5-bromo-2-pryidlazo)-5-diethylaminophenol (5-Br-PADAP) to form a water-soluble cationic complex. When the aqueous...
A method is proposed for the simultaneous determination of iron(III) and molybdenum(VI) by first-derivative spectrophotometry based on the absorption spectra of their complexes with morin in the presence of a cationic surfactant. The zero-crossing measurement technique is found suitable for the direct measurement of the first-derivative value at the specified wavelengths. Iron(III) (0.9-1.5 μg ml...
A highly sensitive and selective voltammetric procedure is described for the determination of trace amounts of iron. The procedure is based on the adsorptive collection of an iron-thiocyanate-nitric oxide complex on a hanging mercury drop electrode. The adsorbed complex catalyzes the reduction of nitrite in solution, which gives a detection limit of 40 ppt iron (30 s accumulation). The stripping...
The design and use of a two-channel fountain cell in potentiometric and voltammetric detection is described. The two flows produced two distinct sectors inside the thin layer region and one of the sectors was used as the internal electrolyte of a reference electrode built into the cell body and the other as the indicator/counter electrode section. The behavior of the flowthrough Ag/AgCl reference...
A lot of modern analytical strategies for exploiting chemistries have been developed by using flow-injection analysis. However, even after 20 years of flow-injection evolution, there still are new quantitative procedures being established using old qualitative assays. The formation of Prussian Blue is a classical test to detect Fe 2+ using hexacyanoferrate(III) as a precipitating reagent....
A flow injection analysis (FIA) method is presented for the simultaneous determinations of iron(III)-vanadium(V) and of iron(III)-chromium(VI) using a single spectrophotometric detector. In the presence of 1,10-phenanthroline (phen), iron(III) is easily reduced by vanadium(IV) to iron(II), followed by the formation of a red iron(II)-phen complex (λ max =510 nm), which shows a positive...
Ultrafiltration has been used to examine the size fractionation of lead, copper, iron, aluminium, calcium, potassium and sodium in white and red wines. Fractionation patterns demonstrated that the behaviour of lead is significantly different to the other metals considered. In red wine, there was a sudden decrease for lead between 100 000 and 30 000 nominal molecular weight cut off (NMWCO) and in...
Two methods for the determination of iron by normal FIA and reversed FIA were developed using sodium 3-(2-pyridyl)-5,6-diphenyl-1,2,4-triazine-4′,4″-disulphonate (ferrozine). The reagent formed a chelate with Fe(II) in hexamethylentetramine buffered medium at pH 5.5. In one previous reaction coil Fe(III) was reduced to Fe(II) by ascorbic acid and in the other reaction coil the complexation reaction...
A highly sensitive and selective second derivative spectrophotometric method has been developed for the determination of copper and iron in mixtures. The method is based on the separation of the analytes by liquid-liquid extraction as picrate ion pairs. Iron-picrate, reacts in the organic phase of DCE with 5-phenyl-3-(4-phenyl-2-pyridinyl)-1,2,4-triazine (PPT). Similarly the copper-picrate reacts...
A module for continuous high pressure-temperature leaching is proposed. The overall approach involves the coupling of an extractor with a continuous-flow manifold where the analyte forms a complex with SCN - , which is driven to a flow-cell packed with a suitable material for retention and continuous monitoring of this process which in turn is a way for indirect monitoring of the leaching...
A flow-injection method for the simultaneous determination of iron and zinc in the human hair with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) using a pH gradient technique has been developed. The linear range for the determination of iron is 0.1∼1.8 μg ml −1 and for zinc is 0.2∼5.0 μg ml −1 . About 20∼30 samples can be determined in 1 h. The proposed method is simple,...
A method for the simultaneous spectrophotometric determination of the divalent ions of iron, cobalt, nickel and copper based on the formation of their complexes with 1,5-bis(di-2-pyridylmethylene) thiocarbonohydrazide (DPTH) is proposed. The resolution of quaternary mixtures of these metallic ions was accomplished by several chemometric approaches. A comparative study of the results obtained for simultaneous...
A flow system exploiting multicommutation and multidetection is proposed for sequential determinations in pharmaceutical preparations. The feasibilities were demonstrated by the determination of zinc, iron, copper, calcium and magnesium without changing the flow set-up. The gravitational flow of the solutions was exploited for addition of different chromogenic reagents and sample aliquots, thus avoiding...
The present work describes an alternative technique for monitoring the rate of oxygen consumption during the oxidation of HSO 3- catalyzed by manganese and iron ions. The method is based on the spectrofluorimetric monitoring of the quenching effect of molecular oxygen on the emission of the photoexcited [Ru(bipy) 3 ] 2+ ion, added to the reaction mixtures. The effects...
An oxine-impregnated emulsion was prepared by dissolving 100 mg of oxine and 0.3 ml of non-ionic surfactant (Span-80) in 10 ml of toluene and mixing with 3 ml of 1 mol l -1 hydrochloric acid by sonication (20 kHz). The water-in-oil emulsion was injected into 50 ml of water sample (containing iron(III) at the ppb level, pH 4-7) and dispersed by stirring for 10 min as numerous small globules...
The flow injection analysis systems have been developed for the simultaneous determination of iron(III) and copper(II) and of iron(III) and palladium(II) based on the photochemical reactions of their thiocyanato-complexes. In the first system, a sample solution was injected in to nitric acid solution and mixed with ammonium thiocyanate solution, followed by spectrophotometric monitoring of the thiocyanato-complexes...
A procedure for determination of concentrations of iron(III) and total iron by sequential injection analysis is described. The method is based on the strong blue-colored complexes formed between iron(III) and tiron. The absorbance of the complexes is measured spectrophotometrically at 635 nm. Oxidation of iron(II) and masking of interfering fluoride is simultaneously done by injecting one zone of...
Three flow injection (FI) systems were investigated for the determination of trace iron in beer: an FI-in-valve column-flame atomic absorption spectrophotometry (FI-FAAS) system, a spectrophotometric FI system with a column placed at the detection point, and an FI-spectrophotometric system with bead injection (FI-BI). Cationic exchange resin Dowex 50W X8 and iminodiacetate chelating resin, Chelex-100,...
The present work describes a novel method for the incorporation of Nile blue A into polyurethane foam matrix. This foam material was found to be very suitable for the extraction of metal ions from aqueous solutions. The characterization of Nile blue A grafted foam and the effect of halide concentration, pH, shaking time, extraction isotherm and capacity have been investigated. This foam material was...
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