Spectrophotometric determination of traces of cobalt in water after preconcentration on reagent-loaded polyurethane foams

Open-cell Polyurethane foam loaded with 1-(2-pyridylazo)-2-naphthol (PAN) is used for the preconcentration of traces of cobalt from water at the ppb level with a preconcentration tration factor of 1000 or more. Cobalt is retained quantitatively from thiocyanate solution on the loaded foam placed in a column, at flow rates up to 100 ml min^-1, and then recovered completely from the foam by elution with acetone. Cobalt is determined spectrophotometrically with 4-(2-pyridylazo)-resorcinol at 510 nm, after the removal of interfering ions with a Dowex 1-X8 column. The amount of PAN leached by the water percolating through the column is too low to affect quantitative retention of traces of cobalt.     

Studies in the complex formation of metal ions with sugars. I. The complex formation of cobalt(II), cobalt(3), copper(II) and nickel(II) with mannitol

The use of elastic polyurethane foam as a support for chloranil was proved successful. Reductions of cerium(IV), vanadium(V) and iron(II) on foam-filled columns were carried out quantitatively and rapidly. The effect of flow-rate and temperature on the reduction of each metal ion was examined in detail. Cerium(IV) was reduced quantitatively on passing through the foam-redox column at flow-rates of 2–11 ml min^-1 at room temperature. The reduction of vanadium(V) and iron(III) was slower; complete reduction occurred only at flow-rates up to 4 and 2 ml min^-1 for V(V) and Fe(III), respectively. At 35°, however, it was possible to use flow-rates of 7 and 6 ml min^-1 for the quantitative reduction of V(V) and Fe(III), respectively.     

Preconcentration of phenlymercury,methylmercury and inorganic mercury from natural waters with diethylammonium diethyldithiocarbamate-loaded polyurethane foam

The percentage extraction of organomercurials and inorganic mercury on polyurethane foam loaded with diethylammonium diethyldithiocarbamate is high over a wide pH range, particularly when a plasticizer is added to the foam. Flow rates up to 120 ml min^-1 give quantitative extraction of inorganic mercury. Mercury(II), methylmercury and phenylmercury ions at 1 μg l^-1 levels can be almost quantitatively preconcentrated from tap and saline water, and eluted from the foam with acetone.     

Preconcentration of antimony(III) from water with thionalide loaded on glass beads with the aid of collodion

2-Mercapto-N-2-naphthylacetamide (thionalide) loaded on glass beads with the aid of collodion is used for preconcentration of microgram levels of antimony(III) from aqueous solution. Antimony is quantitatively retained on the loaded beads from 0.4–0.8 mol l^?1 hydrochloric acid solutions; equilibration is achieved within 1 min. The retention capacity of the beads is 0.2 μml Sb g^?1 at 0.6 mol l^?1 hydrochloric acid. The maximum flow rate for quantitative retention is 1.27 ml min^?1 cm^?2. Antimony retained on the column is completely eluted with 10 ml of 6.0 mol l^?1 hydrochloric acid at flow rates<1.9 ml min^?1 cm^?2.     

Untersuchungen zur adsorptiven Anreicherung von Elementspuren an Adsorberharzen

Summary The use of a short column filled with 0.5 g Amberlite XAD resin is characterized for the trace preconcentration from aqueous solutions. For this a suitable algorithm describing the breakthrough curves of columns with a low number of theoretical plates is applied. The influence of the flow rate on the maximal sampling volume is examined. For the sorption of 1,10-phenanthroline the number of theoretical plates of the column with flow rates between 6–80 ml · min^–1 was determined to be 1–20. The results indicate that flow rates of 10–40 ml · min^–1 are generally suitable for quantitative trace preconcentration.

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Teil III: Fresenius Z Anal Chem (1989) 334:514–520     

Preconcentration of trace manganese from natural waters by complexation with dithiocarbamate and adsorption onto C18-solid phase extraction column for neutron activation analysis

A method was developed for the preconcentration and separation of trace manganese from natural water samples by complexation with dithiocarbamate followed by adsorption onto C₁₈-solid phase extraction column prior to irradiation. The Mn recovery was better than 99.8% without inteference from iron(III) at 5 mg^.l^-1, copper(II), zinc(II), aluminum(III) and cobalt(II) at 0.5 mg^.l^-1 and sodium(I), potassium(I), magnesium(II) and calcium(II) at 1 mg^.l^-1. The separation factor was 100 and the detection limit was 0.01 μg^.l^-1 with good precision and accuracy with a relative error lower than 3%. The method was applied to the determination of Mn in tap, well, river and treated water samples. This revised version was published online in August 2006 with corrections to the Cover Date.     

Flame atomic absorption determination of manganese(II) in natural water after cloud point extraction

The possibility to use 4-(2-pyridylazo)resorcinol (PAR) and 1-(2-pyridylazo)-2-naphthol (PAN) for manganese(II) concentrating by the micellar extraction at cloud point (CP) temperature and subsequent atomic absorption spectrometry (AAS) determination was investigated. Under the optimum conditions, preconcentration of 100 ml of water sample in the presence of 1% non-ionic surfactant (NS) OP-7, 1×10⁻⁴ M 1-(2-pyridylazo)-2-naphthol permitted the detection 5 μg l⁻¹ manganese. The proposed method has been applied to the AAS determination of manganese in water samples after cloud point extraction.     

Continuous-flow system for the determination of cobalt in sea and river water: In-Line Preconcentration/Separation Coupled with Catalytic Determination

Cobalt is preconcentrated on a column packed with silica-immobilized 8-quinolinol and separated in a second column packed with a strongly acidic cation-exchange resin. The catalytic action of cobalt ions on the hydrogen peroxide oxidation of protocatechuic acid is used in the determination. The limit of detection is 5 × 10^?3 ng ml^?1. The separation step prevents interference from species such as iron(III) and manganese(II). The recommended procedure is applied to the coastal sea water and surface river water.     

Separation and determination of traces of heavy metals complexed with humic substances in river waters by sorption on indium-treated amberlite xad-2 resin

A nonionic macroreticular styrene/divnylbenzene copolymer, Amberlite XAD-2 resin is pulverized to 1–10 μm and treated with indium ions to saturate traced of cation exchange sites for the quantitative separation of humic complexes from cations. A 100-ml filtered sample is passed through an indium-treated XAD-2 column (16 diameter, 5 mm tall) at pH 5 at a flow rate of 2 ml min^? to sorb heavy metals complexed with humic and fulvic acids. Inorganic cations and anions, EDTA complexes and colloidal hydrated iron(III) oxide are not retained on the column at all. The heavy metals sorbed on the column are then ultrasonically desorbed with 0.5 M nitric acid and determined by graphite-furnace atomic absorption spectrometry. The results fo two river water samples obtained are in good agreement with those obtained when the macroreticular weak-base anion-exchanger DEAE-Sephadex A-25 is used.     

Synthesis and properties of new chelating resin with a spacer containing alpha-nitroso-beta-naphthol as the functional group

A new chelating ion-exchange resin with a spacer CH₂-NH-C₆H₄- based on a microreticular chloromethylated styrene-divinylbenzene copolymer containing α-nitroso-β-naphthol as a functional group has been synthesized. The sorption characteristics for manganese(II), iron(III), cobalt(II), nickel(II), copper(II), and zinc(II) have been investigated over the pH range 1.0–7.0. The resin is highly stable in acidic and alkaline medium. Iron(III) and cobalt(II); copper(II) and iron(III) are separated very effectively in a column operation by stepwise elution.     

A cellulose-based carboxyl cotton chelator having citric acid as an anchored ligand: preparation and application as solid phase extractant for copper determination by flame atomic absorption spectrometry

Citric acid was thermochemically esterified onto defatted cotton fibre to produce a carboxyl cotton chelator (CCC), which had been used for extraction of copper prior to its determination by flame atomic absorption spectrometry. The extraction of copper has been studied under both batch and column methods. Quantitative extraction of copper was achieved in the pH range 4–7. The time needed to extract each sample was less than 30 min by the batch method. The copper extraction capacity of CCC was found to be 22.7 mg g⁻¹ at optimal pH value. The elution was quantitative with 1 mol L⁻¹ hydrochloric acid. The feasible flow rate of copper-containing solution for quantitative extraction onto the column packed with CCC was 0.5–4.0 mL min⁻¹, whereas for elution it was less than 1.5 mL min⁻¹. A 100-fold extraction factor could be achieved under the optimal column conditions. The tolerance limits for common metal ions on the extraction of copper and the time of column reuse were investigated. The proposed method has been successfully applied for extraction and determination of copper in industrial wastewater and natural water samples.     

Flow-injection determination of europium after on-line reduction

A zinc reductor minicolumn is used in a flow-injection system for reduction of europium(III) to europium(II). Europium(II) is indirectly determined either spectrophotometrically by oxidation with iron(III) and reaction of the iron(II) formed with 1,10- phenanthroline, or spectrofluorimetrically by reaction with cerium(IV) and measurement of the cerium(III) produced. The reductor functions efficiently at flow rates up to 1 ml min^?1, which allows sample injection rates up to 100 h^?1. Linear calibration is achieved for 10–200 and 0.5–4 μg ml^?1 with detection limits of 2.5 and 0.25 μg ml^?1, by spectrophotometry and spectrofluorimetry, respectively.     

Spectrophotometric Determination of Diphenadione Via its Metal Complexes

Abstract

Spectrophotometric procedure is described for the quantitative determination of diphenadione [2-(diphenylacetyl)-1,3-indandione], based on direct spectrophotometric measurements of the absorbances of its iron (III), iron (II) and cobalt (II), metal complexes at 488 nm, 505 nm and (334 nm, 372 nm), respectively. The drug reacts with metals in the ratio of 3:1 and 2:1 for iron (III) and for both iron (II) and cobalt (II) respectively. The obtained complexes have apparent molar absorptivities of 1.48 × 10³ 1 mol^?1 cm^?1, 0.714 × 10³ 1 mol^?1cm^?1 and (1.70 × 10³ 1 mol^?1cm^?1, 1.93 × 10³ 1 mol^?1cm^?1) for iron (III), iron (II) and cobalt (II) complexes, respectively. The procedure is suggested for the determination of 51–400 μg.ml^?1 diphenadione via the iron (II) complex and 35–170 μg.ml^?1 diphenadione via both cobalt (II) and iron (III) complexes. The suggested procedure has accuracies of 99.79 ± 0.67%, 99.64 ± 0.37% and (100.09 ± 0.53%, 99.99 ± 0.42%) for the metal complexes of iron (III), iron (II) and cobalt (II), respectively.     

Non-isothermal dehydration and decomposition of <Emphasis Type="Italic">dl</Emphasis>-lactates of transition metals and alkaline earth metals

A comparative study of the non-isothermal decomposition of the dl-lactate hydrates of magnesium, calcium and strontium has been made with that of the dl-lactate hydrates chromium(III), manganese(II), iron(II), cobalt(II), nickel(II), copper(II) and zinc(II) keeping dry air as the purge gas and the heating rate maintained at 10 K min^-1. While the dl-lactates of manganese(II), cobalt(II) and copper(II) followed single step decomposition scheme suggesting that dehydration and decomposition steps overlapped, the dehydration steps of the other compounds were distinct. &agr;-T plots of none of the dehydration steps showed any induction period, indicating no physical desorption, nucleation or branching. Neither the &agr; _max-values nor the onset temperatures of the dehydration steps did show any pattern. The TG data of the dehydration steps have also been analyzed using the Freeman-Carroll, Horowitz-Metzger, Coats-Redfern, Zsak&oacute;, Fuoss-Salyer-Wilson and Karkhanavala-Dharwadkar methods. Values of order of reaction, activation energy and Arrhenius factor have been approximated and compared. There are similarities in the activation energy values for the dehydration steps (&lt; 60 kJ mol^-1 in general). It is higher with group 2 metals and lower in transition metals (maximum in magnesium and lowest in chromium and iron lactates). In cases of overlapping of dehydration and decomposition steps, the activation energy values are on the lower side with the same trend (lower in cobalt and copper cases).     

Determination of transition metal ions in tobacco as their 2-(2-quinolinylazo)-5-dimethylaminophenol derivatives using reversed-phase liquid chromatography with UV-VIS detection

This paper reports the utilization of solid-phase extraction and the reversed-phase high-performance liquid chromatography for the determination of six important transition metal ions: iron, cobalt, nickel, copper, zinc and manganese in tobacco with 2-(2-quinolinylazo)-5-dimethylaminophenol (QADMAP) as chelating reagent. Iron, cobalt, nickel, copper, zinc and manganese ions react with QADMAP to form colored chelates in the medium of acetic acid-sodium acetate buffer solution (pH 4.0). These chelates can be enriched by solid-phase extraction with Waters Sep-Pak-C18 cartridge, and eluted the retained chelates from cartridge with tetrahydrofuran. The chelates were separated on a Waters Nova-Pak-C18 column (150x3.9 mm, 5 microm) by gradient elution with methanol (containing 0.5% of acetic acid) and 0.05 mol/l pH 4.0 acetic acid-sodium acetate buffer solution as mobile phase at a flow-rate of 0.5 ml/min. The detection limits of iron, cobalt, nickel, copper, zinc and manganese are 10, 12, 8, 13, 17 and 22 ng/l, respectively. This method had been applied to the determination of iron, cobalt, nickel, copper, zinc and manganese in tobacco with good results.     

Microbore columns in quantitative column liquid chromatography

Summary Some quantitative implications of the use of microbore columns in column liquid chromatography are investigated. Although for several pumps the flow rate stability at 50 l min^–1 is slightly worse than that of pumps operating at 1 ml min^–1, the quantitative performance with respect to repeatability and reproducibility of response factors equals that of conventional liquid chromatography. Thermostatting is strongly recommended for microbore column operation.     

Preconcentration of silver(I), gold(III) and palladium(II) in sea water with p-dimethylaminobenzylidenerhodanine supported on silica gel

A water-insoluble chelating material, p-dimethylaminobenzylidenerhodanine on silica gel (DMABR—SG) is described for preconcentration of trace amounts of silver(I), gold(III) and palladium(II) from water samples. Radioactive tracers (^110mAg and ¹⁹⁵Au) were used to study the behavior of silver and gold; palladium was monitored spectrophotometrically as its 1-(2-pyridylazo)naphthol complex in chloroform. In batch experiments, silver was quantitatively retained on the DMABR—SG at acidities ranging from 1.7 M to pH 5, and gold from 3 M to pH 5; equilibrium was achieved within 1 min for both elements. From sea water, silver ion was completely retained at pH 1.0–6.5 and gold ion at pH 1.0–3.5. In the case of palladium, shaking for about 20 min was required for quantitative retention at pH 1.0–5.0 for aqueous solution and at pH 1.0–7.0 for sea water. The chelating capacity of the DMABR—SG was 23 μmol Ag, 11 μmol Au and 11 μmol Pd per g. Quantitative recovery of silver and gold on DMABR—SG columns from sea water was achieved at higher flow rates (1–2 l h^-1 and 2–3 l h^-1, respectively) than with other chelating resins, e.g., Chelex 100, palladium required slower flow rate (150 ml h^-1). Silver retained on the DMABR—SG column was completely eluted with 20 ml of 2.5% sodium thiosulfate solution but palladium remained on the column. Silver, gold and palladium were quantitatively eluted with 20 ml of 0.1% thiourea in 0.1 M hydrochloric acid.     

Reversed phase foam chromatography : Separation of iron from copper,cobalt and nickel in the tri-n-butyl phosphate-hydrochloric acid system

The separation of iron from cobalt, copper and nickel by reversed-phase foam chromatography was investigated. The distribution of Fe, Co and Cu in TBP-HCl and TBP(polyurethane foam)-HCl systems was measured. Iron can be separated from the three other metals on polyether-type polyurethane foam columns loaded with TBP. The break-through curve of iron on TBP (polyurethane foam) columns was measured. The column was found suitable for the separation of ⁵⁸Co and ⁵⁹Fe isotopes.     

Determination of manganese by flame atomic absorption spectrometry after its adsorption onto naphthalene modified with 1-(2-pyridylazo)-2-naphthol (PAN)

A system for determination of manganese, after preconcentration with 3% (w/w) 1-(2-pyridylazo)-2-naphthol (PAN), adsorbed on microcrystalline naphthalene is proposed. An amount of 200 mg of this complexing mixture is placed in a glass column and conditioned with a NH₄Cl/NH₄OH buffer solution (pH 9.5). The aqueous sample, containing manganese, is treated with an ammonium tartrate solution, then with a hydroxylammonium chloride solution and, finally, with a buffer solution. The resulting solution is passed through the column containing microcrystalline naphthalene modified with 1-(2-pyridylazo)-2-naphthol (PAN) where Mn(II) is retained. The column is first washed with deionized water and then with 10.0 ml of dimethylformamide to dissolve the Mn(II)-PAN/naphthalene complex. Manganese is determined by air-acetylene flame atomic absorption spectrometry. About 1 μg of manganese can be concentrated from 200 ml of aqueous sample, allowing a preconcentration factor of 20, a limit of quantification of 5 ng ml⁻¹ and R.S.D. of 3.8%. The accuracy was ascertained using certified reference materials, including samples of urine and glass. Water samples were also analysed and the results are in good agreement with those obtained by graphite furnace atomic absorption spectrometry.     

High performance liquid chromatographic separation and UV determination of cobalt, copper iron and platinum in pharmaceutical preparations using bis(isovalerylacetone)ethylenediimine as complexing reagent

The reagent bis(isovalerylacetone)ethylenediimine(H₂IVA₂en) has been examined for HPLC separation and UV determination of cobalt, copper, iron and platinum using off-line precolumn derivatization and extraction in chloroform. The complexes of cobalt(II), cobalt(III), iron(II), iron(III) and the reagent have been subsequently separated on a Microsorb C-18 column. The complexes were eluted isocratically using ternary mixtures of methanol/water/acetonitrile. Detection was achieved by UV monitoring. Detection limits for Co(II), Co(III), Fe(II) and Fe(III) were 2.5–5.0 ng/injection, based on 0.5–1.0 g/ml with 5 l/injection. The concentration of cobalt(II) and cobalt(III) in aqueous solution have been determined. The presence of oxovanadium(IV), platinum(II), and nickel(II) did not affect the determinations. The HPLC method developed has been applied to the determination of cobalt, copper, iron and platinum in pharmaceutical preparations at the 30 g/g to 15 mg/g level and the obtained results were compared to those of atomic absorption spectrometry.