Pre-concentration and separation of vanadium on Amberlite IRA-904 resin functionalized with porphyrin ligands

Among several methods, enrichment techniques based on sorption onto chelating resins seem convenient, rapid and capable to achieve a high concentration factor. Amberlite IRA-904 resin modified with tetrakis (p-carboxyphenyl) porphyrin (TCPP) was used to pre-concentrate vanadium species. Several parameters, such as sorption capacity of the chelating resin, pH for retention of V(IV) and V(V), volume of sample and eluent, were evaluated. Both vanadium species sorbed on TCPP-modified resin were eluted by use of 2 M nitric acid and determined by atomic absorption spectrometry. The recovery values were >94% and pre-concentration factor of 110 was obtained. For speciation studies, CDTA was added to the sample for complexing vanadium(IV), which was not retained on the microcolumn. The proposed method was examined for reference standard material (TM-25.2) and river water sample.     

Speciation analysis of vanadium in natural water samples by electrothermal vaporization inductively coupled plasma optical emission spectrometry after separation/preconcentration with thenoyltrifluoroacetone immobilized on microcrystalline naphthalene

A sensitive and simple method for low temperature electrothermal vaporization inductively coupled plasma optical emission spectrometry (ETV-ICP-OES) determination of V(IV) and V(V) after separation/preconcentration by a micro-column packed with immobilized thenoyltrifluoroacetone (TTA) on microcrystalline naphthalene has been developed. Thenoyltrifluoroacetone was used as both a chelating agent for micro-column separation/preconcentration and a chemical modifier for ETV-ICP-OES determination of vanadium. Both vanadium species could be trapped by micro-column at pH 4.0, and the vanadate (VO₂⁺) ion could be collected selectively at pH 2.4. Solid material loaded with analyte in the micro-column was dissolved with 100 μL of acetone containing 2.0 mmol L⁻¹ TTA and the vanadium was determined subsequently by ETV-ICP-OES. The concentration of vanadyl (VO²⁺) ion was calculated by subtracting the vanadate concentration from the total concentration of vanadium. Under the optimized experimental conditions, the detection limit (3σ) for the preconcentration of 5 mL of aqueous solution is 0.068 μg L⁻¹ for both species and the relative standard deviations were 4.3% for vanadium(V) and 4.8% for vanadium(IV) (c=10 μg L⁻¹, n=7), respectively. The method was applied successfully to the determination of vanadium(IV) and vanadium(V) in natural water samples.     

Speciation of vanadium (IV) and vanadium (V) with Eriochrome Cyanine R in natural waters by solid phase spectrophotometry

The separation and preconcentration of vanadium (IV) and vanadium (V) using Sephadex DEAE A-25 with Eriochrome Cyanine R has been studied, based on the preconcentration of vanadium (IV) in the first step and V(V) after reduction with ascorbic acid in the second step. Factors affecting the optimum fixation of the complex were investigated. The absorbance of the solid phase is measured directly at 563 nm for V(IV), at 585 nm for V(V) and at 750 nm for both. The proposed method provides a simple and specific procedure for the separation of vanadium in natural waters. The calibration graph is linear up to 150 ng/mL, with RSD of 4.7% for V(IV) and 4.0% for V(V). The detection limits are 1.6 and 1.4 ng/mL for V(IV) and V(V), respectively.     

Synthesis of chitosan resin possessing a phenylarsonic acid moiety for collection/concentration of uranium and its determination by ICP-AES

A chitosan resin possessing a phenylarsonic acid moiety (phenylarsonic acid type chitosan resin) was developed for the collection and concentration of trace uranium prior to inductively coupled plasma (ICP) atomic emission spectrometry (AES) measurement. The adsorption behavior of 52 elements was systematically examined by packing it in a minicolumn and measuring the elements in the effluent by ICP mass spectrometry. The resin could adsorb several cationic species by a chelating mechanism, and several oxo acids, such as Ti(IV), V(V), Mo(VI), and W(VI), by an anion-exchange mechanism and/or a chelating mechanism. Especially, U(VI) could be adsorbed almost 100% over a wide pH region from pH 4 to 8. Uranium adsorbed was easily eluted with 1 M nitric acid (10 mL), and the 25-fold preconcentration of uranium was achieved by using a proposed column procedure, which could be applied to the determination of trace uranium in seawater by ICP-AES. The limit of detection was 0.1 ng mL⁻¹ for measurement by ICP-AES coupled with 25-fold column preconcentration.     

Speciation of vanadium (IV) and vanadium (V) with Eriochrome Cyanine R in natural waters by solid phase spectrophotometry

The separation and preconcentration of vanadium (IV) and vanadium (V) using Sephadex DEAE A-25 with Eriochrome Cyanine R has been studied, based on the preconcentration of vanadium (IV) in the first step and V(V) after reduction with ascorbic acid in the second step. Factors affecting the optimum fixation of the complex were investigated. The absorbance of the solid phase is measured directly at 563 nm for V(IV), at 585 nm for V(V) and at 750 nm for both. The proposed method provides a simple and specific procedure for the separation of vanadium in natural waters. The calibration graph is linear up to 150 ng/mL, with RSD of 4.7% for V(IV) and 4.0% for V(V). The detection limits are 1.6 and 1.4 ng/mL for V(IV) and V(V), respectively. Received: 21 November 1996 / Revised: 15 April 1997 / Accepted: 18 April 1997     

Speciation and preconcentration of vanadium(V) and vanadium(IV) in water samples by flow injection-inductively coupled plasma optical emission spectrometry and ultrasonic nebulization

An on-line separation, preconcentration and determination system for vanadium(IV) and vanadium(V) comprising inductively coupled plasma optical emission spectrometry (ICP-OES) coupled to a flow injection (FI) method with an ultrasonic nebulization (USN) system was studied. The vanadium species were retained on an Amberlite XAD-7 resin as a vanadium-2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (V-5-Br-PADAP) complex at pH 3.7. Enhanced selectivity was obtained with the combined use of the formation on-line of the complexes and 1,2-cyclohexanediaminetetraacetic acid (CDTA) as masking agent. The vanadium complexes were removed from the microcolumn with 25% v/v nitric acid. A sensitivity enhancement factor of 225 was obtained with respect to ICP-OES using pneumatic nebulization (15-fold for USN and 15-fold for the microcolumn). The detection limit for the preconcentration of 10 mL of aqueous solution was 19 ng L-1. The precision for 10 replicate determinations at the 5 micrograms L-1 V level was 2.3% relative standard deviation (RSD), calculated from the peak heights obtained. The calibration graph using the separation and preconcentration system for vanadium species was linear with a correlation coefficient of 0.9992 at levels from near the detection limits up to at least 100 micrograms L-1. The method was successfully applied to the speciation of vanadium in river water samples.     

ICP-OES determination of traces of Ru, Au, V and Ti preconcentrated and separated by a new poly(epoxy-melamine) chelating resin from solutions

A new poly(epoxy-melamine) chelating resin is synthesized from epoxy resin and used for the preconcentration and separation of traces of Ru(III), Au(III), V(V) and Ti(IV) ions from sample solutions. The ions analyzed can be quantitatively enriched by the resin at a flow-rate of 2 mL/min at pH 4, and quantitatively desorbed with 10 mL of 1 mol/L HCl + 0.2 g CS(NH₂)₂ at a flow-rate of 1 mL/min with recoveries of over 97%. The chelating resin can be reused 7 times without obvious loss of efficiency. Thousand-fold excesses of coexistent ions caused little interference during the enrichment and determination steps. The RSDs for the determination of 50 ng/mL Ru(III) and Au(III), 5.0 ng/mL V(V) and Ti(IV) were in the range of 1.5–4.5%. The recoveries of added standards in a real sample solution are between 96% and 100%, and the results for the ions analyzed in a nickel alloy sample are in good agreement with their reported values.     

Multielement Preconcentration and Removal of Trace Metals by Solid-Phase Extraction

ABSTRACT

The solid phase extraction of trace amounts of some metal ions from their mixtures using cation exchanger Dowex 50Wx4, cellulose sorbent with phosphonic acid groups Cellex P, chelating resin Chelex 100 and SIO₂-TPP sorbent which contains porphyrin ligand covalently attached to aminopropyl silica gel was investigated. With respect to multielement preconcentration Cellex P and Chelex 100 seem to be the best sorbents; the recovery test for Al, Be, Cd, Ni, Pb and Zn were > 90%. Additionally, Cellex P appeared to be suitable for enrichment of Co and Mn. Silica-TPP sorbent could be applied as a selective collector for Mo(VI) and V(IV).     

Synthesis and efficiency of an epoxy-tannin chelating resin for preconcentrating and separating various rare elements

A new epoxy-tannin chelating resin was synthesized from epoxy resin and used for the preconcentration and separation of rare elements. The acidity, rate, reuse, capacity and interference on the adsorption of ions on the resin as well as the conditions of desorption of these ions from the resin were investigated by means of inductively coupled plasma atomic emission spectrometry (ICP-AES). The composition of the resin and mechanism of enrichment for some ions were discussed. The results show that the relative standard deviations for the determination of 50 ng ml⁻¹ Ga(III), In(III), Bi(III) and Sn(IV), 10 ng ml⁻¹ La(III), Y(III), Cr(III), Ti(IV) and V(V) and 1.0 ng ml⁻¹ Be(II) were in the range of 0.5–4.5%. The contents of these elements in a sample solution from a smelter determined by the new method were in agreement with those values obtained by Zeeman atomic absorption spectrometry with an average error <3.4%.     

Speciation of vanadium in water with quinine modified resin micro-column separation/preconcentration and their determination by fluorination assisted electrothermal vaporization (FETV)-inductively coupled plasma optical emission spectrometry (ICP-OES)

A simple and selective method of flow injection (FI) using a micro-column packed with quinine modified resin as solid phase extractant has been developed for preconcentration and separation of trace amount of vanadium(V) and vanadium(IV) in water samples, followed by determination with fluorination assisted electrothermal vaporization (FETV)-inductively coupled plasma optical emission spectrometry (ICP-OES). At pH 3 ∼ 3.8, the modified resin is selective towards V(V) and almost not towards V(IV), while, V(IV) could be quantitatively adsorbed by the modified resin at pH 5 ∼ 7. The two vanadium species adsorbed by modified resin could be readily desorbed quantitatively with 0.3 ml of 0.5 mol l⁻¹ HCl. Both vanadium species in elution were then determined by ETV-ICP-OES with the use of polytetrafluoroethylene (PTFE) as chemical modifier. Effects of acidity, sample flow rate, concentration of elution solution and interfering ions on the recovery of the analytes have been systematically investigated. Under the optimal conditions, the adsorption capacities of the quinine modified resin for V(V) and V(IV) are 7.6 and 8.0 mg g⁻¹, respectively. The detection limit (3σ) of V is 0.072 ng ml⁻¹ for FETV-ICP-OES and 0.56 pg ml⁻¹ for FETV-ICP-MS with enrichment factor of 62.5, and the relative standard deviation (R.S.D.) is 4.9% (n = 9, C = 0.2 μg ml⁻¹) and 3.8% (n = 9, C = 1.0 ng ml⁻¹), respectively. The proposed method has been applied to the determination of trace V(V) and V(IV) in different water samples, and the recoveries of V(V) and V(IV) are 100 ± 10%. In order to further verify the accuracy of the developed method, FETV-ICP-MS was employed to analyze the vanadium species in water samples after separation/preconcentration, and analytical results are in good agreement with that obtained by the proposed method. The developed method was also applied to the analysis of the total V in GBW07401 soil certified reference material and in GBW07605 tea leaves certified reference material, and the determined values coincided with the certified values very well.     

Speciation analysis of inorganic vanadium (V(IV)/V(V)) by graphite furnace atomic absorption spectrometry following ion-exchange separation

A sensitive and simple method of ion-exchange resin separation and graphite-furnace atomic absorption spectrometry (GFAAS) detection was proposed for the determination of inorganic vanadium species. Methylene Blue (MB) was used as a chelating agent of V(V) for ion-exchange separation. The complex of V(V) and MB could be trapped by ion-exchange resin at pH 3.0 and eluted by 1.0?mol?L^?1 NaOH. The vanadium species was determined subsequently by GFAAS. The concentration of V(IV) was calculated by subtracting the V(V) concentration from the total concentration of vanadium. Under the optimized experimental conditions, the detection limit of V(V) is 0.48?µg?L^?1 with RSD of 2.6% (n?=?5, c?=?2.0?µg?L^?1). In order to verify the accuracy of the method, a certified reference soil sample was analyzed, and the results obtained were in good agreement with the certified values. The range of recovery for V(IV) and V(V) was 97.8–99.3% and 101.7–103.6%, respectively. The proposed method was applied to the speciation analysis of vanadium in lake-water samples.     

ICP-OES determination of traces of Ru, Au, V and Ti preconcentrated and separated by a new poly(epoxy-melamine) chelating resin from solutions

A new poly(epoxy-melamine) chelating resin is synthesized from epoxy resin and used for the preconcentration and separation of traces of Ru(III), Au(III), V(V) and Ti(IV) ions from sample solutions. The ions analyzed can be quantitatively enriched by the resin at a flow-rate of 2 mL/min at pH 4, and quantitatively desorbed with 10 mL of 1 mol/L HCl + 0.2 g CS(NH₂)₂ at a flow-rate of 1 mL/min with recoveries of over 97%. The chelating resin can be reused 7 times without obvious loss of efficiency. Thousand-fold excesses of coexistent ions caused little interference during the enrichment and determination steps. The RSDs for the determination of 50 ng/mL Ru(III) and Au(III), 5.0 ng/mL V(V) and Ti(IV) were in the range of 1.5–4.5%. The recoveries of added standards in a real sample solution are between 96% and 100%, and the results for the ions analyzed in a nickel alloy sample are in good agreement with their reported values. Received: 12 May 1997 / Revised: 1 September 1997 / Accepted: 9 October 1997     

Determination of trace levels of dissolved vanadium in seawater by use of synthetic complexing agents and inductively coupled plasma-atomic emission spectroscopy (ICP-AES)

In the determination of traces of dissolved vanadium in complex matrices such as seawater, separation and enrichment from the matrix is of special importance. A wide variety of methods has been proposed for preconcentration, depending to the nature of samples and the methods to be used for measurement. Among these methods separation techniques based on sorption on to chelating resins seem convenient, rapid, and capable of achieving a high concentration factor. The methods proposed in this paper are based on the transformation of all dissolved vanadium species in seawater into organic complexes by use of synthetic complexing agents such as dithizone, luminol, or 8-hydroxyquinoline; the resulting vanadium-organic complexes were sorbed on to a C(18) column at a flow rate of 5 mL min(-1). The vanadium sorbed on the C(18) columns was then stripped by use of nitric acid (2 mol L(-1)) and analysed by inductively coupled plasma-atomic emission spectroscopy, ICP-AES. This method was optimised and use of other chelating resins, such as chelamine, chelex-100, and immobilised 8-hydroxyquinoline and was compared by passing seawater samples directly over the resins. The experimental conditions (pH, acid used for elution, and contact time between the liquid sample and the resin) were optimised. The results were compared for all the resins used and were indicative of excellent and coherent reproducibility.     

Determination of V(IV) and V(V) by electrothermal atomic absorption spectrometry following selective solid-phase extraction and the study on the change in the oxidation state of vanadium species in seawater during the sample storage.

The changes in the oxidation state of vanadium in artificial and natural seawater samples were studied by electrothermal atomic absorption spectrometry (ETAAS) with a direct injection of a resin suspension. V(IV) and V(V) were extracted as the complex with Chromazurol B and with N-cinnamoyl-N-2,3-xylylhydroxylamine, respectively, using a suspension of an anion-exchange resin and determined by ETAAS independently. The detection limits of both methods were 0.02 ng ml(-1) for 40 ml of a sample solution. The recovery tests for an artificial seawater sample spiked with V(IV) and/or V(V) were carried out carefully. The results showed that the recoveries of V(IV) or V(V) were 99.2-109% and the standard deviations were 1-6%. The total V was also determined after V(V) was reduced by ascorbic acid. In artificial seawater at pH 7.8, V(V) was stable but V(IV) was oxidized rapidly. In acidified artificial seawater (pH 2.0), V(IV) was oxidized slowly but only a small tendency of such reduction of V(V) was observed. In a natural seawater sample, V(IV) was not detected. The acidification of the natural seawater sample resulted in the reduction of V(V).     

Hollow-fibre liquid phase microextraction for separation and preconcentration of vanadium species in natural waters and their determination by electrothermal vaporization-ICP-OES

For separation and determination of vanadium(IV/V) species, a fast and sensitive method by combining hollow-fibre liquid phase microextraction (HF-LPME) with electrothermal vaporization (ETV)-ICP-OES has been developed. Two vanadium species (V(IV) and V(V)) were separated by HF-LPME with the use of ammonium pyrrolidinecarbodithioate (APDC) as chelating agent for complexing with different V species and carbon tetrachloride as the extraction solvent, and the vanadium in the post-extraction organic phase was injected into the graphite furnace for ETV-ICP-OES detection, in which APDC was acted as the chemical modifier. At pH 5.0, both V(IV)-APDC and V(V)-APDC were extracted quantitatively into CCl₄ for determination of total V. For speciation studies, 1,2-cyclohexanediaminetetraacetic acid (CDTA) was added to the sample for masking V(IV), so that only V(V)-APDC was extracted and determined. The concentration of V(IV) was calculated by subtracting the V(V) concentration from the total concentration of V. Under the optimized experimental conditions, the enrichment factor was 74 and the detection limits for V(IV) and V(V) were 86 pg mL⁻¹ and 71 pg mL⁻¹, respectively. The proposed method has been applied to the speciation of V in environmental water samples, and the recovery was in the range of 94%-107%. The results show that V(V) is the dominant existence form in oxygenic water and V(IV) could not been detected. In order to validate the developed procedure, a NIES No.8 vehicle exhaust particulates certified reference material was analyzed, and the results obtained for total vanadium are in good agreement with the certified values. The proposed method is simple, rapid, selective, and sensitive and no oxidation/reduction is required, it is applicable to the speciation of vanadium in environmental samples with the complicated matrix.     

Synthesis and efficiency of a spherical macroporous epoxy-polyamide chelating resin for preconcentrating and separating trace noble metal ions

The determination of noble metals in various materials usually requires their preconcentration and separation from other elements. In spite of the improvements in analytical instrumentation and the development of new analytical techniques such as ICP-MS, which are capable of detecting metal ions at ppt levels, the interference caused by the sample matrix still exists and is perhaps the most serious problem, making a pre-determination enrichment step necessary. Thus, the search for efficient preconcentration and separation methods is essential. A series of chelating resins that can selectively adsorb noble metal ions from aqueous solutions have been described. Functional groups, such as salicylaldoxime and thiosemicarbazide have been incorporated in cross-linked polymers or porous silica gel. These resins have very high selectivity for one or several types of noble metal ion. However, desorption of noble metals from these resins is usually difficult. Hence, the development of an adsorbent from which noble metals can be easily desorbed is needed. In this paper, a new spherical macroporous epoxy-polyamide chelating resin that met this requirement was synthesized by one step reaction. The synthesis of the resin was safe, rapid and more simple and economical than many report adsorbents. Meanwhile, the resin showed more advantages: better acid and alkali resistance; higher adsorption capacity and lower preconcentration concentrations. A resin column procedure combined with inductively coupled plasma atomic emission spectrometry (ICP-AES) for the determination of trace Rh(III), Ru(III) and Ir(IV) in real samples was established.     

Synthesis of spherical macroporous epoxy-dicyandiamide chelating resin and properties of concentration and separation of trace metal ions from samples

A novel spherical macroporous epoxy-dicyandiamide chelating resin is synthesized simply and rapidly from epoxy resin and use for the preconcentration and separation of trace Ga(III), In(III), Bi(III), Sn(IV), Pb(II), V(V) and Ti(IV) ions from solution samples. The analyzed ions can be quantitatively concentrated by the resin at flow rate of 3.0 ml min(-1) at pH 3, and can also be desorbed with 10 ml of 4 M HCl+0.2 g thiourea from the resin column with recoveries of 97-100%. The chelating resin is reused for eight times, the recoveries of these ions are still over 92%, and a 100-1000 times of excess of Fe(III), Al(III),Ca(II), Mg(III), Ni(II), Mn(II), Co(II), Cu(II), Zn(II), and Cd(II) cause no interference in the determination of these ions by inductively-coupled plasma atomic emission spectrometry. The capacities of the resin for the analytes are in the range of 0.66-4.20 mmol g(-1). The results show the relative standard deviation for the determination of 50.0 ng ml(-1) Ga(III), In(III), Bi(III), Sn(IV) and Pb(II), 5.0 ng ml(-1) V(V) and Ti(IV) are in the range of 1.2-4.0%. The recoveries of a standard added in real solution samples are between 96 and 100%, and the concentration of each ion in mineral sample detected by the method is in good agreement with the certified value.     

Synthesis and Efficiency of an Epoxy-Urea Chelating Resin for Preconcentrating and Separating Trace Bi,In, Sn,Zr, V And Ti From Solution Samples

Abstract

A new epoxy-urea chelating resin was synthesized from epoxy resin and used for the preconcentration and separation of trace Bi(III), In(III), Sn(IV), Zr(IV), V(V) and Ti(IV) ions from solution samples. The analyzed ions can be enriched at pH 5 at a flow rate of 1–4 ml/min, and can be also desorbed with 10 mL of 2 M HCl +0.1g NH₄F solution from the resin column, with recoveries over 97%. The chelating resin reused 6 times can still adsorb quantitatively the Bi, In, Sn, Zr, V and Ti ions, and eighty to thousand-fold excesses of Ca(II), Mg(II), Cu(II), Zn(II), Al(III), Sb(III), Ni(II), Mn(II) and Fe(III) cause little interference with the enrichment and determination of these ions. The RSDs of the proposed method for the determination of 500–50 ng/ml Bi, In and Sn, 50–5.0 ng/ml Zr, V and Ti were in the range of 0.4 ～ 4.0%, the enrichment factor of the resin for the ions is in the range of 10–100. The recoveries of added standard in waste water are between 96% and 100%, and the concentration of each ion in alloy steel sample determined by the method is in good agreement with the reference value analyzed by a steel plant with average error <2.8%.     

Selective extraction of Th(IV) over U(VI) and other co-existing ions using eosin B-impregnated Amberlite IRA-410 resin beads

A new chelating polymeric sorbent as an extractant impregnated resin (EIR) has been developed using eosin B and Amberlite IRA-410 resin. The impregnation process was characterized by FT-IR spectroscopy. The eosin B-impregnated resin showed superior binding affinity for Th(IV) over U(VI) and many co-existing ions. The influence of various physicochemical parameters on the recovery of Th(IV) were optimized by both static and dynamic methods. The Langmuir adsorption isotherm gave a satisfactory fit of the equilibrium data. The kinetic studies performed for Th(IV) sorption revealed that <20 min was sufficient for reaching equilibrium metal ion sorption. A preconcentration factor of 100 was found for the column-mode extraction. The accuracy of the developed method in conjunction with Arsenazo III procedure was tested by analyzing geological reference materials and seawater sample, which are prepared, synthetically. Furthermore, the above procedure has been successfully employed for the analysis of natural water samples.     

Synthesis of cross-linked chitosan modified with the glycine moiety for the collection/concentration of bismuth in aquatic samples for ICP-MS determination.

A chelating resin, cross-linked chitosan modified with the glycine moiety (glycine-type chitosan resin), was developed for the collection and concentration of bismuth in aquatic samples for ICP-MS measurements. The adsorption behavior of bismuth and 55 elements on glycine-type chitosan resin was systematically examined by passing a sample solution containing 56 elements through a mini-column packed with the resin (wet volume; 1 ml). After eluting the elements adsorbed on the resin with nitric acid, the eluates were measured by ICP-MS. The glycine-type chitosan resin could adsorb several cations by a chelating mechanism and several oxoanions by an anion-exchange mechanism. Especially, the resin could adsorb almost 100% Bi(III) over a wide pH region from pH 2 to 6. Bismuth could be strongly adsorbed at pH 3, and eluted quantitatively with 10 ml of 3 M nitric acid. A column pretreatment method with the glycine-type chitosan resin was used prior to removal of high concentrations of matrices in a seawater sample and the preconcentration of trace bismuth in river water samples for ICP-MS measurements. The column pretreatment method was also applied to the determination of bismuth in real samples by ICP-MS. The LOD of bismuth was 0.1 pg ml(-1) by 10-fold column preconcentration for ICP-MS measurements. The analytical results for bismuth in sea and river water samples by ICP-MS were 22.9 +/- 0.5 pg ml(-1) (RSD, 2.2%) and 2.08 +/- 0.05 pg ml(-1) (RSD, 2.4%), respectively.