Trace Amounts Of Cu Research Articles

Trace Metal Enrichment Using Gold Nanoparticle Loaded on Activated Carbon Modified with 1-((6-(-(2,4-dihydroxybenzylideneamino))hexylimino) Methyl)benzene-2, 4-diol

In this study, a new sorbent based on the modification of gold nanoparticle loaded on activated carbon (Au-NP-AC) with 1-((6-(-(2,4-dihydroxybenzylideneamino))hexylimino) methyl)benzene-2, 4-diol (DHBAHMB) was synthesis and its efficient application for trace metal enrichment was examined. The proposed sorbent (Au-NP-AC-DHBAHMB) has been applied for enrichment and preconcentration of trace amount of Cu 2+ , Fe 3+ and Zn 2+ ions in real samples. The metal ions retained on proposed sorbent via chelation with the DHBAHMB efficiency was eluted by HNO3 and detected by FAAS. The effect of analytical parameters including pH, amount of ligand and solid phase and the conditions (type, concentration and volume of eluent) of the eluent were optimized. Following optimization of variables, preconcentration factors of 165, 170 and 180 for Cu 2+ , Fe 3+ and Zn 2+ metal ions, respectively, with detection limits of 1.4-2.6 ng mL -1 . The method has been applied for the extraction and determination of the ion content in same real sample with recoveries in range of 95-99.6 % and a relative standard deviation of (RSD lower than 4.0 %).

Solid-Phase Extraction of Some Heavy Metal Ions on a Double-Walled Carbon Nanotube Disk and Determination by Flame Atomic Absorption Spectrometry

A new preconcentration method was developed for the determination of trace amounts of Cu(II), Fe(III), Pb(II), Ni(II), and Cd(II) on a double-walled carbon nanotube disk. 4-(2-Thiazolylazo) resorcinol was used as a complexing reagent. The effects of parameters, including pH of the solutions, amounts of complexing reagent, eluent type, sample volume, flow rates of solutions, and matrix ions were examined for quantitative recoveries of the studied analyte ions. The retained metal ions were eluted by 2 M HNO3. The LOD values for the analytes were in the range of 0.7-4.4 microg/mL. Natural water samples and standard reference materials were analyzed by the presented method.

Synthesis and application of chloromethylated polystyrene modified with 1-phenyl-1,2-propanedione-2-oxime thiosemicarbazone (PPDOT) as a new sorbent for the on-line preconcentration and determination of copper in water, soil, and food samples by FAAS

In this paper, we report a simple and sensitive on-line solid phase extraction system for the preconcentration and determination of Cu(II) by flame atomic absorption spectrometry (FAAS). This method is based upon the on-line retention of copper at pH 5.0 on a minicolumn packed with chloromethylated polystyrene modified by 1-phenyl-1,2-propanedione-2-oxime thiosemicarbazone (PPDOT) as a new solid-phase extraction (SPE) sorbent. The retained Cu(II) ions were eluted with 1.0 M HNO 3, and transported directly to FAAS for determination. Several chemical and flow variables were studied and optimized for a quantitative preconcentration and determination of copper(II). At the optimized conditions, for preconcentration of 10.0 mL of a sample solution, a linear calibration graph was obtained over the concentration range of 3.00–120.0 μg L −1 for Cu(II). The limit of detection (3 σ), limit of quantification (10 σ), and enrichment factor are 0.56 μg L −1, 2.0 μg L −1 and 41, respectively. The relative standard deviation ( n = 6) at 20 μg L −1 of Cu(II) is 2.0%. This method could be applied for determination of trace amounts of Cu(II) in water, soil, and food samples with satisfactory results.

Determination of Cu, Fe, and Ni in Spices after Preconcentration on Diaion‐HP 20 Resin as Their Zincon Complexes

AbstractIn this work, a new separation–preconcentration method was developed for the determination of trace amounts of Cu(II), Ni(II), and Fe(III) by flame atomic absorption spectrometry (FAAS). Analytes were complexed by using zincon (2‐[2‐[alpha(2‐hydroxy‐5‐sulfophenylazo) benzylidene] hydrazino] benzoic acid sodium salt). The analyte ions were quantitatively adsorbed on a Diaion HP‐20 resin at pH 5. The retained metal ions on the resin were eluted by acetone. The analytical parameters such as pH of the sample, eluent type and volume, sample volume, and flow rates of the solution and the eluent were investigated. The influences of concomitant ions on the recoveries of the analytes were also examined. The instrumental detection limits for the analytes after application of the presented solid‐phase extraction procedure were in the range of 0.72–1.41 µg/L. The validation of the presented procedure was checked by analyzing certified reference material of SRM1515 Apple Leaves. The procedure was performed by analyzing some spice samples.

Silica-modified magnetic nanoparticles functionalized with cetylpyridinium bromide for the preconcentration of metals after complexation with 8-hydroxyquinoline

Magnetically driven separation technology has received considerable attention in recent decade for its great potential application. In this study, we investigate the application of silica-modified magnetite nanoparticles (NPs) coated with a cationic surfactant as adsorbent for microextraction and determination of trace amounts of Cu(II), Ni(II), Co(II), Cd(II), Pb(II) and Mn(II) from environmental water samples. The synthesized silica-coated NPs in combination with cetylpyridinium bromide have the ability to adsolubilize the metal ions after complexation with 8-hydroxyquinoline. The NPs bearing the target metals are easily separated from the aqueous solution by applying an external magnetic field and the complexed metals were desorbed using acidic methanol. The desorbed analytes are introduced into the graphite furnace of an atomic absorption spectrometer. The effect of pH, complexing agent, amount of cetylpyridinium bromide, microextraction time, desorption conditions, ionic strength on extraction efficiency of the metal ions are investigated and optimized. Under the optimized conditions, the detection limits for Cu(II), Ni(II), Co(II), Cd(II), Pb(II) and Mn(II) are 4.7, 9.1, 9.5, 2.3, 7.4 and 15.3 ng L −1, respectively and the relative standard deviations ( n = 6) are less than 3.6%. The accuracy of the method was evaluated by recovery measurements on the spiked samples and good recoveries (93–113%) with low RSDs were achieved.

Development of a new enrichment method for simultaneous determination of copper and zinc in water samples

In the present study, an enrichment and separation method for the simultaneous determination of trace amounts of Cu and Zn in water samples was developed. Copper and Zn ions found in water matrix in trace amounts were preconcentrated on Duolite XAD 761 resin without using any chelating agent and determined by flame atomic absorption spectrometer (FAAS). Experimental parameters such as pH, concentration of metal ions, amount of resin, and sample volume for quantitative determination of Cu and Zn ions were optimized. The elution process was performed by using 5 ml of 2 mol/L HCl solution. The preconcentration factors for Cu and Zn were found to be 160 and 200, respectively. Under optimized conditions, limit of detection for Cu and Zn were 2.46 and 3.54 µg/L, respectively. The Langmuir adsorption model was applied to describe the equilibrium isotherm. The Langmuir monolayer adsorption capacity of resin was estimated as 31.2 and 17.7 mg/g for Cu and Zn, respectively. The proposed method was successfully applied to determine the Cu and Zn content of various water samples.

Alumina coated with oxazolone derivative for extraction of trace amounts of cadmium and copper from water and plant samples

A solid phase extraction procedure is proposed for simultaneous separation and preconcentration trace amounts of Cu(II) and Cd(II) using alumina coated with N′-{4-[4-{1-[4-(dimethylamino)phenyl]methylidene}-5-(4-H)oxazolone]phenyle}acetamide and determination by flame atomic absorption spectrometry. Using 0.1 g of the sorbent, the metal ions were sorbed at pH 7 and recovered with 5.0 mL of 0.5 mol L −1 HNO 3. It was found that extraction can be performed from the sample volumes of 2000 and 800 mL for Cu and Cd, respectively (preconcentration factors of 400 for Cu and 160 for Cd). Obtained sorption capacities for 1 g sorbent were 8 mg Cu and 14 mg Cd. The linearity was maintained in the concentration range of 0.1 ng mL −1 to 7.0 μg mL −1 for Cu and 0.13 ng mL −1 to 2.0 μg mL −1 for Cd in the original solution. Eight replicate determinations of a mixture containing 1.0 μg mL −1 each of the elements in the final solution gave relative standard deviation ±1.6 and ±1.3% for Cu and Cd, respectively. The detection limit was calculated as 0.06 and 0.05 ng mL −1 for Cu and Cd, respectively. The proposed method was successfully applied to the determination trace amounts of Cu and Cd in the water and plant samples.

Adsorption of gold(III) from waste rinse water of semiconductor manufacturing industries using Amberlite XAD-7HP resin

Advanced hydrometallurgical separation processes are gaining significant importance for the recovery of gold from the aqueous solutions viz. leach liquor of waste electronics, plating material solutions, and waste wash water from electronic industries. In the present investigation, gold adsorption from the waste rinse water of semiconductor manufacturing industries is reported using Amberlite XAD-7HP. For experimental purposes, chloride waste rinse water that contained primarily Au (281 mg/ L) with trace amounts of Cu, Ni, Zn, Sn etc was used. Batch studies were carried out to optimize various process parameters, including contact time, acidity of solution, and resin dosage for the adsorption of gold from the above waste effluent. Adsorption of 92.25% gold was found from the waste solution within a contact time of 30 minutes at an aqueous to resin (A/R) ratio of 25 mL/g and an equilibrium pH of 0.63. In optimal conditions, the loading capacity of resin for gold was observed to be 58.82 mg of gold/g of resin. The gold adsorption phenomena were confirmed by the comparative FT-IR spectroscopic characterization studies of fresh resin and gold loaded resin. Elution tests were carried out for the elution of gold from the gold loaded resin using various ratio mixtures of acetone and 1.0 M HCl. An elution efficiency of 96.96% gold was achieved at an acetone-to-acid ratio of 9. In this condition, gold-enriched solution containing 7,240 mg gold/ L was obtained. The maximum elution of gold was found to be 99.33% using pure acetone in a contact time of 30 minutes. The data obtained will be useful to simulate the continuous gold adsorption process within a column.

Highly optically selective and electrochemically active chemosensor for copper (II) based on triazole-linked glucosyl anthraquinone

A novel triazole-linked acetyl-β- N-glucosyl anthraquinone 1 was conveniently synthesized through one-step click chemistry. The functionalized glycoconjugate ( 1) exhibited a remarkable blue shift absorption and quenching fluorescence in the presence of trace amounts of Cu 2+, presumably attributable to intramolecular charge transfer (ICT), which also displayed high selectivity over a series of other metal cations tested in acetonitrile. The result yielded by fluorescence spectroscopy titration suggested a 2:1 ligand-to-metal complex which was further demonstrated by NMR spectroscopy titration. Moreover, the addition of Cu 2+ to 1 also significantly altered its electrochemical behavior which was reflected via differential pulse voltammetry (DPV) measurements. Such optically and electrochemically detectable metal-mediated sugar derivatives could be further used as biosensors for the recognition of multivalent carbohydrate-protein interactions.

Fabrication of rare-earth/quantum-dot nanocomposites for color-tunable sensing applications

We developed a new fluorescent nanocomposite by using a layer-by-layer approach to link NaYF4:Ce,Tb rare-earth (RE) nanocrystals and CdSe/ZnSe semiconductor quantum dots (QDs) with opposite charges. Under ultraviolet light excitation, the nanocomposites exhibited both the green Tb emission centered at 550 nm, and the red QD emission at 650 nm. Sensing applications showed that the red QD emission was quenched by trace amount of Cu2+ (or Ag+) ions due to the ion displacement mechanism, while the green RE emission kept constant. Thus, the nanocomposites with the decreased QD/RE emission intensity ratio and changed fluorescence output color provided a visible “indicator” to detect metal ions quantificationally. In comparison with single emission materials, the dual emission nanocomposites can be a more reliable probe for various sensing applications.

<b>Application of Triton X-100 coated poly vinyl chloride as new solid phase for preconcentration of Fe<sup>3+</sup>, Cu<sup>2+</sup> and Zn<sup>2+</sup> ions and their flame atomic absorption spectrometric determinations</b>

A selective, sensitive and efficient method for preconcentration of trace amounts of Cu(II), Fe(II) and Zn(II) ions based on the uptake of their complexes with 3-((indolin-3-yl)(phenyl)methyl)indoline (IYPMI) loaded on Triton X-100 coated poly vinyl chloride has been reported. The influences of the analytical parameters including pH, ligand amount, surfactant type and concentration, eluting condition and sample volume on metal ions recovery were investigated. The method has been successfully applied for the extraction of these ions content in some real samples of soil and plants. The extraction efficiency was > 97% with low relative standard deviation (RSD KEY WORDS : Surfactant coated PVC, Atomic absorption spectrometry, Solid phase extraction Bull. Chem. Soc. Ethiop. 2010 , 24(1), 11-20.

Determination of trace copper in food samples by flame atomic absorption spectrometry after solid phase extraction on modified soybean hull

Soybean hull was chemically modified with citric acid and used as a solid phase extraction adsorbent for the determination of trace amounts of Cu 2+ in food samples by flame absorption spectrometry (FAAS). The effect of pH, sample flow rate and volume, elution flow rate and volume and co-existing ions on the recovery of the analyte were investigated. The results showed that Cu 2+ could be adsorbed on the modified soybean hull at pH 8.0 and eluted by 2.0 mL of 1.0 mol L −1 HCl. Under the optimized conditions, the adsorption capacity of modified soybean hull was found to be 18.0 mg g −1 for Cu 2+. The detection limit of the proposed method was 0.8 ng mL −1 for Cu 2+ with an enrichment factor of 18. The analytical result for the certified reference tea sample (GBW07605) was in a good agreement with the certified value. The proposed method has also been successfully applied to the determination of trace Cu 2+ in dried sweet potato, lake water and milk powder, the recovery of Cu 2+ for spiked samples was between 91% and 109.6%.

A highly sensitive and selective fluorescentCu2+ sensor synthesized with silica nanoparticles

A novel fluorescent nanosensor for the determination ofCu2+ was synthesizedwith N-(quinoline-8-yl)-2-(3-triethoxysilyl-propylamino)-acetamide (QlOEt) grafted onto the surfaceof silica nanoparticles (SiNPs) using the reverse microemulsion method. Spherical SiNPs wereused as substrate and QlOEt was used simultaneously as the binding and readout system forCu2+. This sensor has been realized as a highly sensitive and selectivetechnique for the detection and quantification of trace amounts ofCu2+. The probe exhibits a dynamic response range forCu2+ from2.0 × 10−6 to2.0 × 10−5 M, with adetection limit of 3.8 × 10−7 M. Other alkali, alkaline earth, and transitional metal ions includingLi+,K+,Mg2+,Ca2+,Sr2+,Mn2+,Zn2+,Mo6+,Pb2+,Ag+ had no significantinterference on Cu2+ determination. Poisonous and flammable reagents are avoided during the synthesis of thisnanosensor. Therefore the strategy explored in this work can be extended to the synthesisof other chemo- and biosensors for direct detection of specific targets in an intracellularenvironment.

Prevention of CaCO 3 scale formation by trace amounts of copper (II) in comparison to zinc (II)

The current paper describes the influence of trace amounts of Cu 2+ ions on the precipitation of calcite in an aqueous and supersaturated CaCO 3/NaCl system and in natural water of moderate hardness. Furthermore the influence of Zn 2+ ions on CaCO 3 precipitation in the CaCO 3/NaCl system was examined and the results were compared. The resulting reduction of the Ca 2+ concentration was recorded as a function of time by measuring the electric conductivity and the pH value. Because of the metal species present in the solution, two competing processes take place. Neutral CuCO 3 0(aq) and ZnCO 3 0(aq) complexes are adsorbed onto the active growth sites of the CaCO 3 surface and ,thus, further crystal growth is inhibited. As a result of nucleation catalysis, Cu(OH) 2 particles cause the accelerated formation of CaCO 3 nuclear crystals, which counteracts the inhibition process. At Cu 2+ concentrations > 1.40 mg/L, Cu(OH) 2 is transformed into stable and crystalline malachite, at which no catalysed nucleation can take place. This results in a significant increase of the induction period and inhibition, while the efficiency attained is about 90% for Cu 2+ contents > 2.00 mg/L. For an addition of Zn 2+ ions, ZnCO 3 is precipitated and acts as strong accelerator of heterogeneous nucleation of CaCO 3, resulting in an enhanced growth rate which dominantly counteracts the inhibition effect. The results may be explained, that copper ions are more effective for scale prevention than zinc ions.

A preconcentration procedure for copper, nickel and chromium ions in some food and environmental samples on modified Diaion SP-850

A sensitive and simple method for the simultaneous preconcentration of trace amount of Cu 2+, Ni 2+ and Cr 3+ ions in some real samples has been reported. In this method these elements are adsorbed as respective complex with Bis(2-hydroxyacetophenone)-1,2-propanediimine (BHAPPDI) on Diaion SP-850 and the retained metal ions are eluted using 8 ml of 4 M nitric acid. The influences of the analytical parameters including pH, solid phase ingredients amount and condition of eluting solution and sample volume were investigated. The effects of matrix ions on retentions of the analytes were also examined. The recoveries of analytes were generally higher than 90% with a relatively low RSD. The method has been successfully applied for these metal ions contents evaluation in some food and environmental samples.

Preconcentration of Cu(II), Fe(III) and Pb(II) with 2-((2-aminoethylamino)methyl)phenol-functionalized activated carbon followed by ICP-OES determination

A procedure for separation and preconcentration trace amount of Cu(II), Fe(III) and Pb(II) by 2-((2-aminoethylamino)methyl)phenol-functionalized activated carbon (AC-AMP) packed column has been proposed. Under the optimized conditions (pH 4, flow rate 2.0 mL min(-1)), Cu(II), Fe(III) and Pb(II) were retained on the column, then quantitatively eluted by 2 mL 1 mol L(-1) nitric acid solution and determined by inductively coupled plasma-optical emission spectrometry (ICP-OES). The tolerance limits of electrolytes were very high. The adsorption capacity of AC-AMP was found to be 12.1, 67.1, and 16.2 mg g(-1) for Cu(II), Fe(III), and Pb(II), respectively. According to the definition of International Union of Pure and Applied Chemistry, the detection limits (3 sigma) of this method for Cu(II), Fe(III) and Pb(II) were 0.27, 0.41 and 0.16 microg L(-1), respectively. The relative standard deviation under optimum conditions is less than 3.0% (n=11). The proposed method has been validated by analyzing a certified reference material and successfully applied to the preconcentration and determination of Cu(II), Fe(III), and Pb(II) in actual samples with satisfactory results.

A highly sensitive and selective fluorescent sensor for the determination of copper(II) based on a schiff base

A highly sensitive and selective optical sensor for the determination of trace amounts of Cu 2+ based on fluorescence quenching has been developed. The sensing membrane was prepared by immobilization of a novel fluorescent Schiff base ligand 4-(1-phenyl-1-methylcyclobutane-3-yl)-2-(2-hydroxy-5-romobenzylidene)aminothiazole, on polyvinlyl chloride. The novel sensor, which has a linear range of 1.0 × 10 −8 – 5.7 × 10 −4 mol L −1 for Cu 2+ ions with a detection limit of 8.8 × 10 −9 mol L −1 (0.56 μg L −1), is fully reversible and the response time ( τ 90 ) was approximately 2.5 min. The optode was highly selective and can readily be regenerated by treatment with 10 −2 mol L −1 HCl. The accuracy of the proposed sensor was confirmed by analyzing standard reference materials of natural water and peach leaves. The sensor was successfully applied for the determination of copper in tap water and tea samples.

Determination of Trace Amounts of Cu2, Ni2, and Mn2 Ions After Preconcentration onto PAN-Immobilized Organo Nanoclay as a New Sorbent

The application of organo nanoclay 1-(2-pyridylazo)-2-naphthol (PAN)-immobilized as a new, easily prepared, and stable solid sorbent for preconcentration of trace amounts of Cu2+, Ni2+, and Mn2+ ions in aqueous solution is presented. The organo nanoclay was prepared by adding tetradecyldimethylbenzylammonium chloride onto montmorillonite and then saturating with PAN. A simple, rapid, selective, sensitive, and economical method was developed for the simultaneous separation of trace amounts of copper, nickel, and manganese in aqueous medium using PAN as an analytical reagent. The sorption was quantitative in the pH range of 6-9.5, and quantitative desorption occurred instantaneously with 5.0 mL 3 M HNO3. Linearity was maintained at 0.26-37 ng/mL for copper, 1-52 nglmL for nickel, and 0.2-21 ng/mL for manganese in the original solution. The detection limits were 0.04 ng/mL for Cu(II), 0.15 ng/mL for Ni(II), and 0.03 ng/mL for Mn(II) in the original solution (2delta(bl); delta = standard deviation and bl = blank). Various parameters, such as the effect of pH, breakthrough volume, and interference of a large number of anions and cations, have been studied, and the proposed method was used to determine these metal ions in water and standard samples. Determination of these metal ions in standard samples showed that the proposed method has good accuracy.

Preparation of Well-Defined Core−Shell Particles by Cu2+-Mediated Graft Copolymerization of Methyl Methacrylate from Bovine Serum Albumin

Small well-defined core-shell poly(methyl methacrylate)-bovine serum albumin (PMMA-BSA) particles have been prepared in a direct one-step graft copolymerization of MMA from BSA at 75 degrees C in water with a trace amount of Cu2+ (5 microM). Initially, BSA generates free radicals and acts as a multifunctional macroinitiator, which leads to the formation of an amphiphilic PMMA-BSA grafting copolymer. Such formed copolymer chains act as a polymeric stabilizer to promote further emulsion polymerization of MMA inside, resulting in surfactant-free stable core-shell particles, confirmed by a transmission electron microscopic (TEM) analysis. The PMMA-BSA copolymers as well as PMMA homopolymer inside the particles were isolated by Soxhlet extraction and characterized by Fourier transform infrared spectroscopy (FT-IR) and thermogravimetry (TG). The highest grafting efficiency was approximately 80%. Effects of the reaction temperature, the MMA/BSA ratio, and the concentrations of Cu2+ and BSA on such core-shell particle formation have been systematically studied. Due to their inert PMMA core and biocompatible BSA shell, these small polymer particles are potentially useful in biomedical applications.

Natural Aging in Mg-Zn(-Cu) Alloys

Natural aging in Mg-Zn-Cu alloys results in a significant hardening due to the formation of a high number density of shearable precipitates. For alloys containing Zn and Cu in the compositional ranges of both cast and wrought alloys (Zn = 2 to 2.4 at. pct, and Cu = 0.15 to 1.2 at. pct), hardening produced by natural aging (T4) for 4 to 8 weeks (91 to 104 VHN) almost equals that produced by artificial aging (93 to 109 VHN). The density of the precipitates in the T4 condition of Mg-Zn-Cu alloys was found to be of the order of precipitate density in a typical aged aluminum alloy (1024 precipitates/m3). An addition of even a trace amount of Cu to Mg-Zn alloy enhances the nucleation of the precipitates and accelerates the kinetics of precipitation, in particular during natural aging. This is believed to be a result of the enhanced favorable interaction between Cu, Zn, and vacancies. The strengthening is produced mainly by the formation of a very high density of the coherent disc-shaped Guinier–Preston 1 (GP1) zones and the prismatic precipitates perpendicular to the magnesium basal plane.