Determination Of Trace Copper Research Articles

Indirect Determination of Trace Copper(II) by Adsorptive Stripping Voltammetry with Zincon at a Carbon Paste Electrode

AbstractTraces of copper(II) can be determined by adsorptive stripping voltammetry using 2‐carboxy‐2′‐hydroxy‐5′‐sulfoformazyl benzene (Zincon) as complex forming reagent. First in phosphate buffer pH 6.4, copper(II)‐Zincon complex was adsorbed on carbon paste electrode (CPE) with an accumulation potential of 0.6 V. Following this, adsorbed complex was oxidized and detected by differential pulse voltammetric (DPV) scan from 0.6 to 1.0 V. The effective parameters in sensor response were examined. The detection limit (DL) of copper(II) was 1.1 μg/L and relative standard deviations (RSDs) for 10 and 200 μg/L Cu(II) were 1.81 and 1.03%, respectively. The calibration curve was linear for 2–220 μg/L copper(II). The resulting CPE does not use mercury and therefore, has a positive environmental benefit. The method, which is reasonably sensitive and selective, has been successfully applied to the determination of trace amount of copper in water and human hair samples.

Cloud point extraction for the determination of trace copper in water samples by flame atomic absorption spectrometry

Cloud point extraction has been used for preconcentration of trace amount of copper. The analyte was complexed with 1,2-dihydroxyanthraquinone-3-sulfonic acid sodium salt, and octylphenoxypolyethoxyethanol was added as a surfactant. The effects of experimental conditions such as pH, concentration of chelating agent and surfactant, equilibration temperature and time on cloud point extraction were studied. Under the optimum conditions, preconcentration of a 12 mL sample solution permitted the detection of 1.07 ng mL−1 of copper with an enrichment factor of 21. The method was applied to the determination of trace copper in water samples.

Determination of copper in biological samples by flame atomic absorption spectrometry after precipitation with Me-BTAP

A simple and sensitive method was developed for determination of trace copper by direct precipitation preconcentration and detection with Flame Atomic Absorption Spectrometry (FAAS). The reagent 2-[2'-(6-methyl-benzothiazolylazo)]-4-aminophenol (Me-BTAP) was used as precipitating agent. The experimental conditions for the quantitative precipitation of copper, such as pH, amount of reagents, temperature and the effect of diverse ions on the precipitation have been investigated. It was found that copper is quantitatively extracted (> or =95%) and the method provides a sensitivity enhancement of 40-fold for a 10 ml sample volume with a detection limit of 0.5 microg l(-1). The proposed method was successfully applied for the determination of trace copper in water, urine and biological samples.

Determination of trace copper in water samples by flame atomic absorption spectrometry after preconcentration on a phosphoric acid functionalized cotton chelator

This paper reports the preparation of a phosphorylated cotton chelator (PCC) by solid phase esterification of phosphoric acid (PA) onto defatted cotton fibres using urea as the catalyst. The synthesized PCC was employed for the preconcentration of copper from water samples prior to its determination by flame atomic absorption spectrometry (FAAS). The preconcentration of copper was studied under both batch and column techniques. The pH range for the quantitative preconcentration of copper was 4.0-7.0. The sorption time required for each sample was less than 30 min by the batch method. The copper sorption capacity of the PCC was found to be 15.3 mg/g at the optimum pH value. Elution with 1.0 mol dm-3 hydrochloric acid was found to be quantitative. Feasible flow rates of the copper solution for quantitative sorption onto the column packed with PCC were 0.5-4.0 ml min-1, whereas the optimum flow rate of the hydrochloric acid solution for desorption was less than 1.5 ml min-1. An 80-fold preconcentration factor could be achieved under the optimum column conditions. The tolerance limits for common metal ions on the preconcentration of copper and the number of times of column reuse were investigated. The proposed method was successfully applied for the preconcentration and determination of trace copper in natural and drinking water samples by FAAS.

Determination of trace copper (II) in water samples by kinetic-spectrophotometry

A new kinetic-spectrophotometric method is proposed for the determination of copper (II). The method is based on the catalytic effect of copper (II) on the oxidation of weak acid brilliant blue dye (RAWL) by hydrogen peroxide. The copper (II) can be determined spectrophotometrically by measuring the decrease of absorbance of RAWL at λ = 626 nm using the fix-time method. The optimum reaction conditions are as follows: pH 7.20, buffer solution NaOH-KH2PO4, RAWL (200 mg L−1) 5.00 mL, H2O2 (30%) 0.50 mL, reaction temperature 80°C and reaction time 20 min. The linear range of this method is between 0 μgL−1 and 12 μgL−1 and the limit of detection is 0.011 μgL−1, the relative standard deviation (RSD) in five replicate determinations for 2 and 8 μgL−1 copper (II) are 3.2% and 2.3%, respectively. Twenty ions do not interfere in the determination of copper (II). The method has been applied satisfactorily to the determination of copper (II) in freshwater samples (tap water and Yellow River water from Lijin, Shandong, China) and seawater samples (from the South China Sea), the recovery rates are 98.0%, 102.5% and 96.0%, respectively.

Study on Preconcentration of Trace Copper Using Microcrystalline Triphenylmethane Loaded with Malachite Green

AbstractThe paper describes a novel method for copper preconcentration using microcrystalline triphenylmethane loaded with malachite green prior to the determination by the flame atomic absorption spectrometry (FAAS). Under the optimum conditions, Cu(II) can be totally adsorbed on the surface of microcrystalline triphenylmethane, and completely separated from Pb(II), Cd(II), Co(II), Cr(III), Ni(II), Mn(II), Fe(III) and Al(III) by controlling acidity. The preconcentration factor of this proposed method is 200. The recovery is in a range of 97.5%–105%. The relative standard deviation (RSD) is not beyond 3.0%. The proposed method has been successfully applied to the determination of trace copper in various water samples with satisfactory results.

Preparation for nitrocellulose membrane-poly (vinyl alcohol)-ionic imprinting and its application to determine trace copper by room temperature phosphorimetry

Nitrocellulose membrane-poly (vinyl alcohol)-ionic imprinting (NCM-PVA-I-I) was prepared using Cu 2+ as template. The cavity in NCM-PVA-I-I matched Cu 2+ very well and the selectivity was high. Cu 2+ entered the cavity and then could form ionic association ([Cu 2+]·[(Fin −) 2]) with the anion of fluorescein (Fin −) outside the cavity by electrostatic effect. [Cu 2+]·[(Fin −) 2] could emit strong and stable room temperature phosphorescence on NCM-PVA-I-I. Its Δ I p was proportional to the content of Cu 2+. Based on the above facts, a new method for the determination of trace copper by solid substrate-room temperature phosphorimetry (NCM-PVA-I-I-SS-RTP, SS-RTP is the abbreviation of solid substrate-room temperature phosphorimetry) using NCM-PVA-I-I technique has been established. The linear range of this method was 2.00–144.00 fg Cu 2+ spot −1 (sample volume: 0.40 μL spot −1, corresponding concentration: 5.00–360.00 pg mL −1), and the detection limit calculated by 3Sb/ k was 0.43 fg Cu 2+ spot −1 (corresponding concentration: 1.1 × 10 −12 g mL −1, n = 11). Samples containing 2.00 and 144.00 fg Cu 2+spot −1 were measured, respectively, for seven times and R.S.D.s were 3.5% and 4.7%. NCM-PVA-I-I-SS-RTP could combine very well the characteristics of both the high sensitivity of SS-RTP and the high match and selectivity of NCM-PVA-I-I, and it was rapid, accurate, sensitive and with good repeatability. It has been successfully applied to determine trace copper in human hair and tea samples.

Determination of Trace Copper by Fluorescence Spectrophotometry Based on Cu(DP)2+ and Cu‐4.0‐Generations Polyamidoamine Dendrimers Catalyze Cu2+ to Oxidize Fluorescein

Fluorescein can emit strong and stable fluorescence. Cu2+ can oxidize fluorescein, which causes the fluorescence signal to diminish. Cu(DP)2+ (DP refers to α,α′‐dipyridyl) and Cu‐GPD‐4.0 (GPD‐4.0 refers to 4.0‐generations polyamidoamine dendrimers) both can catalyze Cu2+ to oxidize fluorescein, which causes the fluorescence signal to diminish sharply. The ΔF is directly proportional to the content of copper. Based on the facts above, a new catalytic fluorescence spectrophotometry for the determination of trace copper using Cu(DP)2+ and Cu‐GPD‐4.0 was established. The linear range of this method is 0.040–28 pg mL−1. The regression equation for working curve is ΔF=209.5+14.39 CCu 2+ (pg mL−1), n=7; correlation coefficient is 0.991. The detection limit of this method is 1.0×10−14 g mL−1. After replicate measurement times, RSDs are 3.1% and 4.2% for samples containing 0.040 and 28 pg mL−1 Cu2+, respectively. This method is rapid and precise with high sensitivity and good repeatability. The method has been applied to the determination of trace copper in tea and human hair with satisfactory results. Meanwhile, the mechanism for the determination of trace copper by catalytic fluorescence spectrophotometry using Cu(DP)2+ and Cu‐GPD‐4.0 was also discussed.

Study of spectrophotometric method for determination of trace copper after the separation and enrichment with solid phase extractant-microcrystalline phenolphthalein

A new method of using phenolphthalein loaded with 1-(2-pyridylazo)-2-naphthol (PAN) as solid phase extractant to separate and enrich trace copper in diverse water samples has been developed. The effects of different parameters, such as the amounts of PAN and phenolphthalein, stirring time, various salts and metal ions on the enrichment yield of Cu(II) have been investigated to select the experimental conditions. Under the optimum conditions, Cu(II) can be totally adsorbed on the surface of microcrystalline phenolphthalein. By controlling appropriate acidity (pH=1.0), Cu(II) is completely separated from Cd(II), Pb(II), Mn(II), Co(II), Fe(III), Ni(II), Al(III), Zn(II) and Hg(II) in the solution. The possible reaction mechanism of the enrichment of copper is discussed in detail in this paper. The detection limit of this proposed method is found to be 0.03 μg·L−1 with the enrichment factor of 200. The recovery is in a range of 96.8%–105%. The standard deviation is less than 2.5%. The proposed method has been successfully applied to the determination of trace copper in different water samples with satisfactory results.

Ultra Trace Copper Determination by Catalytic-Adsorptive Stripping Voltammetry Using an Alizarin Red S modified Graphite Electrode

Ultra Trace Copper Determination by Catalytic-Adsorptive Stripping Voltammetry Using an Alizarin Red S modified Graphite Electrode

Determination of Trace Copper by Solid Substrate–Room Temperature Phosphorescence Quenching Method Based on Lead Carboxymethyl Cellulose [Pb(CMC)2] Particles Containing Luminescent Salicyl Fluorones Molecules

Luminescent particles of lead carboxymethyl cellulose [Pb(CMC)2] that contain luminescent salicyl fluorones (SAF) {[Pb(CMC)2]‐SAF} were synthesized by sol‐gel method, using sodium carboxymethyl cellulose (NaCMC) as precursor and Pb2+ as precipitator. [Pb(CMC)2]‐SAF can emit intense and stable solid substrate–room temperature phosphorescence (SS‐RTP) on filter paper. EDTA (ethylenediaminetetraacetic acid) can chelate the Pb2+ in [Pb(CMC)2]‐SAF, causing it to decompose into aqueous soluble components PbY2–, CMC–, and SAF, and these components can react with Cu2+ to form [Cu(CMC)2]‐SAF, causing decrease of phosphorescence intensity. Based on the facts above, a new method for the determination of trace mercury by SS‐RTP quenching method was established. This method has been applied to the determination of trace copper in human hair and tea samples with satisfactory results.

Spectrophotometric determination of trace copper in water samples with thiomichlersketone

A simple and sensitive spectrophotometric method for determination of trace copper in water samples is proposed. In the presence of pH 4.6 HAc–NaAc buffer solution and surfactant polyethylene octyl phenyl ether (OP) medium, copper reacts with thiomichlersketone (TMK) to form a stable 1:4 complex. The complex Cu(II)–TMK–OP shows maximum absorbance at 500 nm with a molar absorptivity value of 5.7 × 10 4 l mol −1 cm −1. Beer's law is obeyed for copper concentrations in the range of 0–15 μg/25 ml. The average recovery of copper is between 95.8 and 106%. The method has been applied for determination of trace copper in different water samples with satisfactory results.

Determination of Copper Traces in Tequila by Anodic Stripping Voltammetry (ASV)

not Available.

Spectrofluorimetric study of the interaction of copper(II) and bis-heterocyclictriazene reagent in the presence of β-cyclodextrin

A new reagent, 1,3-bis(2-benzothiazolyl-diazoamino)benzene (BBTAB), was first synthesized and characterized by elemental analysis, 1H NMR and IR spectra. The inclusion complex of BBTAB with β-cyclodextrin (β-CD) was formed. BBTAB in the inclusion complex or alone reacts with copper(II) to form chelate complex in a slight basic medium, which results in drastic or slight fluorescence enhancement, respectively. The spectrofluorimetric method of trace amount of copper(II) based on the enhancement of inclusion complex by binding with copper(II) was established. The excitation and emission wavelengths of the BBTAB/β-CD/Cu system are 389 and 480 nm, respectively. Under optimal conditions, a linear response of BBTAB/β-CD to copper(II) is obtained in the range of 3.0 × 10 −7 to 1.0 × 10 −5 mol L −1, and the detection limit is determined to be 1.2 × 10 −8 mol L −1. The method is selective, sensitive and simple, and has been used for the determination of trace copper(II) in water samples with satisfactory results. The possible response mechanism of BBTAB/β-CD or BBTAB to copper(II) and the role of β-CD in the drastic enhancement of fluorescence of BBTAB/β-CD/Cu system have been discussed.

Evaluation of polychlorotrifluoroethylene as sorbent material for on-line solid phase extraction systems: Determination of copper and lead by flame atomic absorption spectrometry in water samples

Polychlorotrifluoroethylene (PCTFE) in the form of beads was applied, as packing material for flow injection on-line column preconcentration and separation systems coupled with flame atomic absorption spectrometry (FAAS). Its performance characteristics were evaluated for trace copper determination in environmental samples. The on-line formed complex of metal with diethyldithiophosphate (DDPA) was sorbed on the PCTFE surface. Isobutyl methyl ketone (IBMK) at a flow rate of 2.8 mL min −1 was used to elute the analyte complex directly into the nebulizer–burner system of spectrophotometer. The proposed sorbent material reveal, excellent chemical and mechanical resistance, fast adsorption kinetics permitting the use of high sample flow rates up to 15 mL min −1 without loss of retention efficiency. For copper determination, with 90 s preconcentration time the sample frequency was 30 h −1, the enhancement factor was 250, which could be further improved by increasing the loading (preconcentration) time. The detection limit (3 s) was c L = 0.07 μg L −1, and the precision (R.S.D.) was 1.8%, at the 2.0 μg L −1 Cu(II) level. For lead determination, the detection limit was c L = 2.7 μg L −1, and the precision (R.S.D.) 2.2%, at the 40.0 μg L −1 Pb(II) level. The accuracy of the developed method was evaluated by analyzing certified reference materials and by recovery measurements on spiked natural water samples.

Selective Solid-Phase Extraction of Trace Copper Ions in Aqueous Solution with a Cu(II)-Imprinted Interpenetrating Polymer Network Gel Prepared by Ionic Imprinted Polymer (IIP) Technique

An Cu(II)-imprinted interpenetrating polymer network (IPN) gel of epoxy-diethylenetriamine and methacrylic acid-acrylamide-N,N′-methylene-bis-(acrylamide) was synthesized by the ionic imprint polymer (IIP) technique. The first polymer network is formed by epoxy gelation with diethylenetriamine. The other is formed by copper methacrylate co- polymerization with acrylamide and cross-linker N,N′-methylene-bis-(acrylamide). The adsorption–desorption characteristics of the IPN gel as a highly selective solid-phase extraction (SPE) and preconcentration adsorbent for Cu2+ from aqueous solution were investigated. The experimental results show that trace Cu2+ ions can be quantitatively enriched at pH 5 with recovery >95%. The maximum static adsorption capacity of the ion-imprinted functionalized gel adsorbent was 76 mg g−1. Comparing with non-imprinted IPN gel, the imprinted IPN gel has higher adsorption capacity and selectivity for Cu2+ by the static adsorption–desorption experiment. Simultaneously, the times of adsorption equilibration and complete desorption were remarkably short. The precision (RSD) for 11 replicate adsorbent extractions of 20 ng mL−1 Cu2+ was 3.4%. The established procedure was applied to two real water samples with satisfactory results. The prepared ion-imprinted IPN gel adsorbent was shown to be promising for solid-phase extraction coupled with atomic absorption spectrometry (AAS) for the determination of trace copper in real samples. In addition, the coordination interaction of Cu2+ and functional groups of the IPN gel adsorbent was primarily discussed by FT-IR spectra.

Graphite electrodes modified by 8-hydroxyquinolines and its application for the determination of copper in trace levels

Surface modification by 8-hydroxyquinoline-5-sulfonic acid (8-HQS) or 8-hydroxyquinoline (8-HQ) on a graphite electrode through irreversible adsorption is reported in this paper. Cyclic voltammetry was used to characterize the surface behavior. The modified surface exhibited an affinity to chelating Cu(II) in the solution, forming a Cu(II) complex, which was employed for Cu(II) trace analysis. Of the metals Zn, Ni, Pb, Co, and Cd, none presented interference until excess concentration of 10 times. Significant interference could be observed from Co(II), Cd(II) and Fe(II) for an excess concentration of 100 times on the analyte. A differential pulse voltammetry, combined with a preconcentrating-stripping process and a standard addition method was used for the analysis. A detection limit for trace copper determination in water, such as 5.1´10-9 mol L-1, was obtained.

Determination of trace copper by solid substrate-room temperature phosphorescence quenching method based on activating effect of α,α′-dipyridyl on Vitamin C reducing beryllon

A new solid substrate-room temperature phosphorescence quenching method for the determination of trace copper has been established. It is based on the fact that beryllon (R) can emit strong and stable solid substrate-room temperature phosphorescence on the filter paper, and Vitamin C (Vc) reduces R to non-phosphorescent compound that leads to solid substrate-room temperature phosphorescence (SS-RTP) quenching of R, and α,α′-dipyridyl can activate copper catalyzing Vitamin C reducing R. The Δ I p of the system with α,α′-dipyridyl is 3.3 times higher than that without α,α′-dipyridyl, which shows the reaction of α,α′-dipyridyl activating copper catalyzing Vitamin C reducing R. The reducing value of phosphorescence intensity (Δ I p) is directly proportional to the content of Cu(II) in the range of 0.040–4.0 fg spot −1 (corresponding concentration: 0.10–10.0 pg ml −1, sample volume: 0.40 μl spot −1). The regression equation of working curve can be expressed as Δ I p = 69.99 + 41.00 m Cu 2+ (fg spot −1) ( r = 0.9980, n = 6), and the detection limit is 0.0088 fg spot −1(corresponding concentration: 2.2 × 10 −14 g ml −1). This sensitive and accurate method with good repeatability and high selectivity has been applied to the determination of trace copper in real samples with satisfactory results. The reaction mechanism for the determination of trace copper by solid substrate-room temperature phosphorescence quenching method based on the activating effect of α,α′-dipyridyl on Vitamin C reducing beryllon is also discussed.

Application of multiwalled carbon nanotubes as solid phase extraction sorbent for preconcentration of trace copper in water samples

The adsorption behavior of multiwalled carbon nanotubes (MWNTs) toward copper has been investigated systemically, and a new method has been developed for the determination of trace copper in water samples based on preconcentration with a microcolumn packed with MWNTs prior to its determination by flame atomic absorption spectrometry. The optimum experimental parameters for preconcentration of copper, such as pH of the sample, sample flow rate and volume, elution solution and interfering ions, have been investigated. Copper can be quantitatively retained by MWNTs in the pH range 5-8, and then eluted completely with 0.5 M HNO3. The detection limit of this method for Cu was 0.42 ng/mL, and the RSD was 3.5% at the 10 ng/mL Cu level. The method was validated using a certified reference material, and has been successfully applied for the determination of trace copper in water samples.

Sensitization of the 4f-Luminescence of Terbium with Copper Ions and Its Analytical Application

The intense sensitization of terbium luminescence with copper(II) ions was observed in the Tb–Cu mixed-metal complex of 1.5-bis(2-hydrazinocarbophenoxy)-3-oxapentane (HCPhO) with the ratio Tb : Cu : HCPhO = 1 : 1 : 1. Other d-block metals produced no sensitizing effect. The effect observed was used for the luminescence determination of trace copper in the presence of 1000-fold amounts of Mn(II), Fe(III), Co(II), Ni(II), Zn(II), and Cd(II). The accuracy of determining copper was verified by the analysis of Certified Reference Materials of zinc- and nickel-based alloys.