Determination Of Copper In Water Research Articles

Development of Micro-Column Preconcentration Method Using a Restricted-Access Poly(protoporphyrin-co-vinyl pyridine) Adsorbent for Copper Determination in Water and Milk Samples by FIA-FAAS

For years, researchers have focused on the determination of metal ions at trace levels in environmental and food samples using analytical methods that employ techniques with low cost acquisition and maintenance and without microwave-assisted acid digestion procedures or aggressive reagents. Therefore, the present study deals with the synthesis and application of a novel, restricted-access poly(protoporphyrin-co-vinyl pyridine) adsorbent to preconcentrate copper in water samples and bovine milk that have only been subjected to pH adjusting (pH 6.0) and filtration using posterior on-line determination by FAAS. Regarding macromolecules, the restricted-access property of the adsorbent was achieved using the hydrophilic compound 2-hydroxyethyl methacrylate (HEMA). This method is based on the preconcentration of Cu2+ ions using a flow-injection system which is buffered with 0.05 mol L−1 of Britton–Robinson (BR) at a pH of 6.0 and has a flow rate of 14.0 mL min−1 through a mini-column packed with 50.0 mg of adsorbent. The elution was carried out using 0.40 mol L−1 of HCl toward the FAAS detector. The developed method provided a preconcentration factor of 44.7-fold, low limits of detection (LOD) (0.90 µg L−1) and quantification (LOQ) (2.90 µg L−1), tolerance to interfering ions (95.0 and 103.0%), and intra-day and inter-day precision assessed as the RSD (percentage of relative standard deviation), which ranged from 3.08 to 4.80%. The restricted-access poly(protoporphyrin-co-vinyl pyridine) adsorbent demonstrated outstanding features to exclude macromolecules, bovine serum albumin (BSA), and humic acid (HA) from an aqueous medium. Lake water and bovine milk samples were analyzed by the proposed preconcentration method with minimal sample pretreatment (which was based mainly on pH adjusting and filtration using an analytical curve with external calibration), yielding recovery values from addition and recovery tests ranging from 91.7 to 101.9%. The developed method shows great advantages over previously published methods, avoiding the time-consuming use of concentrated acids in a microwave-assisted acid digestion procedure.

A simple and rapid technique for the determination of copper based on air-assisted liquid–liquid microextraction and image colorimetric analysis

In this study, a new, cheap, simple and rapid method for the determination of copper in water and food samples using air-assisted liquid-liquid microextraction and digital image decomposition into the primary colors Red (R), Green (G) and Blue (B) is introduced. In the proposed method, sodium diethyl-dithiocarbamate (Na-DDTC) and carbon tetrachloride (CCl4) were used as the chelating agent and extraction solvent, respectively. The digital images of the extraction phase were obtained using an Android mobile phone and analyzed using a free app (Color Grab). Then the value of the B channel was taken as the analytical signal. The effects of different parameters influencing the extraction efficiency were investigated and optimized. Under the optimal conditions, the limit of detection (LOD) and quantitation (LOQ) were 1.5 and 5 μg L-1, respectively. The repeatability of the proposed method, expressed as the relative standard deviation (RSD), was 4.53% for intra-day (n = 8, C = 100 μg L-1) and 5.66% for inter-day (n = 5) precision. The proposed method was applied for the determination of trace amounts of copper in rice, lettuce and water samples with satisfactory results validated by the Graphite Furnace Atomic Absorption Spectrometry technique.

(4-Hydroxy-2-oxo-2H-chromen-3-yl)methyl pyrrolidine-1-carbodithioate as a novel, highly selective and sensitive ligand for determination of copper in water and food samples by dispersive liquid–liquid microextraction coupled with microvolume UV–Vis spectrophotometry

In this research, a fast, simple, selective, and sensitive spectrophotometric method based on dispersive liquid–liquid microextraction (DLLME) was developed for the ultratrace determination of copper(II) using newly synthesized chromogenic reagent (4-hydroxy-2-oxo-2H-chromen-3-yl)methyl pyrrolidine-1-carbodithioate (HCDTC). The affecting factors in complexation and microextraction steps were investigated and optimized. HCDTC forms highly sensitive yellow-colored complex with copper(II) (1:4 [copper(II): ligand]) in the wide pH range which shows maximum absorbance at 445 nm. In direct determination, Beer’s law was obeyed in the concentration range from 0.1 to 5.0 mg L−1. Molar absorptivity and Sandell’s sensitivity values for Cu(II)–HCDTC complex were 1.3 × 104 and 0.0047 µg cm−2, respectively. However, by applying DLLME, a detection limit as low as 0.3 µg L−1 with preconcentration factor of 92 and relative standard deviation (n = 6) less than 3.5% were achieved. Moreover, calibration graph was linear in the range of 1.0–200 µg L−1. Finally, the proposed method was successfully applied for preconcentration and determination of the Cu(II) in some water and fruit juice samples, and satisfactory results were obtained. Accuracy and reliability of the method were also verified by GF-AAS.

Development of a dispersive liquid–liquid microextraction method for preconcentration and determination of copper in water and vegetables

ABSTRACTAccurate and reliable determination of copper in vegetables and water is often difficult because of low copper concentrations and matrix effects. A new dispersive liquid–liquid microextraction method has been developed for preconcentration of trace amounts of copper as a prior step to its determination by flame atomic absorption spectrometry. In this method, carbon tetrachloride was used as the extraction solvent and 1-(2-pyridylazo)-2-naphthol (PAN) was used as the chelating agent. The factors: type and volume of extraction solvent, volume of PAN, pH of sample solution, extraction time, and salting out effect influencing extraction efficiency of copper ions were optimized. Under optimal conditions, the calibration curve was linear in the range of 1.0–500 ng · mL−1 of copper with an R2 = 0.999. Detection limit (3Sb) was 0.3 ng · mL−1 in original solution and the relative standard deviation for eight replicate determinations of 0.1 μg · mL−1 copper was ± 1.8%. Copper is aggregated in edible parts of leafy vegetables. Metals analysis on vegetables is essential for the protection of human health and to comply with regulatory controls. Speed and ease of operation, and cost and timesaving are advantages of this method.

Development of an efficient enrichment system for copper determination in water and food samples based on p-phenylenediamine anchored magnetic titanium dioxide nanowires

ABSTRACTIn the present work, titanium dioxide nanowires (TNWs) were synthesised via hydrothermal method. Insertion of ZnFe2O4 nanoparticles to the surface of TNWs was done by sol gel combustion synthesis of the nanoparticles in the presence of the nanowires. The surface of prepared magnetic TNWs was modified by p-phenylendiamine and then it was used in preconcentration of Cu2+ ion prior to their determination by flame atomic absorption spectroscopy. The sorbent was characterised by Fourier transform infrared spectra, EDX, FE-SEM and VSM techniques. We investigated and optimised various parameters influencing the preconcentration efficiency, such as the media pH, adsorbent quantity, contact time, sample volume and elution conditions. Under optimum conditions, the analytical performance of the method was evaluated. The calibration curve was found to be linear from 10.0 to 150 μg L−1 (R2 = 0.996). Calculated limit of detection was 0.43 μg L−1 (n = 5). The estimated relative standard deviation was 2.50% (n = 5). Moreover, the maximum adsorption capacity of the sorbent was 51.5 mg g−1 and preconcentration factor was 125. Capability of developed method was proved by applying it for preconcentration of Cu2+ ion from food and water samples.

Determination of Copper in Water and Walnuts by Solid Phase Extraction and Slotted Quartz Tube Flame Atomic Absorption Spectrometry

ABSTRACTCu(II) was separated and preconcentrated using solid phase extraction and a slotted quartz tube (SQT) and determined in drinking water and walnuts by flame atomic absorption spectrometry. The procedure is based on the sorption of copper(II) on a column filled with a resin followed by elution with 5 mL of 3 mol L−1 nitric acid in the first preconcentration step. To increase the sensitivity of system, the preconcentration parameters for copper(II) were optimized. The SQT was used as the second preconcentration step to further improve the sensitivity. The enrichment factor and detection limits were 640 and 0.23 µg L−1, respectively. Another advantage of this method is the presence of a wide pH range for copper(II) sorption with high effectiveness in acidic media. The accuracy of method was confirmed by the analysis of a spinach leaves certified reference material (NIST 1570a).

Novel and Easy Accessible Method for the Estimation of Copper Spectrophotometrically in Water and Soil Samples

A simple and sensitive spectrophotometric method has been established for the determination of copper in water and soil sample. The method simply involves the chelation of Dimethylglyoxime ligand with Copper under optimal conditions. The method is based on the formation of 1:2 complexes between Copper and Dimethylglyoximine. The optimal condition for the determination of copper was established. The Beer’s law was applicable in the range 0.05 to 0.995 μg/ml. The molar extinction coefficient of the said complex was found to be 1.2 × 105 mol-1 cm-1. The method was successfully applied for the determination of Copper in the water and soil samples.

Solid-Phase Extractive Preconcentration of Trace Copper as its Calmagite Anionic Chelate using a Polyaniline Column for Flame Atomic Absorption Spectrometric Determination

A new solid phase extraction method based on the application of polyaniline as the sorbent and calmagite as the anionic chelating agent is reported for selective preconcentration of trace copper, prior to its determination by microsample injection system-flame atomic absorption spectrometry. The parameters that influence the extraction and chelate formation were optimized. The copper was retained on a polyaniline minicolumn at pH 4.0 and eluted with 2.0 mL of 3.0 mol L−1 nitric acid. Under the optimum conditions, the limit of detection, the relative standard deviation, and the preconcentration factor were 1.98 µg L−1, less than 5.4%, and 50 to 200, respectively. The method was validated through the analysis of certified reference water samples and standard addition measurements. Quantitative recoveries between 93.4% and 103.5% were obtained. The method was successfully applied to the determination of copper in water.

Determination of ultra trace amounts of copper by a multi-injection technique of electrothermal atomic absorption spectrometry after using solid-phase extraction.

A new method using a multi-injection technique combined with SPE was developed for the determination of copper (Cu) in environmental samples. The method is based on SPE of copper ions on naphthalene as its 2-(5-bromo-2-pyridylazo)- 5-diethylaminophenol (5-Br-PADAP)-ammonium tetraphenylborate complex, in the pH range 6.0-9.5, and determined by electrothermal atomic absorption spectrometry. No chemical modifier is required in the graphite furnace. The detection limit can be reduced to 1.5 ng/L using an injection volume of 25.0 μL (five 5.0 μL) without interference by the matrixes. The optimum pyrolysis and atomization temperatures were 500 and 2200°C, respectively, for the concentrated solution of Cu. The sensitivity for 1% absorption was 2.6 pg Cu. Eight replicate determinations for 0.1 μg Cu in 5.0mL dimethylformamide gave an RSD of 2.3% for a single injection and 2.7% for a multi-injection. The procedure was validated with certified reference materials and successfully applied to the determination of copper in water and plant samples.

Determination of Copper in Water by Ionic Liquid Based Microextraction and Chemiluminescence Detection

A versatile, sensitive, and green method based ultrasound-assisted, temperature-controlled, dispersive liquid–liquid microextraction with an ionic liquid and chemiluminescence detection was used for the determination of copper(II) at the ultra-trace level. After complexation by dithizone, copper(II) was extracted into the ionic liquid. Using high temperature and ultrasonic agitation, the copper complex easily migrated into the ionic liquid phase because of the larger contact area. After back extraction, the determination was performed by chemiluminescence based on the catalyzing effect of copper(II) on the decomposition of hydrogen peroxide with rhodamine B. Important parameters that affected the extraction efficiency and chemiluminescence intensity were optimized. Under the optimum conditions, a limit of detection for copper of 0.8 ng L−1 was obtained with a linear calibration relationship. The method was applied to analyze environmental water samples for copper(II) with satisfactory results.

Estimation of Measurement Uncertainties for the DGT Passive Sampler Used for Determination of Copper in Water.

Diffusion-based passive samplers are increasingly used for water quality monitoring. While the overall method robustness and reproducibility for passive samplers in water are widely reported, there has been a lack of a detailed description of uncertainty sources. In this paper an uncertainty budget for the determination of fully labile Cu in water using a DGT passive sampler is presented. Uncertainty from the estimation of effective cross-sectional diffusion area and the instrumental determination of accumulated mass of analyte are the most significant sources of uncertainty, while uncertainties from contamination and the estimation of diffusion coefficient are negligible. The results presented highlight issues with passive samplers which are important to address if overall method uncertainty is to be reduced and effective strategies to reduce overall method uncertainty are presented.

Ultra-sensitive quantification of copper in food and water samples by electrochemical adsorptive stripping voltammetry

A new electrochemical adsorptive stripping voltammetry method was developed for the determination of trace amounts of copper in food and water samples. The study of electrochemical behavior of Cu ion indicated that Cu(II) and Schiff base formed a complex in H₃BO₄-NaOH buffer solution (pH = 7.25). An accumulation potential of -100 mV (vs Ag/AgCl) was applied while the solution was stirred for 60 s. The response curve was recorded by scanning the potential, and the peak current of -0.31 V (vs Ag/AgCl) was recorded. The peak current and concentration of copper accorded with linear relationship in the range of 0.04-120 ng mL(-1). The relative standard deviation (for 12 ng mL(-1) of copper) was 1.73%, and the detection limit was 0.007 ng mL(-1). The possible interference of some common ions was studied. The proposed method was applied to the determination of copper in water, rice, wheat, tea, milk, and tomato with satisfactory results.

On-Line Determination of Trace Copper in Water Using Near-Infrared Spectroscopy and Fluidized Bed Enrichment

On-Line Determination of Trace Copper in Water Using Near-Infrared Spectroscopy and Fluidized Bed Enrichment

Determination of Copper in Water, Vegetables, Foodstuffs and Pharmaceuticals by Direct and Derivative Spectrophotometry

The quantification of copper in water, vegetables, foodstuffs, human hair and pharmaceutical samples was determined by a simple more sensitive and selective spectrophotometric method. Cu(II) forms an orange - red color complex with 5-{� -methyl-3-hydroxy benzylidene} rhodanine (5M, 3H-BR), at pH 5.5 in sodium acetate and acetic acid buffer. The maximum absorbance was measured at 430 nm. The Beer's law is obeyed in the range of (0.05 µg -13 µg/mL). The molar absorptivity ( �) and the Sandell's sensitivity of the complex were 0.6027 × 10 4 mol -1 cm -1 and 0.01054 µg cm -2 respectively. First, second and third derivative spectrophotometry were also proposed and employed successfully for the determination of copper in the supra. The performance of the present method was also evaluated in terms of RMSEP, REP and RSD, students t- test. This indicates the greater importance of the method than other methods reported in the literature.

A pre-concentration procedure employing a new imprinted polymer for the determination of copper in water

This work describes the development by response surface methodology (RSM) of a procedure for copper determination by inductively coupled plasma optical emission spectrometry (ICP OES) in water samples after extraction by copper imprinted polymer. Results of the two-level full factorial design (24) based on an analysis of variance demonstrated that only the solution pH; amount of polymer and adsorption time were statistically significant. Optimal conditions for the extraction of copper samples were obtained by using Box-Behnken design. Solution pH; amount of polymer and adsorption time were regarded as factors in the optimisation study. The working conditions were 4.6, 0.03 g and 3.5 h, for solution pH, amount of polymer; and adsorption time, respectively. Under the optimised experimental conditions, the detection limit of the proposed method followed by ICP OES was found to be 0.8 µg L−1. The relative standard deviation (RSD) was found to less than 0.81%. The pre-concentration factor was 22.5. The accuracy of the optimised procedure was evaluated by analysis of certified reference material. The method was applied to the determination of copper in water samples.

Determination of Copper in Water by Anodic Stripping Voltammetry Using Cu-DPABA–NA/GCE Modified Electrode

Determination of Copper in Water by Anodic Stripping Voltammetry Using Cu-DPABA–NA/GCE Modified Electrode

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.

Development of Dispersive Liquid-Liquid Microextraction Based on Solidification of Floating Organic Drop for the Sensitive Determination of Trace Copper in Water and Beverage Samples by Flame Atomic Absorption Spectrometry

A dispersive liquid-liquid microextraction based on solidification of floating organic droplet (DLLME-SFO) has been developed as a new approach for the extraction of trace copper in water and beverage samples followed by the determination with flame atomic absorption spectrometry. In the DLLME-SFO, 8-hydroxy quinoline, 1-dodecanol, and methanol were used as chelating agent, extraction solvent and dispersive solvent, respectively. The experimental parameters related to the DLLME-SFO such as the type and volume of the extraction and dispersive solvent, extraction time, sample volume, the concentration of chelating agent and salt addition were investigated and optimized. Under the optimum conditions, the enrichment factor for copper was 122. The method was linear in the range from 0.5 to 300 ng mL �1 of copper in the samples with a correlation coefficient (r) of 0.9996 and a limit of detection of 0.1 ng mL �1 . The method was applied to the determination of copper in water and beverage samples. The recoveries for the spiked water and beverage samples at the copper concentration levels of 5.0 and 10.0 ng mL �1 were in the range between 92.0% and 108.0%. The relative standard deviations (RSD) varied from 3.0% to 5.6%.

Separation and preconcentration system based on microextraction with ionic liquid for determination of copper in water and food samples by stopped-flow injection spectrofluorimetry

In this work, an efficient in situ solvent formation microextraction (ISFME) was combined with stopped-flow injection spectrofluorimetry (SFIS) for the determination of copper. In the proposed approach, thiamine was oxidized with copper(II) to form hydrophobic and highly fluorescent thiochrome (TC), which was subsequently extracted into ionic liquid as an extractant phase. A small amount of an ion-pairing agent (NaPF6) was added to the sample solution containing a water-miscible ionic liquid ([Hmim][BF4]) to obtain a hydrophobic ionic liquid ([Hmim][PF6]), which acted as the extraction phase. After centrifuging, phase separation was performed and the enriched analyte was determined by SFIS. ISFME is an efficient method for separation and preconcentration of metal ions from aqueous solutions with a high ionic strength. Variables affecting the analytical performance were studied and optimized. Under optimum experimental conditions, the proposed method provided a limit of detection (LOD) of 0.024μgL−1 and a relative standard deviation (RSD) of 2.1%. The accuracy of the combined methodology was evaluated by recovery experiments and by analyzing certified reference material (GBW 07605 Tea). Finally, the proposed method was successfully applied to copper determination in water and food samples.

Imprinted polymer particles for preconcentration of copper from water and biological samples

Imprinted polymer particles have been developed as a novel adsorbent for the adsorption of copper from aqueous solution. This method has received much attention in various fields because of their high selectivity for template molecules. In this work, separation of copper from water and biological samples by batch solid phase extraction based on molecular imprinting technique is presented. Copper-imprinted polymer was prepared by free radical solution polymerization in a glass tube containing CuSO4, morin, 4-vinylpyridine as a functional monomer, ethyleneglycoldimethacrylate as a cross-linking monomer, 2,2′- azobisisobutyronitrile as an initiator. The polymer block obtained was ground and sieved, and the Cu-morin complex was removed from polymer particles. The synthesized polymer particles both prior to and after leaching have been characterized by IR and X-ray diffraction studies. The effect of different parameters, such as pH, adsorption and desorption time, type and least amount of the eluent for elution of the complex from polymer were evaluated. The limit of detection of the proposed method was 0.12 μg L−1. The method was applied to the recovery and determination of copper in water and biological real samples.