Trace Amounts Of Cadmium Ions Research Articles

Electrochemical determination of cadmium ions in biological and environmental samples using a newly developed sensing platform made of nickel tungstate-doped multi-walled carbon nanotubes

Simple and rapid analysis of cadmium ion in environmental and biological samples is of great importance due to the severe toxicity caused by this heavy metal. In the present work, nickel tungstate (NiWO4) dispersion was mixed with multi-walled carbon nanotubes (MWCNTs) to obtain a homogenous composite of (NiWO4/MWCNTs) which was assigned as carbon paste electrode modifier. The composite was fully characterized using various characterization techniques including X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), Thermo-Gravimetric Analysis (TGA) and Fourier Transform InfraRed (FTIR). The electrochemical redox reactions of cadmium (II) ions at the modified electrode interface were investigated using cyclic voltammetry (CV), differential pulse voltammetry (DPV), and linear sweep voltammetry (LSV). Effective parameters on the electro-analysis assay performance including the electrode composition, types of electrolyte, scan rate and pH were tested to achieve the best effective optimum conditions. Accordingly, a linear relation of cadmium ions was achieved in the concentration range 50–450 µM with limit of detection of 0.12 µM. Besides, the proposed electrode was successfully used to monitor trace amounts of cadmium ions in various real samples.Graphical abstractSchematic illustration of synthesis process of NiWO4/MWCN nanocomposite and its application as high-performance cadmium ion sensors

Magnetic solid phase preconcentration of cadmium in water samples using sulfonic acid functionalized Kit-6 magnetite mesoporous nanocomposites followed by flame atomic absorption spectrometry

In this study, a simple and sensitive extraction method has been developed for preconcentration of trace amounts of cadmium ions using Kit-6 magnetite mesoporous nanocomposites (MMNCs) functionalized with sulfonic acid groups as adsorbent in solid phase extraction followed by flame atomic absorption spectrometry. For this purpose, the Kit-6 mesoporous silica was chemically synthesized on the surface of silica-coated magnetite core and functionalized by sulfonic acid groups to obtain Fe3O4@SiO2@Kit-6-SO3H. The synthesized nanocomposites were characterized by XRD, SEM, VSM and EDX methods. Various parameters affecting adsorption/desorption efficiencies were investigated using Taguchi orthogonal array design. The maximum extraction efficiency of cadmium ions was obtained at pH = 8, sorbent weight = 0.1 g, ionic strength = 0, stirring time = 15 min, sample volume = 100 mL, time of desorption = 5 min, concentration and volume of HCl solution as desorption solvent 0.1 M and 3 mL, respectively. The linear dynamic range, limit of detection, enhancement factor and relative standard deviation (RSD %) of the proposed method were obtained as 0.5–100 µg L−1 (R2 = 0.9982), 0.4 µg L−1, 26.9 and 3.5%, respectively. Finally, the study of proposed MMNC adsorbent for real sample and investigating the interference potential of foreign ions successfully confirmed the ability of MMNCs for preconcentration and determination of trace levels of cadmium ions.

Extraction of trace amounts of cadmium in fish and mollusk by Fe3O4@N-carbon quantum dots as adsorbent

The extraction of trace amounts of cadmium ions in fish and mollusk was investigated using magnetic N-doped carbon quantum dots as adsorbent. The characterization of the adsorbent was performed using Fourier transform infrared spectroscopy, UV–Vis spectroscopy, X-ray diffraction spectrometry, vibrating sample magnetometer and transmission electron microscopy. Important parameters, with effective role on extraction process were optimized in three levels by central composite design. The parameters including extraction time (5, 35, 65 min), amount of the magnetic sorbent (10, 30, 50 mg) and pH (3, 5, 7) were recognized as the major factors in adsorption process and optimized. The variables including type (HCl, HNO3, HCl/thiourea, HNO3/thiourea), volume (1, 3, 5 mL) and concentration of desorption solvent (0.01, 0.5, 1 mol L−1), and desorption time (1, 5.5, 10 min) were optimized in desorption process. Under the optimum conditions (pH of 6.30; extraction time of 5 min; adsorbent amount of 10 mg; desorption solvent volume of 1.5 mL; desorption time of 5 min; desorption solvent concentration of 0.5 mol L−1), the adsorption capacity was 246 mg g−1. The detection (S/N = 3) and quantitation limits of the method were found to be 0.06 and 0.2 μg L−1, respectively. The method was also successfully used for the determination of Cd2+ in fish and mollusk samples with satisfactory recoveries (≥ 97.4%).

Determination of Trace Amounts of Cadmium Ions in Water and Plant Samples Using Ligand-Less Solid Phase Extraction-Based Modified Co3O4 Nanoparticles

ABSTRACTIn this study, a new Co3O4 nanoparticles (NPs) coated with sodium dodecyl sulphate (SDS) is developed for preconcentration of trace amounts of cadmium ions (Cd 2+) as a prior step to its determination by flame atomic absorption spectrometry (FAAS). The effects of various parameters, including pH of sample solution, amount of sorbent, flow rates of solution and eluent, sample volume, type, and least amount of the eluent for elution of the Cd 2+ from Co3O4 NPs were studied and optimized. Experimental conditions for effective separation of trace levels of the Cd 2+were optimized with respect to different experimental parameters in Column method. Under the best experimental conditions, the calibration curve was linear in the range of 1.0–500.0 ng.mL−1 of cadmium (Cd) with R2 = 0.999. The detection limit was 0.4ng.mL−1 in the original solution (3Sb/m) and the relative standard deviation for eight replicate determination of 0.1µg.mL−1 Cd was ±2.1%. The method was validated by the analysis of a certified reference material with the results being in agreement with those quoted by manufactures. The developed method was successfully applied to the extraction and determination of Cd in water and food samples with satisfactory results.

Synthesis of an ion-imprinted sorbent by surface imprinting of magnetized carbon nanotubes for determination of trace amounts of cadmium ions

The authors report on the preparation of sol-gel coated magnetized carbon nanotubes whose surface were imprinted with Cd2+ ions and the application of these materials on selective preconcentration of Cd2+ ions in different water samples. Fe3O4 particles and tetraethyl orthosilicate were used as a magnetic ingredient and as a surface modifier for the carbon nanotubes, respectively. The Cd2+-imprinted polymer was prepared by grafting copolymerization of Cd2+ ions as template, methacryloylsulfamethizole and 2-vinylpyridine as polymerizable ligands, methacrylic acid as functional monomer, and ethyleneglycoldimethacrylate as crosslinker. The resulting magnetic nanoparticles were characterized by Fourier transform infrared spectrometry, the Brunauer-Emmett-Teller method, and by scanning electron microscopy. Isothermal absorption, absorption kinetics and selectivity were studied in detail. The experimental conditions were optimized. Figures of merit include (a) a maximum adsorption capacity of 81 mg·g−1; (b) relative selectivity coefficients of 2.41, 2.36, 1.41, 1.66, and 1.70 for Cd2+/Ni2+, Cd2+/Co2+, Cd2+/Zn2+, Cd2+/Cu2+, and Cd2+/Pb2+, respectively; (c) a detection limit of 0.29 ng·mL−1, (d) an enrichment factor of 55.5; (e) an intra-day precisions of 1.13%; and (f) an inter-day precision of 1.39%. The method was successfully applied to the determination of cadmium in spiked samples including feed water of an ammonia production unit, tap water, industrial waste water from a petrochemical plant, river water from the Garrahi River, bay water from Khor Musa, and marsh water from the Shadegan wetland.

Solid phase extraction of trace amounts of cadmium(II) ions in water and food samples using iron magnetite nanoparticles modified by sodium dodecyl sulfate and 2-mercaptobenzothiazole.

A new, simple and rapid method for solid phase extraction and preconcentration of trace amounts of cadmium ions using 2-mercaptobenzothiazole/sodium dodecyl sulfate immobilized on magnetite nanoparticles (MBT-SDS-MNPs) was proposed. The method is based on the extraction of cadmium ions via complexation with MBT immobilized on SDS-coated MNPs and their determination by flame atomic absorption spectrometry. The effects of different parameters - pH; eluent type, concentration and volume; amounts of salt and adsorbent; contact time and interfering ions - on the adsorption of cadmium ions were studied. Under optimized conditions, the calibration curve was linear in the range of 10-5,000 μg L-1. Detection limit and relative standard deviation of the proposed method were 0.009 μg L-1 and 2.2%, respectively. The adsorption data were analyzed by Langmuir and Freundlich isotherm models and a maximum adsorption amount of 24.80 mg g-1, a Langmuir adsorption equilibrium constant (b) of 4.62 and Freundlich constants Kf and n of 6.075 mg1-1/n L1/n g-1 and 2.391, respectively, were obtained. Finally, this adsorbent was successfully used for extraction of cadmium from water and food samples.

Use of Modified γ-Alumina Nanoparticles for the Extraction and Preconcentration of Trace Amounts of Cadmium Ions

We used γ-Al2O3 nanoparticles coated with sodium dodecyl sulfate–4-(2-pyridylazo)resorcinol (SDS–PAR) as an innovative sorbent for the extraction and preconcentration of trace amounts of cadmium cations. The properties of the prepared sorbent were examined by scanning electron microscopy. The effects of different parameters towards the separation and preconcentration of trace amounts of cadmium ions, such as the quantity of sorbent, the pH value, and choice of solvent for recovery of the sorbent, were investigated. Under optimum operating conditions, a cadmium ion enrichment factor of 20 was obtained using 10.0 mL of sample. The detection limit of this method for CdII cations was 0.2 ng mL–1 (n = 7) within a linear range of 0.6–340 ng mL–1 and a relative standard deviation of 1.8 % (n = 10). The method was effectively applied to the analysis of cadmium ions in food and herbal and water samples.

Magnetic stirring-assisted dispersive liquid–liquid microextraction in narrow neck glass tube for determination of cadmium in water, fruit and vegetable samples using response surface methodology

AbstractNarrow neck glass tube-magnetic stirring-assisted dispersive liquid–liquid microextraction for extraction and preconcentration of trace amounts of cadmium ions as ammonium pyrrolidine dithiocarbamate complex was developed. In this method, a cloudy state is formed in a homemade glass syringe by magnetic stirring. Afterward the organic phase on top of the solution was transferred into narrow neck by moving the piston upwards, and withdrawn by the syringe for conventional injection to flame atomic absorption spectrometry. The experimental conditions were optimized by Plackett–Burman and Box–Behnken design methods. Under the optimum conditions (pH 5.5, chelating agent = 1 × 10−5 mol L−1, sodium chloride (0.04% w/v), extraction solvent volume = 250.0 μL, stirrer rate = 1,200 rpm, and extraction time = 10 min), the calibration graph was linear over the range 10–1,000 μg L−1 and the limits of detection was 1.4 μg mL−1. The relative standard deviation was 1.15% (n = 10, C = 100 μg L−1) and the enrichment ...

Application of multiwalled carbon nanotubes modified by diphenylcarbazide for selective solid phase extraction of ultra traces Cd(II) in water samples and food products

A novel sorbent for separation of cadmium ions was prepared by functionalizing multiwall carbon nanotubes with diphenylcarbazide and underutilised to develop a solid-phase extraction method to separate and concentrate trace amounts of cadmium ions from some real samples by flame atomic absorption spectrophotometry measurements. The optimum experimental conditions such as pH, flow rates, type and the smallest amount of eluent for elution of cadmium ions, break through volume and effect of coexisting ions on the separation and determination of cadmium ions were evaluated.In the proposed method, the extraction efficiency for cadmium ions were greater than 97% and limit of detection (LOD) was 0.05ngmL−1. The preconcentration factor was 360 for cadmium and the relative standard deviation (RSD) of the method was 2.4%. The adsorption capacity of the modified MWCNT was 86mgg−1 for cadmium ions. Validation of the outlined method was performed by analysing certified reference material soil (NCS DC 73323). The practical applicability of the developed sorbent was examined in some real samples.

Flame Atomic Absorption Determination of Trace Amounts of Cadmium After Preconcentration Using a Thiol-Containing Task-Specific Ionic Liquid

Dispersive liquid-liquid microextraction (DLLME) based on a task-specific ionic liquid (TSIL) was developed for the extraction and preconcentration of trace amounts of cadmium from aqueous samples, followed by flame atomic absorption spectrometry (FAAS) determination. In the proposed approach, cadmium ions are extracted from aqueous samples using small volumes of trioctylmethylammonium thiosalicylate (TOMATS) dissolved in acetone. TOMATS is a thiol-containing TSIL that can form metal thiolate complexes due to the chelating effect of the ortho-positioned carboxylate group relative to the thiol functionality. The main parameters affecting the performance of DLLME based on TSIL, such as pH, amount of TOMATS, extraction time, injection volume, salt addition, and centrifugation time, were optimized. Under optimum conditions, an LOD of 1.16 ng/mL and a good RSD of 1.8% at 60.0 ng/mL were obtained (n=7). The proposed method was applied to tap water, wastewater, well water, and milk samples. The results showed that DLLME based on TSIL combined with FAAS is a rapid, simple, sensitive, selective, low cost, volatile organic solvent-free, and efficient analytical method for the separation and determination of trace amounts of cadmium ions.