Cadmium In Real Samples Research Articles

A novel potentiometric approach for the sensitive detection of cadmium in real samples using modified carbon paste electrodes

AbstractThe goal of this study was to demonstrate a novel potentiometric technique for the measurement of Cd(II) ion. A new ionophore called [5′‐(ethane‐1,2‐diylbis(sulfanediyl))bis(3‐phenyl‐4H‐1,2,4‐triazol‐4‐amine) (ESPTA)] was prepared and used as an electroactive material in the fabrication of new carbon paste electrode (CPE) for the quantification of Cd(II) ion. The paste was prepared by mixing ESPTA, graphite, graphene, and TCP or o‐NPOE as a plasticizer in different weight percent ratios. The developed electrodes I, II, III, and IV showed divalent Nernstian response of 29.80±0.05, 29.80±0.08, 29.86±±0.04 and 29.75±0.33 mV decade−1 over the concentration ranges of 1.0×10−5–1.0×10−1, 1.0×10−8–1.0×10−1, 1.0×10−6–1.0×10−1 and 1.0×10−7–1.0×10−1 mol L−1 with percentage of (2.65 ESPTA: 66.32 graphite: 31.03 TCP), (2.65 ESPTA: 13.27 graphite : 53.05 graphene : 31.03 TCP), (2.75 ESPTA: 68.68 graphite: 28.57 o‐NPOE) and (2.75 ESPTA: 13.74 graphite : 54.94 graphene : 28.57 o‐NPOE), for electrodes I, II, III, and IV, respectively. In order to improve the performance characteristics of electrodes I, II, III, and IV, response time, the effect of temperature, and pH were examined. The electrodes showed high selectivity for Cd(II) over different mono‐, di‐ or trivalent cations. These modified electrodes were applied for the determination of the concentration of Cd(II) in different real samples like Nido Milk, juice extractions and tap water samples with high percentage recovery. The F‐ and t‐test values showed that there is no statistically significant difference between the results obtained and those from the stated method of inductively coupled plasma. Low standard and relative standard deviation values, good percentage recovery, and modest detection and quantification limitations were all displayed by the electrodes. The outcomes showed the potentiometric method‘s effectiveness in detecting Cd(II) in actual samples and its potential for use in routine analysis.

A novel morphological ion imprinted polymers for selective solid phase extraction of Cd(II): Preparation, adsorption properties and binding mechanism to Cd(II)

A Cd(II) ion-imprinted polymers (SOS@Cd(II)-IIPs) with specific recognition property and high adsorption capacity was synthesized on a novel spheres-on-sphere (SOS) particle surface. Then, the obtained SOS@Cd(II)-IIPs were characterized and applied in solid phase extraction (SPE) column for the preconcentration of cadmium in real samples. The affinity constant (KITC), reaction enthalpy (ΔH), and entropy (ΔS) of Cd(II) binding to monomers (3-mercaptopropyl trimethoxysilane, MPTMS) were also determined by isothermal titration calorimetry (ITC) to analyse their adsorption mechanism. The coordination binding of Cd(II) to MPTMS was demonstrated as an exothermic process with a high KITC value of 1.60×105 M−1 and an enthalpy value of −9.54 kJ∙mol−1. The binding reaction was mainly driven by both enthalpy and entropy, and can be completed spontaneously at any temperatures. The SOS@Cd(II)-IIPs synthesized on the SOS particle surface exhibited a maximum adsorption capacity of 41.212 mg∙g−1 for Cd(II). Meanwhile, the SOS@Cd(II)-IIPs also showed a specificity recognition ability for Cd(II) using analogues Cu(II), Pb(II), Cr(II), and Ni(II) as interference. In real samples, SOS@Cd(II)-IIPs based SPE can extract approximately 95–105% of Cd(II) with a RSD of 3.41%–8.12%, indicating that it could have wide application prospects in Cd(II) adsorption and detection.

An ultrasensitive electrochemical platform based on imprinted chitosan/gold nanoparticles/graphene nanocomposite for sensing cadmium (II) ions

An ultrasensitive electrochemical platform based on imprinted chitosan/gold nanoparticles/graphene modified glassy carbon electrode (CS/AuNPs/GR/GCE) has been used for sensing cadmium in drinking water and milk samples. The CS/AuNPs/GR/GCE platform showed high sensitivity for the determination of cadmium due to the excellent conductivity and the accelerated electron transfer by AuNPs and GR. Under the optimized conditions, the linear range of the fabricated electrode for Cd(II) ions varied from 0.1 to 0.9 μM. The detection limit of Cd(II) ions was 1.62 × 10−4 μM. In addition, the proposed platform also exhibited high selectivity, good stability, and repeatability in the determination of Cd(II) ions. Finally, the CS/AuNPs/GR/GCE platform was applied for sensing cadmium in real samples, and the results demonstrated the potential of the developed CS/AuNPs/GR/GCE as a promising electrochemical platform for quantitative analysis of Cd(II) ions in food samples.

Electrochemical sensor for determination of trace amounts of cadmium (II) in environmental water samples based on MnO2/RGO nanocomposite

ABSTRACT We describe a simple, efficient and selective method for electrochemical determination of trace quantities of cadmium (II). MnO2 nanorod was synthesised by the hydrothermal method. Graphite oxide (GO) was synthesised using the modified Hummers method and reduced to RGO. The nanocomposite with 40% RGO and 60% MnO2 (G40M60, w/w %) was made. Structure, morphology, and composition of the nanocomposite were studied using appropriate techniques. The experimental parameters affecting cadmium determination such as pH, deposition potential and deposition time were optimised using central composite design methods. Under optimum conditions, the calibration plots are linear in the 4.0 to 130 μg L−1. The detection limits (calculated for S/N ratios of 3) are 1.12 μg L−1 for Cd (II). The method was successfully applied to the determination of cadmium in environmental water samples and gave good recoveries. The student’s t-test indicated the validity and accuracy of the proposed method for the analysis of cadmium in real samples.

Comparative study for the separation, preconcentration, and determination of copper and cadmium in real samples by using two different ligands

Two new solid phase extraction methods have been developed for simultaneous separation and preconcentration of Cu(II) and Cd(II) in some food and environmental samples before their determination by flame atomic absorption spectrometry (FAAS). One of these methods is based on the absorption of the Cu(II) and Cd(II) complexes with [3-(cyanomethyl)-5-(4-methylphenyl)-4$H$-1,2,4-triazol-4-yl]carbamate (L1) and the other is based on the absorption of the Cu(II) and Cd(II) complexes with 4-(4-methylphenyl)-5-{[pyridine-4-yl-4$H$-1,2,4-triazole-3-yl)thio]methyl}-4$H$-1,2,4-triazole-3-thiol (L2) on Amberlite XAD-1180 resin. The metal complexes are retained on resin at pH 6.0 and eluted with 1.0 mol L$^{-1}$ HCl in acetone in both methods. After the optimum conditions were determined, the methods were applied to seawater, stream water, rice, lentil, tea, tobacco, bulgur, chickpea, wheat, red pepper, black pepper, peppermint, and dried eggplant samples in order to determine the levels of copper and cadmium.

Adsorption of cadmium(II) ions from aqueous solution on exfoliated graphene nanosheets and its determination by flame atomic absorption spectrometry

In this study, we investigated the enrichment ability of exfoliated graphene nanosheets for determination of trace cadmium in water and vegetable samples with flame atomic absorption spectrometry. Various experimental parameters that could affect the extraction efficiency have been investigated. Under the optimum conditions, the enrichment factor of the method for the target analyte was 100. A liner response was achieved in the concentration range of 0.3–28.8 ng mL−1. The detection limit and precision of the method were 0.2 ng mL−1 and 0.8%, respectively. The proposed method was applied to determine the cadmium in water, onion, and tomato samples and recoveries of target analyte were in the range 97.6%–98.5%. All of these experimental results indicated that this new procedure could be applied for the determination of trace cadmium in real samples.

Vortex-Assisted Ionic Liquid Microextraction Coupled to Graphite Furnace Atomic Absorption Spectrometry for Preconcentration and Determination of Trace Levels of Cadmium in Real Samples

Vortex-Assisted Ionic Liquid Microextraction Coupled to Graphite Furnace Atomic Absorption Spectrometry for Preconcentration and Determination of Trace Levels of Cadmium in Real Samples

Vortex-assisted ionic liquid microextraction coupled to flame atomic absorption spectrometry for determination of trace levels of cadmium in real samples

A simple and rapid vortex assisted ionic liquid based liquid–liquid microextraction technique (VALLME) was proposed for preconcentration of trace levels of cadmium. According to this method, the extraction solvent was dispersed into the aqueous samples by the assistance of vortex agitator. Cadmium preconcentration was mediated by chelation with the 8-hydroxyquinoline (oxine) reagent and an IL, 1-octyl-3-methylimidazolium hexafluorophosphate ([Omim][PF6]) was chosen as the extraction solvent to extract the hydrophobic complex. Several variables such as sample pH, concentration of oxine, volume of [Omim][PF6] and extraction time were investigated in details and optimum conditions were selected. Under the optimum conditions, the limit of detection (LOD) was 2.9μgL−1 for Cd (ІІ) and relative standard deviation (RSD%) for five replicate determinations of 125μgL−1 was 4.1%. The method was successfully applied to the determination of cadmium in tap water, apple and rice samples.

Sensitive determination of in , beverage and cereal samples by a novel liquid-phase microextraction coupled with flame atomic absorption spectrometry.

A new microextraction technique termed dispersive liquid-liquid microextraction based on solidification of floating organic droplet (DLLME-SFO) coupled with flame atomic absorption spectrometry (FAAS) has been developed for the determination of trace cadmium in water, beverage and cereal samples. In the DLLME-SFO, cadmium was first complexed with 8-hydroxyquinoline, and then extracted into a small volume of the extraction solvent (1-dodecanol) with methanol as a dispersive solvent. Then, the extractant was analyzed by FAAS. The main factors affecting the DLLME-SFO, such as the type and volume of the extraction solvent and dispersive solvent, extraction time, sample volume, the amount of chelating agent, and salt addition were optimized. Under the optimum conditions, the established method showed a good linearity within a range of 1-50 ng mL-1, high enhancement factor (133), low limit of detection (0.3 ng mL-1), satisfactory repeatabilities (the relative standard deviation (RSD) = 3.7%, n = 6), and high recoveries (from 91.8 to 104.4%). The method was applied to determine the cadmium in three different samples (water, beverage and cereal samples) and two certified reference materials. The results indicated that the method can be applied for the determination of trace cadmium in real samples with complex matrices.

Determination of in a sequential injection lab-on-valve system with voltammetric detection using a modified electrode.

A stripping voltammetric assay using a morin modified electrode in a sequential injection lab-on-valve system was developed for the determination of trace amounts of cadmium. The sample and reagent arrangements were achieved by a syringe pump. The target metal ions were accumulated on the morin modified glassy carbon electrode surface, and the quantification step was performed by subsequent anodic stripping voltammetry. The key experimental variables relevant to the voltammetric measurement procedure were optimized. For a 100 s preconcentration time, a linear calibration curve was obtained for a concentration range of 1 to 125 μg L-1 with a detection limit of 0.41 μg L-1. The analytical use of the established method was assessed by applying it to the determination of cadmium in real samples and carrying out recovery experiments. The method was subsequently validated by comparing the results with those given by ICP-OES.

Cadmium Selective PVC-Membranes Sensor Based on 1, 2-Bis (Quinoline-2-Carboxamido) -4-Chlorobenzene as a Neutral Carrier

The 1, 2-bis(quinoline-2-Carboxamido)-4-chlorobenzene (H2Clbqb) was used as an excellent ionophore in the construction of a cadmium(II)-selective PVC-based membrane sensor. The influences of membrane compositions on the potentiometric response of the electrodes have been found to substantially improve the performance characteristics. The best performance was obtained with a membrane composition of (H2Clbqb) (5%): PVC (31%): DBP (61%): NaTPB (3%). The sensor shows a Nernestian response for cadmium ions over a wide concentration range (1.0times106 to 1.0 times 10-1 mol.L-1) with slope of 30.3 plusmn0.4 mV decade1. The limit of detection was 8.0 times10-7 mol.L-1. It illustrates a relatively fast response time in the whole concentration range (< 10 s) and it can be used for at least 8 weeks without any divergence in potential. The electrode can be used in the pH range from 2.4 to 9.0. The selectivity coefficient of some alkali, alkaline earth, transition and heavy metal ions towards Cd2+ion have been determined. The results show proposed Cd sensor is selective over a number of mono, bi- and trivalent cations such as Pb2+, Fe3+, Ni2+, K+, and Mg2+. The analytical usefulness of the proposed electrode has been evaluated by its application in the determination of cadmium in real samples. It was successfully applied for the direct determination of Cd2+ in standard and real sample solutions.

Simultaneous Determination of Nickel and Cadmium by Adsorptive Stripping Voltammetry

AbstractA sensitive and fast method for the simultaneous determination of trace amounts of nickel and cadmium in real samples has been described using differential pulse adsorptive stripping voltammetry (DPASV) by adsorptive accumulation of the N,N′‐bis(salicylaldehydo)4‐carboxyphenylenediamine (BSCPDA)–complex on the hanging mercury drop electrode (HMDE). As supporting electrolyte 0.02 mol L−1 ammonia buffers containing ligand has been used. Optimal analytical conditions were found to be: BSCPDA concentration of 42 μM, pH 9.6 and adsorption potential at −50 mV versus Ag/AgCl. With an accumulation time of 20 s, the peaks current are proportional to the concentration of nickel and cadmium over the 1–180, and 0.5–200 ng mL−1 with detection limits of 0.06 and 0.03 ng mL−1 respectively. The sensitivity of method for determination of nickel and cadmium were obtained 0.54 and 0.98 nA mL ng−1, respectively. The procedure was applied to simultaneous determination of nickel and cadmium in some real and synthetic artificial samples with satisfactory results.

Schiff bases as cadmium(II) selective ionophores in polymeric membrane electrodes

The construction and performance characteristics of polymeric membrane electrodes based on two neutral ionophores, N, N′-[bis(pyridin-2-yl)formylidene]butane-1,4-diamine (S 1) and N-(2-pyridinylmethylene)-1,2-benzenediamine (S 2) for quantification of cadmium ions, are described. The influences of membrane compositions on the potentiometric response of the electrodes have been found to substantially improve the performance characteristics. The best performance was obtained with the electrode having a membrane composition (w/w) of (S 1) (2.15%):PVC (32.2%): o-NPOE (64.5%):KTpClPB (1.07%). The proposed electrode exhibits Nernstian response in the concentration range of 7.9 × 10 −8 to 1.0 × 10 −1 M Cd 2+ with limit of detection 5.0 × 10 −8 M, performs satisfactorily over wide pH range (2.0–8.0) with a fast response time (10 s). The sensor has been found to work satisfactorily in partially non-aqueous media up to 30% (v/v) content of methanol, ethanol and acetonitrile and could be used for a period of 2 months. The analytical usefulness of the proposed electrode has been evaluated by its application in the determination of cadmium in real samples. The practical utility of the membrane electrode has also been observed in the presence of surfactants.

Determination of lead and cadmium in samples of polv(vinyl chloride) using organic solvents by flame atomic absorption spectrometry

Flame atomization of the solutions resulting from treatment of PVC samples with organic solvents is perfectly feasible. In this work, the organic solutions resulting from treatment of PVC with organic solvents are nebulized, after dilution with acetone. This solvent is miscible with those normally used for dissolving PVC, it does not cause precipitation of the polymer and, in general, gives good performance in the flame. The method is applied to the determination of lead and cadmium in real samples of PVC, and the possible interference arising from the PVC resin and from the presence of other metals in the sample is studied.