Preconcentration Of Cadmium Research Articles

A switchable ionic liquid with polarity swing‐assisted regeneration properties used for the preconcentration of cadmium in biological samples

In the present study the cadmium (Cd) was determined in serum samples of psoriatic patients. The severity of psoriasis was evaluated according to criteria based on standard clinical diagnosis using Psoriasis Area Severity Index (PASI) score. In present study, an innovative tunable green solvent system based microextraction (TSS‐ME) was applied for the enrichment of Cd in acid digested serum samples prior to determination with flame atomic absorption spectrometry. The hydrophobic complex of Cd‐ammonium pyrrolidine thiocarbamate was extracted in a tunable solvent system which was prepared from a polybasic amine (N, N, N′, N′‐tetramethyl‐1, 4‐diaminobutane), decanol and water system. The tunable green solvent system (TSS) which has zero ionic strength was converted to homogeneous monophasic polar hydrophilic phase via exposure to CO2 at different pressure and time duration. Then hydrophobic enriched Cd‐ ammonium pyrrolidine thiocarbamate was back extracted, using HNO3 (0.1 to 0.5 mol L−1) then the second round of TSS‐ME was applied. The acidic aqueous phase enrich with analyte was separated from tunable solvent. The separated TSS was easily reused for up to 10 time for preconcentration purposes without loss of its enrichment character. The smoker and nonsmoker psoriatic patients at PASI >10, have two to three folds higher Cd levels in serum samples than healthy persons.

An environment-Friendly Cloud Point Extraction Method for preconcentration and determination of Lead and Cadmium in Water Samples

A new, cost-effective, and environmental-friendly cloud point extraction methodology was described for enrichment of lead and cadmium in real water samples. The method involves the complexation of lead or cadmium with 2-nitro-6-(1,3-thiazol-2-diazeyl)-phenol at pH 8.5 and 7.0 for cadmium and lead, respectively, then extraction into Triton X-114. After dilution of the surfactant-rich phase with acidified methanol, the enriched analytes concentration was estimated by spectrophtotmetric measurements at 590 and 540, respectively. Parameters that influenced cloud point extraction, such as pH, reagent, surfactant and nitric acid concentrations, centrifuge rate and time, temperature, incubation time, as well as interferences were evaluated and optimized. The preconcentration factor was 50 and the detection limits were 1.64 and 1.62 µg L-1 for lead and cadmium, respectively. The method presented relative standard deviation as precision were 2.28% and 1.96% for lead and cadmium, respectively. The accuracy of the new preconcentration procedure was checked by the analysis of the standard reference materials, and successfully applied to determine lead and cadmium in real water samples with relative recovery values in the range of 95.40%–101% for the spiked samples.

Comparison of Methods for the Preconcentration of Cadmium (II) Using Amberlite XAD-16 Resin Modified with Anoxybacillus caldiproteolyticus and Geobacillus stearothermophilus as Novel Biosorbents

The isolation, identification and characterization of bacteria obtained from soil of Ergani Makam Mountain were performed and the results revealed that the bacteria were thermophilic Anoxybacillus caldiproteolyticus. The characterized bacteria and purchased Geobacillus stearothermophilus were immobilized on Amberlite XAD-16 in order to prepare two biosorbents for preconcentration experiments for the determination of cadmium (II) ions. The produced biosorbents were enriched separately using mini-columns and the analyte was determined by flame atomic absorption spectrometry. The effects of solution parameters were investigated for the separation and preconcentration yields. The recovery efficiencies of Amberlite XAD-16 immobilized separately with A. caldiproteolyticus and G. stearothermophilus were determined to be 98.23 ± 2.40 and 98.93 ± 1.3 (n = 5) for the optimum working conditions, respectively. Moreover, the Cd (II) ion was recovered with 10 mL of 1 mol L−1 of HCl and 2 mL of 0.5 mol L−1 HNO3 solutions. The optimum working conditions were determined to be at pH 6.0 and a flow rate of 2 mL min−1 for both biosorbents. The recovery efficiencies of matrix ions were characterized to investigate the feasibility of the developed preconcentration methods. The accuracy of the proposed methods were controlled by analyzing a SCP Science EnviroMAT Waste Water, Low (EU-L-2) certified reference material. The obtained results were comparable to the certified values. These methods were also applied to the analysis of water samples from Dicle River, Hazar Lake and Diyarbakır tap water for Cd (II).

Determination of cadmium at trace levels in parsley samples by slotted quartz tube-flame atomic absorption spectrometry after preconcentration with cloud point extraction

In this study, a cloud point extraction (CPE) method for the extraction and preconcentration of cadmium was developed with its determination by slotted quartz tube-flame atomic absorption spectrometry (SQT-FAAS). Method developed is based on the reaction of cadmium with diphenylcarbazone to form a coordinated hydrophobic ion-associated complex, and subsequent extraction into the surfactant-rich phase of extraction solvent. The main factors affecting the analyte recovery such as volume of surfactant and concentration, equilibrium temperature, eluent type and volume were investigated to obtain optimum extraction conditions.Under the optimum conditions, detection and quantification limits were found to be 0.70 and 2.3 ng mL−1, respectively. About 60 folds enhancement in detection power for the analyte was recorded over the FAAS instrument. The accuracy and applicability of the method was performed by spiking parsley samples at different concentrations, and the %recovery results were found to be between 93 and 105%.

A monolithic copolymer prepared from N-(4-vinyl)-benzyl iminodiacetic acid, divinylbenzene and N,N′-methylene bisacrylamide for preconcentration of cadmium(II) and cobalt(II) from biological samples prior to their determination by ICP-MS

A capillary monolith consisting of poly[N-(4-vinyl)-benzyl iminodiacetic acid-co-divinylbenzene-co-N,N'-methylene bisacrylamide), referred to as poly(VBIDA-DVB-Bis), has been prepared. It is shown to be an efficient sorbent for the enrichment of Co(II) and Cd(II). The two ions are completely retained by the monolith in the pH range from 4.0 to 9.0. The breakthrough curve tests were adopted to evaluate the adsorption performance of the monolith towards Co(II) and Cd(II). A dose-response model was used to describe the breakthrough curves of the two ions at different initial concentrations. The adsorption capacities for Co(II) and Cd(II) are 1.54 and 1.73mg·m-1 at a concentration level of 2.5mg·L-1, respectively. The enrichment factor is 100, and the required sample volume is 5mL. Following elution of the two ions with 0.5M HNO3, they were quantified by ICP-MS. The limits of detection in a 1mL sample are 0.35ng·L-1 for Co(II) and 0.44ng·L-1 for Cd(II). The method was applied to the determination of Co(II) and Cd(II) in spiked rice, human urine and seawater samples. Graphical abstract Schematic representation of a monolithic copolymer prepared from N-(4-vinyl)-benzyl iminodiacetic acid (VBIDA), divinylbenzene (DVB) and N,N'-methylene bisacrylamide (Bis) and its application for selective capturing of cadmium(II) and cobalt(II) from complex sample matrices prior to their determination by ICP-MS.

Magnetic Mn2O3 nanocomposite covered with N,N'-bis(salicylidene)ethylenediamine for selective preconcentration of cadmium(II) prior to its quantification by FAAS.

This article describes a method for highly selective preconcentration of Cd(II) via magnetic Mn2O3 coated by N,N'-bis(salicylidene)ethylenediamine (BSED). The metal oxide components were prepared via combining sol-gel and precipitation methods. Then, BSED was added as the third component of the composite. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, alternating gradient force magnetometry, and Fourier transform infrared spectroscopy were applied to characterize the materials. BSED selectively forms a complex with Cd(II), and the sorbent can then be magnetically separated. The preconcentration conditions were optimized as pH value (4.0 ± 0.5), sorbent amount (30mg), adsorption time (20min), eluent 2 MHNO3), eluent volume (1.5mL) and desorption time (4min). The quantification of Cd(II) was done by flame atomic absorption spectroscopy. Themethod has the following figures of merit: (a) a detection limit of 320µgL-1, (b) a relative standard deviation of 1.1%, (c) an enhancement factor of 36, (d) a preconcentration factor of 33, and (e) a linear dynamic range that extends from 10 to 120μgL-1. Other features include the use of safe reagents, fast and simple preparation, high selectivity and reliable analytical performance. The effects of potentially interfering ions were examined. The Dubinin-Radushkevich model and the pseudo second-order model are found to fit the adsorption behavior. The absorption is spontaneous and exothermic. The method was successfully applied to the determination of Cd(II) in (spiked) fruit samples. Graphical abstract Schematic presentation of a nanocomposite (Fe3O4 - Mn2O3 - Schiff base) that was prepared from MnCl2, H2O2, FeCl2, FeCl3, NH3, salicylaldehyde, ethylenediamine and tetraethylammonium hydroxide for the magnetic solid phase extraction of cadmium at trace levels.

Phthalic acid as complexing agent and co-disperser for analysis of zinc and cadmium at trace levels from high volumes of sample on the base of an effervescence-assisted dispersive liquid-liquid microextraction

A green effervescence-assisted dispersive liquid-liquid microextraction based on phthalic acid as complexing agent and co-disperser performed in a narrow-bore tube has been developed for the extraction and preconcentration of zinc and cadmium from high volume of aqueous sample, followed by flame atomic absorption spectrometry. Initially phthalic acid is added to the aqueous sample to form phthalate-metal complexes. Then the sample is transferred by a syringe into a home-made setup consists of a narrow-bore glass tube with its nozzle-shaped head when its bottom connected to a glass balloon containing sodium bicarbonate and an extraction solvent at μL-level. Immediately a reaction occurs between the sodium bicarbonate and the excess amount of phthalic acid, and the produced CO2 leads to the dispersion of the extractant into the sample as fine droplets which result in extraction of the complexes into the extractant. Under the optimum conditions, the calibration curves were linear in the ranges of 0.50–7.5 and 0.30–7.5 μg L−1 for cadmium and zinc, respectively. The detection limits were 0.21 and 0.14 μg L−1 for cadmium and zinc, respectively. Extraction recoveries were 89% and 100%, and enrichment factors were found to be 117 and 131, for cadmium and zinc, respectively. Finally environmental water and fruit juice samples were successfully analyzed using the developed method.

A highly selective magnetic solid-phase extraction method for preconcentration of Cd(II) using N,N′-bis(salicylidene)ethylenediamine in water and food samples

In this work, a highly selective method is presented for the preconcentration of cadmium. The developed magnetic solid-phase extraction is based on the adsorption of Cd(II)-N,N′-bis(salicylidene)ethylenediamine (BSE) complex on Fe3O4-embedded graphene oxide nanocomposite. The N,N′-bis(salicylidene)ethylenediamine ligand was used prior to extraction in order to increase the selectivity of the Cd(II) extraction process. Cd(II) concentrations were determined by flame atomic absorption spectroscopy. The π–π interaction between the Cd(II) and BSE complex and graphene oxide results in selective adsorption of the Cd complex compared to complexes of BSE with other heavy metal ions. The central composite design technique was performed to optimize the effective chemical parameters, including pH, amount of adsorbent, and ligand concentration. Under the optimum conditions, the method showed a linear concentration range of 1.0–130.0 ppb, limit of detection of 0.4 ppb with the relative standard deviation of 3.9% for blank solutions (n = 8), and a preconcentration factor of 50 for determination of Cd(II). The kinetics, thermodynamics, and isotherm of the adsorption process were also studied. The proposed method was successfully applied to water and vegetables samples.

Simultaneous Voltammetric Determination of Cd2+, Pb2+, and Hg2+ Ions Using Aminosepiolite-Coated Glassy Carbon Electrode: Optimization of Detection Parameters via Response Surface Methodology

Adsorptive stripping voltammetry using a glassy carbon electrode modified by a film of aminosepiolite was utilized for simultaneous pre-concentration and trace detection of cadmium, lead, and mercury ions in aqueous solution. The modified sepiolite exploited as electrode material was obtained by grafting on its surface of [(3-(2-aminoethylamino)propyl)]trimethoxysilane (AEPTMS). The results demonstrated that the amine groups on sepiolite efficiently affected the voltammetric detection of heavy metals. The full factorial design matrix and response surface methodology were applied in designing experiments, to determine the optimal conditions and to evaluate their mutual interactions. The high values of adjusted R2 obtained of the fitted model show that the experiments data were well explained by the model, which then allowed to acquire optimum parameters for the electroanalysis and detection of the analytes by differential pulse voltammetry. At pH 6.5 of accumulating medium, with an electrolysis potential of –0.9 V and in the concentration range of 10−8 M to 10−9 M, calibration plots were obtained. The limits of detection (3Sd/m) were 8.689 × 10−10 M, 8.197 × 10−10 M, and 8.099 × 10−10 M, respectively, for Cd2+, Pb2+, and Hg2+ ions. The interference effect of several cations and anions on the response of the analytes was also evaluated, and finally, the sensor was applied to the simultaneous detection of metal ions in tap water with satisfactory recovery rates.

Development of a new method for extraction and preconcentration of cadmium and zinc ions in edible oils based on heat-induced homogeneous liquid–liquid microextraction

A new sample preparation method, cyclohexylamine-based heat-induced homogeneous liquid–liquid microextraction, has been developed for the extraction and preconcentration of Cd(II) and Zn(II) ions in edible oils followed by flame atomic absorption spectrometry determination. First, the analytes are extracted into an acidic solution (a balanced mixture of HNO3 and HCl). Second, they are preconcentrated via the microextraction method. Accordingly, cyclohexylamine (as a complexing agent and an extraction solvent) is added at µL-level into the obtained solution containing the analytes to form a homogeneous solution followed by the addition of sodium chloride. After manual shaking, the obtained solution is placed in a water bath thermostated at 60 °C. A cloudy solution because of the decrease in cyclohexylamine solubility in water at high temperature is formed. After centrifuging fine droplets of cyclohexylamine containing Cd(II) and Zn(II)—cyclohexylamine complexes are collected on the top of the aqueous phase. The preconcentrated analytes in the upper phase by use of flame atomic absorption spectrometry are analyzed and determined. Several variables possibly affecting the extraction efficiency were investigated and optimized. Under the optimum conditions, the calibration curves were linear in the ranges of 10–300 and 2.5–200 µg kg− 1 for Cd(II) and Zn(II), respectively. Repeatability of the proposed method, expressed as relative standard deviation, was obtained 2.4 and 1.7% for Cd (II) and Zn(II), respectively. Moreover, the detection limits of the selected analytes were obtained 3.8 and 0.6 µg kg− 1 for Cd(II) and Zn(II), respectively.

Optimization of magnetic solid phase microextraction with CoFe2O4 nanoparticles unmodified for preconcentration of cadmium in environmental samples by flame atomic absorption spectrometry

A method of preconcentration based in the magnetic solid phase microextraction with CoFe2O4 nanoparticles for the determination of cadmium in oyster and water samples using flame atomic absorption spectrometry (FAAS). Magnetic nanomaterials ones have aroused a greater interest in the area of analytical chemistry because of the high area of material and separation facility of the adsorbent. The statistical significance variables, extraction time, nanoparticles mass, pH, eluent concentration and desorption time were evaluated using a fractional factorial design of two levels (25–1). Afterward, a design Doehlert was used to optimize the pre-concentration process. The best experimental conditions were: nanoparticles mass (25 mg), pH (10.0) and eluent concentration of 1.20 mol L−1. The method allowed the determination of cadmium with a LOD of 0.24 μg L−1 and LOQ of 0.80 μg L−1. The precision expressed as relative standard deviation (RSD) of 3.33% for cadmium concentration with 20 μg L−1, the accuracy of the method was confirmed by the analysis of materials certified reference NIST 1566b Oyster tissue, pre-concentration factor 31. The method was applied to the analysis of the oyster and water samples has determined the concentration of cadmium from 4.6 to 7.8 mg kg−1 for oyster and 2.75 to 4.8 μg L−1 for water.

Undecanol-ethanol-water ternary system based microextraction for the detection of cadmium

An eco-friendly, simple, and sensitive solidification of floating organic drop based dispersive liquid?liquid microextraction (SFODME) procedure was introduced for the separation and preconcentration of cadmium. After 2-(5-bromo- -2-pyridylazo)-5-(diethylamino)phenol (5-Br-PADAP) was complexed with cadmium ions in sample, the undecanol?ethanol?water ternary system was used as an organic solvent for extraction. The main factors relevant to the microextraction efficiency such as pH, concentration of 5-Br-PADAP, amount of extraction solvent were optimized. The detection limit is 0.01 ?g L-1 along with preconcentration factor 266. The recovery of the analyte was between 98 % and 103 %, with relative standard deviation below 6 %. The developed procedure was successfully tested on the analysis of water, hair dye, and food samples.

Application of vortex-assisted solid-phase extraction for the simultaneous preconcentration of Cd(ii) and Pb(ii) by nano clinoptilolite modified with 5(p-dimethylaminobenzylidene) rhodanine

Herein, a simple, fast and reliable method based on vortex-assisted solid-phase extraction (VA-SPE) followed by flame atomic absorption spectrometry was developed for the simultaneous preconcentration and trace detection of cadmium and lead.

Harmless Disposal and Comprehensive Recovery of Cadmium Waste Slag

According to the material characteristics of cadmium waste slag, it obtained oxide dust which were the preconcentration of cadmium and other metal by roasting, The best process parameters also was obtained through the test. Detoxicated slag was processed by grinding and magnetic separation. The iron grade of rich iron slag was 56.27% and the iron grade of the poor iron slag was 30.7%.

Micro-organic Ion-associate Phase Extraction/micro-volume Back-extraction for the Preconcentration and GF-AAS Determination of Cadmium, Nickel and Lead in Environmental Water.

Micro-organic ion-associate phase (IAP) extraction was combined with a micro-volume back-extraction (MVBE) to reduce coexisting components and viscosity in the concentrates. Heavy metals were converted into a complex with 2-(5-bromo-2-pyridylazo)-5-(N-propyl-N-sulfopropylamino)phenol in a 40-mL sample solution, and were extracted into ion associates. After centrifugation and discarding the aqueous phase, trace metals were stripped from IAP into a nitric acid solution, followed by GF-AAS determination. Only one vessel was required for 400-fold enrichment. The detection limits (3σb) for Cd, Ni, and Pb were 0.6, 3.7, and 0.8 ng/L, respectively. This method was applied in recovery tests in seawater.

Solid-phase extraction method for preconcentration of cadmium and lead in environmental samples using multiwalled carbon nanotubes

A new sensitive and accurate solid-phase extraction method for preconcentration of trace amounts of cadmium and lead in various environmental samples prior to flame atomic absorption spectrometry determination has been developed. The proposed method is based on the utilization of multiwalled carbon nanotubes in combination with 5-benzyl-4-[-chlororbenzylidene amine]-4H-1,2,4-triazole-3-thiol (BCBATT) as a solid-phase sorbent with the aid of ultrasonication. The effect of the preconcentration parameters was investigated. Good recoveries ranging from 95% to 102% with relative standard deviations of 3.2% and 2.8% for Cd$^{2+}$ and Pb$^{2+}$, respectively, were obtained, indicating high accuracy and precision. The limits of detection were 0.2 and 0.5 $\mu $g/L for Cd$^{2+}$ and Pb$^{2+}$, respectively. The preconcentration factor was 100. The validation of the proposed preconcentration procedure was performed using certified reference materials with satisfactory and compatible results. The proposed method was applied to various real environmental samples for determination of Cd$^{2+}$ and Pb$^{2+}$ concentrations and satisfactory results were obtained.

Vortex-assisted switchable liquid-liquid microextraction for the preconcentration of cadmium in environmental samples prior to its determination with flame atomic absorption spectrometry.

In this study, a switchable solvent was used to preconcentrate trace amounts of Cd from aqueous solution for its determination by flame atomic absorption spectrometry (FAAS). Protonation of N,N-dimethylbenzylamine by dry ice (solid CO2) made it water soluble, and addition of sodium hydroxide converted it back to its original nonionic state for phase separation and subsequent extraction of Cd. A slotted quartz tube (SQT) was attached to the flame burner head to increase the residence time of Cd atoms in the light path. Under the optimum conditions, limits of detection and quantification were determined as 0.7 and 2.6μgL-1, respectively. Low relative standard deviations calculated from seven replicate measurements of the lowest concentration indicated high precision. Accuracy of the developed method was checked by using a standard reference material (SRM 1633c). Spiked recovery tests were also performed on lake water and wastewater samples at different concentrations to check the applicability of the developed method, and the results obtained (90-103%) established high recovery.

Synthesis of amberlite XAD-2-ANSA resin for separation, preconcentration and spectrophotometric determination of trace elements in food samples

A new chelating sorbent has been synthesized using Amberlite XAD-2 resin functionalized with 1-amino-2-naphthol-4-sulfonic acid (ANSA) through –N=N– group. This sorbent, characterized by infrared (FTIR) spectra and optimized for sorption-desorption of the studied metal ions then, it was used as packing for the column for separation/ preconcentration of cadmium, cobalt, and nickel prior to their determination spectrophotometrically. Metal ions of Cd, Ni, and Co sorbed in the column were eluted one by one with 0.02 M, 0.10 M, and 0.20 M HCl acid respectively. Under the optimal conditions, the proposed procedure enabled the determination of Cd, Co, and Ni with detection limits of 0.98, 0.30 and 2.10 μg L− 1 respectively. The developed procedure was evaluated by the analysis of mixed metal ions Cd, Co and Ni solution contained 0.30, 30, and 1.25 µg respectively, and the percentage recovery was 95.5 – 104%. The procedure was applied to the analysis of food samples (grains of Sorghum bicolor), and the results obtained were compared with that of FAAS (before and after separation/preconcentration).

Nafion coated flexible bismuth sensor for trace lead and cadmium determination

This paper reports a low-cost and highly sensitive flexible sensor for the determination of lead and cadmium in tap and lake water. This sensor achieved low detection limits and high performance by decorating cation-exchanging resin and in situ deposited bismuth on the working electrode. In situ deposited bismuth film was much easier to fabricate and formed a highly porous 3-dimensional structure, which provided more surface area for the reaction of the target ions. The cation-exchanging Nafion film can help reduce the interference caused by surface active compounds and enhance the pre-concentration of lead and cadmium at the same time. Flexible polypropylene film was chosen as the substrate to reduce the cost and expand the sensor's applications. Finally, the detection limits were 1.68 ppb for Pb and 1.24 ppb for Cd at the deposition time of 300 s. Particularly, this sensor revealed good linearity (R2ý=ý0.993) at a wide range of 10---500 ppb for cadmium in tap water environment. The proposed sensor was successfully applied to lead and cadmium determination in environmental water samples and the results were in good agreement with those from a standard procedure.

Ultrasound-assisted surfactant-enhanced emulsification microextraction using a magnetic ionic liquid coupled with micro-solid phase extraction for the determination of cadmium and lead in edible vegetable oils

A novel ultrasound-assisted surfactant-enhanced emulsification microextraction (UASEME) using a magnetic ionic liquid (MIL) coupled with micro-solid phase extraction was developed for the preconcentration of cadmium and lead in edible vegetable oils prior to analysis by graphite furnace atomic absorption spectrometry. MIL [C4mim] [FeCl4] was used as the extractant, non-ionic surfactant Triton X-100 as the emulsifier and Fe3O4 nanoparticles as the sorbent, while ultrasound was applied to assist the dispersion of the extractant and accelerate the mass transfer process. By mixing Fe3O4 nanoparticles with the MIL after UASEME, the phase separation time was shortened and the separation can be simplified by applying an external magnetic field. Under the optimized conditions, the proposed method was validated and the results demonstrated that the method can produce satisfactory linearity, sensitivity, reproducibility and recovery for the analytes. Finally, the method was successfully applied for the determination of Cd and Pb in edible vegetable oil samples.