Phase Extraction Of Trace Amounts Research Articles

Silica-coated magnetic graphene oxide nanocomposite based magnetic solid phase extraction of trace amounts of heavy metals in water samples prior to determination by inductively coupled plasma mass spectrometry

The silica-coated magnetic graphene oxide (Fe3O4-GO@SiO2) composites were synthesized by a simple procedure in this work. The nanocomposite was characterized and applied for the rapid magnetic solid-phase extraction (MSPE) of chromium (Cr), cobalt (Co), nickel (Ni), copper (Cu), cadmium (Cd), lead (Pb), silver (Ag) ions at trace level in environmental water samples. Various experimental parameters affecting the extraction efficiency of the target metal ions by Fe3O4-GO@SiO2 were investigated and optimized, including sorbent dosage, pH of sample solution, sorption time, volume and eluent concentration, as well as elution time. Under the optimal conditions, the limits of detection (LODs, 3σ) for the target analytes were obtained in the range of 2.023–13.810 ng L−1. The recoveries of the target metals in four environmental water samples ranged from 83% to 109% and the relative standard deviations (RSDs) were lower than 7%. Moreover, in batch adsorption experiments, the adsorption of these seven metal ions was relatively speedy and the equilibrium was established after shaking 35 min which kinetics followed the pseudo second-order model, indicating a chemisorption nature. The adsorption process was simulated by the Langmuir isotherm accurately, and the calculated maximum adsorption (qmax) capacities of Fe3O4-GO@SiO2 were 182.98 mg g−1, 116.35 mg g−1, 226.08 mg g−1, 149.59 mg g−1, 100.81 mg g−1, 168.55 mg g−1 and 141.09 mg g−1 for Cr (III), Co (II), Ni (II), Cu (II), Cd (II), Pb (II) and Ag (I), respectively. Finally, the developed method was successfully applied for simultaneous and sensitive determination of target metals at trace level in environmental water samples.

Synthesis of graphene oxide-based poly(p-aminophenol) composite and its application in solid phase extraction of trace amount of Ni(II) from aquatic samples

The results of investigations about the polymerization of p-aminophenol in neutral-weak alkaline medium (pH = 7-8) in our lab showed that the produced polymer which was insoluble in water and soluble in methanol has high tendency to form selectively a blue complex with Ni(II). Investigations into the chemical structure of polymer showed that polymer has a special structure, similar to polyamine in which the aromatic rings are connected through O-bridges. Based on these data, it was decided to polymerize p-aminophenol in situ on graphene oxide (GO) and use as a new sorbent for selective separation and preconcentration of trace amount of Ni(II) from water samples. By this, the rate of sorption of Ni(II) will also be increased considerably with respect to GO alone. Resulting composite (GO-Pp-AP) was characterized by FT-IR, XRD, FE-SEM, and EDS. The obtained data confirmed the uniform growth of the polymer on the GO and the absence of granular particles. The composite shows high tendency and high rate of sorption of Ni(II) and consequently was utilized for solid phase extraction (SPE) of Ni(II) ions before its determination by flame atomic absorption (FAAS). The effects of important parameters on the recovery of Ni(II) were investigated. The presence of foreign ions has no meaningful effect on the recovery percentage of Ni(II). Under the optimum conditions, limit of detection and relative standard deviation were found to be 0.70μgL-1 and 1.8% (for n = 6; at 20μgL-1 of Ni(II)), respectively. Testing the standard reference material and analyzing the spiked real samples exhibit that the procedure can be successfully employed for determination of Ni(II) in natural water and wastewater samples. Graphical abstract ᅟ.

Nanometer-sized cerium oxide particles for solid phase extraction of trace amounts of mercury in real samples prior to cold vapor atomic adsorption spectrometry

ABSTRACTCeria (CeO2) nanoparticles were synthesized using the microwave-assisted heating technique and employed as a sorbent for preconcentration of trace amounts of Hg(II) ions from aqueous solutions for the first time. The analysis of mercury was performed by cold vapor atomic absorption spectrometry (CV-AAS). The characteristics of nanoparticles were assessed using X-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques. Experimental parameters influencing the extraction procedure recovery were thoroughly investigated. Under the optimized experimental conditions, the calibration curve was linear in the range of 0.035–0.8 µg/L of mercury. The method was validated by analysis of a certified reference material.

SiO2-coated magnetic graphene oxide modified with polypyrrole–polythiophene: A novel and efficient nanocomposite for solid phase extraction of trace amounts of heavy metals

The synthesis of a novel nanocomposite comprised of SiO2-coated magnetic graphene oxide modified with a pyrrole-thiophene (mGO/SiO2@coPPy-Th) copolymer is reported in the present work. The nanocomposite was applied for the fast magnetic solid phase extraction (MSPE) of trace levels of copper, lead, chromium, zinc and cadmium from water and agricultural samples. The nanocomposite was prepared in three steps: (1) decoration of graphene oxide sheets with magnetite nanoparticles thorough a facile one-step chemical reaction strategy; (2) chemical grafting by a silica layer to obtain high stability in acidic solutions; and (3) surface modification by coPPy-Th via simultaneous oxidation polymerization of pyrrole and thiophene in the presence of mGO/SiO2 composite. The nanocomposite was subsequently characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD) and vibrating sample magnetometry (VSM) techniques. Several important experimental variables that could affect MSPE performance, including the pH of the sample, sorption time, sorbent dosage, eluent type and its concentration, eluent volume and elution time, were investigated and optimized. Under optimal conditions, the limits of detection for the target heavy metals ranged from 0.15 to 0.65μgL−1. The maximum sorption capacity of the mGO/SiO2@coPPy-Th nanocomposite was 201, 230, 125, 98 and 80mgg−1 for Cu(II), Pb(II), Zn(II), Cr(III) and Cd(II), respectively. Finally, the feasibility of the proposed method was investigated for the extraction and determination of the target metals from real matrices.

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.

Solid phase extraction of trace amounts of zinc and cadmium ions using perlite as a supper sorbent

A novel method using a packed column with perlite as a new sorbent has been developed for preconcentration of trace amounts of zinc and cadmium prior to their determination by flame atomic absorption spectrometry. Several factors that may be affected on the solid phase extraction (SPE) process, such as pH, sample volume, flow rate, volume and concentration of eluent were studied and optimized. Linearity was maintained between 0.001–0.1 µg mL −1 for zinc, and 0.001–0.3 µg mL −1 for cadmium. Detection limits based on 3S b for zinc and cadmium were 1.8 and 1.6 ng mL −1 , respectively. The relative standard deviations of eight replicate measurements of 0.02 µg mL −1 of zinc and 0.05 µg mL −1 of cadmium ions were 2.1% and 1.8%, respectively. Finally, the developed method was successfully applied to extraction and determination of the zinc and cadmium ions in the water and food samples and satisfactory results were obtained. KEY WORDS : Solid phase extraction, Zinc determination, Cadmium determination, Preconcentration, Perlite Bull. Chem. Soc. Ethiop. 2016 , 30(2), 175-184. DOI: http://dx.doi.org/10.4314/bcse.v30i2.2

Preparation of epoxidized soybean oil-grafted Fe3O4–SiO2 as a water-dispersible hydrophobic nanocomposite for solid-phase extraction of rhodamine B

In this study, epoxidized soybean oil-grafted Fe3O4-SiO2 nanocomposite (Fe3O4-SiO2-ESBO) containing a hydrophobic surface and hydrophilic polar functional groups was synthesized. The sorbent showed excellent dispersibility in aqueous solution and was utilized for magnetic solid phase extraction of trace amounts of rhodamine B in aqueous solution prior to its determination using UV–Vis spectroscopy. The sorbent was characterized by Fourier transform infrared spectroscopy, transmission electron microscopy and scanning electron microscopy. The magnetite nanoparticles had spherical shape with their grain size of <20nm. The effects of pH, sorbent mass, uptake time on the sorption of rhodamine B on Fe3O4-SiO2-ESBO were investigated using Box–Behnken design. The adsorption capacity of the sorbent was 1355μg of rhodamine B per gram of sorbent. In optimal experimental conditions, the limit of detection, limit of quantification and enrichment factor of the proposed method were 3.94μgL−1, 13.13μgL−1 and 26, respectively. The proposed method was successfully applied to the separation and determination of rhodamine B in dish washing liquid, match tips and tap water samples with recoveries in the range 96.40–98.10%.

Solid Phase Extraction of Trace Amounts of Chloramphenicol on the Silica Gel Surface Modified with Octadecyl Groups

Background. Chloramphenicol (CAP) is a broad spectrum antibiotic. It’s widely used in various fields of veterinary and can be accumulated in food of animal origin. A minimum required performance limit (MRPL) for CAP in food is significantly restricted in the EU and the USA. Most modern methods make it difficult to determine the trace amounts of the drug from various matrices without concentration. The method of liquid-liquid extraction (LLE) may be accompanied by loss of trust component. It is therefore advisable to use solid phase analyte extraction to increase the determination sensitivity by instrumental methods and CL withdrawal stability.Objective. Development of the solid phase extraction method of chloramphenicol from honey, followed by enzyme linked immunoassay.Methods. Quantitative determination of chloramphenicol was determined using enzyme linked assay (ELISA) test-kit for determination of chloramphenicol in foods, provided by LLC “XEMA”. Solid phase extraction of chloramphenicol from honey samples was studied on silica gel surface modified with octadecyl groups (SiO2-C18), “Agilent”. This method of solid phase extraction was carried out on samples of honey, that previously checked by ELISA using LLE for sample preparation.Results. Our results showed the possibility of solid phase extraction of CAP on the surface of the silica gel with oktadecyl groups. The optimal conditions for extraction the analyte on the surface of sorbent were found and the eluation condition for CAP was studied. We tested the method of solid phase extraction of CAP from honey matrics on control materials – honey samples with known concentrations of CAP, that were bought by LLC “XEMA”.Conclusions. Solid phase extraction of CAP could be used for CAP extraction form honey. The proposed method of sample preparation reduces the time of preparation for honey samples. This method is perspective for developing the method of simultaneous concentration of antibiotics from different groups followed by ELISA determination.

Impregnated multiwalled carbon nanotubes as efficient sorbent for the solid phase extraction of trace amounts of heavy metal ions in food and water samples

A new, sensitive and simple solid phase extraction (SPE), separation and preconcentration method of some heavy metal ions, Cd(II), Cu(II), Ni(II), Pb(II) and Zn(II) at trace levels using multiwalled carbon nanotubes (MWCNTs) impregnated with 2-(2-benzothiazolylazo)orcinol (BTAO) from food and water samples were investigated. The effect of analytical parameters was examined. The metals retained on the nanotubes at pH 7.0 were eluted by 5.0mL HNO3 (2.0molL−1). The influence of matrix ions on the proposed method was evaluated. The preconcentration factor was calculated and found to be 100. The detection limits (LODs) for Cd(II), Cu(II), Ni(II), Pb(II) and Zn(II) were found at 0.70, 1.2, 0.80, 2.6 and 2.2μgL−1, respectively. The relative standard deviation (RSD) and the recoveries of the standard addition method were lower than 5.0% and 95–102%, respectively. The new procedure was successfully applied to the determination of trace amounts of the studied metal ions in various food and water samples and validated using certified reference materials SRM 1570A (spinach leaves) with satisfactory and compatible results.

Electrosynthesis of a new selective chelating agent for solid phase extraction of Ni(II) from water samples: characterisation and analytical applications

A new polymer as a selective chelating agent for separation and preconcentration of nickel ions from water samples was prepared by electropolymerisation of 4-nitrophenol. Electrosynthesis was carried out on the lead cathode in aqueous sodium acetate solution. The electrode-product is a dark-brown powder, insoluble in water but soluble in methanol, N,N-dimethylformamide (DMF) and tetrahydrofuran (THF). The electrode-product was characterised by differential scanning calorimetry (DSC), gel permeation chromatography (GPC), FT-IR, 1H-NMR, cyclic voltammetry (CV) and UV-Vis spectrometry. A proper mechanism and structure of the prepared polymer was suggested. A few drops of methanolic solution of electrode-product formed a blue complex with nickel ions in an aqueous medium in the pH range of 6 to 10. This new chelating reagent was used as a coating material on activated charcoal and applied for solid phase extraction of trace amounts of nickel ions from natural and waste waters. The effect of different parameters such as type of eluent, elution conditions, sample volume and sample flow rate and mass of coating material were studied. In the presence of co-existing ions, no significant interferences were observed. Under the optimal conditions, limits of detection (LOD) and quantification (LOQ) were 0.32 and 1 µg L−1 Ni(II), respectively. The proposed method was used for determination of Ni(II) in some lagoons south of the Caspian Sea and waste waters of factories. The validity of this method was confirmed by the comparison of the obtained results with the results of ICP-OES.

Solid phase extraction of trace amount of mercury from natural waters on silver and gold nanoparticles

Silver (Ag) and gold (Au) nanoparticles impregnated in nylon membrane filters have been proposed as a new solid phase for preconcentration of mercury from natural waters. Water samples were treated with KMnO4 to convert all mercury species to inorganic Hg2+ and this was followed by the reduction of Hg2+ with NaBH4 to elemental Hg0. The determination of Hg was carried out by thermal evaporation of mercury from membrane filters using Zeeman mercury analyzer RA–915+ (Lumex, Russia). This process does not involve any additional sample treatment and sharply reduces risk of samples contamination. The limit of detection (LOD) was found to be 0.04ng (absolute mass). Relative LOD was 0.4ngL−1 for 100mL of water. The method was validated through the analysis of CRM NRCC Tort–2 (Lobster hepatopancreas) and the found value (0.30±0.07μgg−1) was in good agreement with the certified value (0.27±0.06μgg−1). High efficiency of Hg accumulation from aqueous phase to membrane filters can be attributed to a large surface area of nanoparticles.

Poly-γ-glutamic acid modified magnetic nanoparticles for fast solid phase extraction of trace amounts of Cu(ii) and Pb(ii)

In the present study, poly-γ-glutamic acid (γ-PGA) was applied to functionalize the silica-coated magnetic nanoparticles for solid-phase extraction of Cu(ii) and Pb(ii).

Solid phase extraction of trace amounts of silver, cadmium, copper, mercury, and lead in various food samples based on ethylene glycol bis-mercaptoacetate modified 3-(trimethoxysilyl)-1-propanethiol coated Fe3O4 nanoparticles

Extraction, pre-concentration, and determination of trace amounts of silver, cadmium, copper, mercury, and lead from some food samples were investigated by magnetic solid phase extraction using Fe3O4 nanoparticles coated with 3-(trimethoxysilyl)-1-propanethiol and modified with ethylene glycol bis-mercaptoacetate as a new adsorbent. SEM, X-ray diffraction, and FT-IR were used to characterise the adsorbent. Metal ions were measured using ICP-OES, except for mercury, which was determined by CV-AAS method. Various factors affecting the extraction and desorption of target metal ions were investigated. 1mL of 1mol/L HCl and 5% thiourea was used as eluent. The detection limits of 0.07, 0.06, 0.09, 0.01, and 0.08ng/mL were obtained for silver, cadmium, copper, mercury, and lead with enrichment factors of 240, 294, 297, 291, and 236, respectively. The method was used for determination of target metal ions in rice, canned tuna fish, and tea leaves.

Solid phase extraction of trace amount of Cu(II) using functionalized-graphene

A novel and selective method for the fast determination of trace amounts of Cu(II) ions in water samples has been developed. The first organic-solution-processable functionalized-graphene (SPF-Graphene) hybrid material with porphyrins, porphyrin-graphene nanohybrid, 5-(4-aminophenyl)-10, 15, 20-triphenyl porphyrin and its photophysical properties including optical (TPP) and grapheme oxide molecules covalently bonded together via an amide bond (TPP-NHCO-SPFGraphene) were used as absorbent for extraction of Cu(II) ions by solid phase extraction method. The complexes were eluted with HNO3 (2 M) 10% (vol/vol) methanol in acetone and determined the analyte by flame atomic absorption spectrometry. The procedure is based on the selective formation of Cu(II) at optimum pH by elution with organic eluents and determination by flame atomic absorption spectrometry. The method is based on complex formation on the surface of the ENVI-18 DISK™ disks modified porphyrin-graphene nanohybrid, 5-(4-aminophenyl)-10,15,20-triphenyl porphyrin (TPP) and grapheme oxide molecules covalently bonded together via an amide bond (TPP-NHCO-SPFGraphene) followed by stripping of the retained species by minimum amounts of appropriate organic solvents. The elution is efficient and quantitative. The effect of potential interfering ions, pH, TPP-NHCO-SPFGraphene, amount, stripping solvent, and sample flow rate were also investigated. Under the optimal experimental conditions, the break-through volume was found to about 1000 mL providing a preconcentration factor of 600. The maximum capacity of the disks was found to be 398 ± 3 μg for Cu2+. The limit of detection of the proposed method is 5 ng per 1000 mL. The method was applied to the extraction and recovery of copper in different water samples.

Solid phase extraction of trace amounts of palladium in environmental water samples on multi-walled carbon nanotubes as a new sorbent: comparison with activated carbon

AbstractA solid phase extraction procedure is proposed for the separation and preconcentration trace amounts of Pd (II) in aqueous medium by using a column of multi-walled carbon nanotubes (MWCNTs) modified with 1-(2-pyridylazo)-2-naphtol (PAN). The elution was carried out with 5.0 mL of 2 mol L−1 thiourea in 4 mol L−1 HCl. The amount of eluted Pd (II) was measured using flame atomic absorption spectrometry. The influences of the various experimental parameters, including pH, eluent type, concentration of eluent, amount of sorbent, and interfering ions on the recovery of palladium ions were investigated. The detection limit for palladium under the optimum condition was 1.0 ng mL−1 with enrichment factor of 100 and the relative standard deviation was 1.89% (n = 6, C = 0.5 μg mL−1). The method was applied for the determination of Pd (II) in water samples. The enrichment performance of the method using modified MWCNTs as preconcentration sorbent was also compared with PAN-modified activated carbon.

Solid phase extraction of trace amounts of silver (I) using dithizone-immobilized alumina-coated magnetite nanoparticles prior to determination by flame atomic absorption spectrometry

A new, simple, fast and reliable solid-phase extraction (SPE) method has been developed to separation/preconcentration of trace amounts of silver ion from environmental water samples using dithizone/sodium dodecyl sulfate immobilized on alumina-coated magnetite nanoparticles (DTZ/SDS-ACMNPs) and its determination by flame atomic absorption spectrometry. The coating of alumina on Fe3O4 NPs not only avoids the dissolving of Fe3O4 NPs in acidic solution, but also extends their application without sacrificing their unique magnetization characteristics. This method avoided the time-consuming column-passing process of loading large volume samples in traditional SPE through the rapid isolation of DTZ/SDS-ACMNPs with an adscititious magnet. Optimal experimental conditions including amount of DTZ/SDS, pH value, standing time, sample volume, type, volume and concentration of eluent and co-existing ions have been studied and established. Under the optimal experimental conditions, the detection limit for Ag(I) with enrichment factors of 100 was found to be 0.52 ng mL−1 and its relative standard deviations (RSD) was 3.4% (n = 10, C = 5.0 µg mL−1). The linear range of calibration curve for Ag(I) was 2–5000 ng mL−1 with a correlation coefficient of 0.9991. The proposed method was successfully applied to the determination of target analyte in different water and wastewater samples. The validity of the method has been checked by applying it to study the recovery of silver ion in spiked water and wastewater samples.

Nanobeads-based rapid magnetic solid phase extraction of trace amounts of leuco-malachite green in Chinese major carps

A proof-of-concept for the use of oleic acid coated magnetic nanobeads (OA-MNBs) for the magnetic solid phase extraction (MSPE) of trace amounts of leuco-malachite green (LMG) from fish samples was developed. The OA-MNBs were prepared by covalently conjugating oleic acid on amino-modified magnetic polystyrene beads. The OA-MNBs were characterized with transmission electron microscopy, Fourier transform infrared spectroscopy and zeta-potential analyzer. The optimized parameters for MSPE with OA-MNBs of LMG from fish muscle involved a combination of pH 10.0 in 10% acetonitrile, 1.5M sodium chloride as an adsorption solution, and an extraction procedure involving 6mg OA-MNBs in 18mL LMG adsorption solution. This was optimized for 0.5g fish muscles with an incubation period of 10min using 200μL acetonitrile for elution. Using the optimized parameters, the performance of MSPE with OA-MNBs was evaluated by analyzing LMG-spiked fish extracts with liquid chromatography-mass spectrometry (LC-MS/MS) method. The results indicated that recoveries of LMG (from 0.1 to 2ng/g) ranged from 71.2%–112.6% with relative standard deviations as low as 0.6%. Out of 57 field fish samples, eight LMG positive samples were confirmed using MSPE with OA-MNBs. Compared with traditional liquid–liquid extraction methods, the results showed that MSPE with OA-MNBs had a higher sensitivity for samples with low LMG concentration. Furthermore, the MSPE with OA-MNB took only 40min to perform without the need for time consuming sample-pretreatment process. Therefore, MSPE with OA-MNBs holds promise for rapid, sensitive, and cost effective screening for LMG in fish samples.

Light-induced pH change and its application to solid phase extraction of trace heavy metals by high-magnetization Fe3O4@SiO2@TiO2 nanoparticles followed by inductively coupled plasma mass spectrometry detection

We report here the preparation of high-magnetization Fe3O4@SiO2@TiO2 nanoparticles for solid phase extraction of trace amounts of Cd(II), Cr(III), Mn(II) and Cu(II) from environmental waters. The prepared nanoparticles were characterized by scanning electron micrograph (SEM) and transmission electron microscopy (TEM). The high-magnetization nanoparticles carrying the target metals could be easily and fast separated from the aqueous solution simply by applying an external magnetic field while no filtration or centrifugation was necessary. A light-induced hydroxide ion emitter, molecular malachite green carbinol base (MGCB) was applied to adjust pH value of solution for quantitative adsorption instead of the conventional used buffer. In the presence of UV light, MGCB gives out OH− ions, and this leads to an increase in the pH value without the aid of buffer solution. Using high-magnetization Fe3O4@SiO2@TiO2 nanoparticles as the extraction material and the light-induced MGCB for pH adjustment, we developed an efficient and convenient two-step method for separation/preconcentration trace amounts of Cd(II), Cr(III), Mn(II) and Cu(II) in environmental water samples followed by inductively coupled plasma mass spectrometry (ICP-MS) detection. The parameters affecting the extraction such as MGCB concentration, exposal time, sample volume, eluent condition, and interfering ions have been investigated in detail. Under the optimized conditions, the limits of detection for Cd(II), Cr(III), Mn(II) and Cu(II) were 4.0, 2.6, 1.6 and 2.3ngL−1, respectively, and the relative standard deviations (RSDs, c=1μgL−1, n=7) were 3.6%, 4.5%, 4.0 and 4.1%, respectively. The proposed method has been validated using certified reference materials, and it has been successfully applied in the determination of trace Cd(II), Cr(III), Mn(II) and Cu(II) in environmental water samples.

Solid Phase Extraction of Trace Amounts of Cadmium with Cetyltrimethylammonium Bromide‐Coated Magnetic Nanoparticles Prior to Its Determination by Flame Atomic Absorption Spectrometry

AbstractA solid‐phase extraction (SPE) method has been presented for the selective separation and preconcentration of trace amounts of cadmium using cetyltrimethylammonium bromide (CTAB)‐coated Fe3O4 nanoparticles (NPs). The method is based on the sorption of cadmium as CdI42− complex on the positively charged surface of the CTAB‐coated Fe3O4 NPs. The preconcentrated cadmium is then desorbed from the surface of the sorbent and is determined by flame atomic absorption spectrometry. The influences of the experimental parameters including pH of the solutions, amount of surfactant, iodide concentration, sample volume, eluent type and volume on the recovery of the analyte ions were investigated. Under the optimum conditions by the extraction of 500 mL of aqueous samples, a preconcentration factor of 250 was achieved. The detection limit (3s) was 0.06 μg L−1, and the relative standard deviations at 0.5 and 5 μg L−1 levels of cadmium (n = 10) were 3.2 and 1.9% respectively. The proposed method was successfully applied to the determination of cadmium in water samples. The accuracy was evaluated through the recovery experiments and independent analysis by the graphite furnace atomic absorption spectrometry (GFAAS).

Solid phase extraction of trace amounts of palladium ions using multiwalled carbon nanotube modified by N,N’-bis(2-hydroxy-benzylidene)-2,2’(aminophenylthio) ethane prior to determination by flame atomic absorption spectrometry

Multiwalled carbon nanotubes modified with N,N&rsquo;-bis(2-hydroxybenzylidene)-2,2&rsquo;(aminophenylthio) ethane have been developed for the selective separation and/or preconcentration of trace amounts of Pd(II) in aqueous medium. Parameters including pH of aqueous solution, flow rates, the amount of ligand and the type of stripping solvents were optimized. It was found that the sorption is quantitative in the pH range (1.5-4), whereas quantitative desorption occurs instantaneously with 3.0 mL of 0.3 M Na2SO3. Linearity was maintained between 0.01 to 22 mg mL-1 for Pd in the final solution. The breakthrough volume was greater than 1800 mL with an enrichment factor of more than 600 and 6.0 mg L&minus;1 detection limit (3s, n = 10). The effects of various ions interferences on the percent recovery of palladium ion were studied. The method was successfully applied to the determination of palladium ion in environmental samples.&nbsp;KEY WORDS: Multiwalled carbon nanotubes, Preconcentration, Palladium(II) determinationBull. Chem. Soc. Ethiop. 2012, 26(1), 19-26.DOI: http://dx.doi.org/10.4314/bcse.v26i1.3