Solid-phase Extraction Of Metal Ions Research Articles

4D-Printed Elution-Peak-Guided Dual-Responsive Monolithic Packing for the Solid-Phase Extraction of Metal Ions.

Four-dimensional printing (4DP) technologies are revolutionizing the fabrication of stimuli-responsive devices. To advance the analytical performance of conventional solid-phase extraction (SPE) devices using 4DP technology, in this study, we employed N-isopropylacrylamide (NIPAM)-incorporated photocurable resins and digital light processing three-dimensional printing to fabricate an SPE column with a [H+]/temperature dual-responsive monolithic packing stacked as interlacing cuboids to extract Mn, Co, Ni, Cu, Zn, Cd, and Pb ions. When these metal ions were eluted using 0.5% HNO3 solution as the eluent at a temperature below the lower critical solution temperature of polyNIPAM, the monolithic packing swelled owing to its hydrophilic/hydrophobic transition and electrostatic repulsion among the protonated units of polyNIPAM. These effects resulted in smaller interstitial volumes among these interlacing cuboids and improvements in the elution peak profiles of the metal ions, which, in turn, demonstrated the reduced method detection limits (MDLs; range, 0.2-7.2 ng L-1) during analysis using inductively coupled plasma mass spectrometry. We studied the effects of optimizing the elution peak profiles of the metal ions on the analytical performance of this method and validated its reliability and applicability by analyzing the metal ions in reference materials (CASS-4, SLRS-5, 1643f, and Seronorm Trace Elements Urine L-2) and performing spike analyses of seawater, groundwater, river water, and human urine samples. Our results suggest that this 4D-printed elution-peak-guided dual-responsive monolithic packing enables lower MDLs when packed in an SPE column to facilitate the analyses of the metal ions in complex real samples.

Roles of Residual Silanol in Solid Phase Extraction of Copper to Octadecylsilyl Silica in the Presence of Acetylacetone.

Batchwise studies have demonstrated that the retention of acetylacetone (Haa) from an aqueous phase in non-endcapped octadecylsilyl (ODS) silica with silanol intentionally left (NEC) is stronger than the retention in endcapped ODS silica under ambient pressure, due to the enhanced wettability and the contribution of adsorption to silanol (-SiOH) as well as of the distribution into the ODS phase. Equilibrium analysis on solid phase extraction (SPE) of copper ion with Haa to NEC has indicated the adsorption of 1:1 species by the proton replacement reaction with silanol to give [-SiOCu(aa)] at relatively low Haa concentrations and the adsorption of [Cu(aa)2] to silanol, as well as the distribution of [Cu(aa)2] into the ODS phase. These adsorbed and distributed species of the same composition could be differentiated by ESR spectroscopy. The advantages of residual silanol in SPE of metal ions are discussed.

Magnetic solid-phase extraction of metal ions: Comparison of adding Schiff base to the extraction medium vs. magnetite modification with Schiff base

In the present work, two protocols were compared for magnetic solid phase extraction (MSPE) of Cd(II) and Pb(II) from aqueous medium. The first novel protocol involved adding Schiff base into the extraction medium using either magnetite (Mag) or magnetic carbon nanotubes (MCNT). It was found that adding vanillin Schiff base (VSB) with Mag to the extraction medium caused a double increase in the MSPE recovery and adsorption of Cd(II) and Pb(II). Unexpectedly Mag gave almost similar results as MCNT when adding VSB. Figures of merits were estimated and application on real water samples gave high recoveries. The second protocol involved magnetite modified with Schiff bases. Comparing both protocols revealed that the first protocol is better than the second protocol in terms of application on real waters and adsorption capacity. Furthermore, the first protocol avoided sorbent modification and offered a wider working pH range for Pb(II); while the second protocol offered re-usability of the Schiff base modified sorbent and avoided repetitive Schiff base preparation.

Conductive polyaniline-graphene oxide sorbent for electrochemically assisted solid-phase extraction of lead ions in aqueous food samples

This work describes an electrochemical-assisted desorption method that has been developed for solid-phase extraction of metal ions (Pb2+), based on a well-ordered conducting sorbent: an array-like polyaniline nanofiber synthesized on the surface of graphene oxide (PANI-GO). Combining the advantages of the allowable mechanical deformation of GO with the reduced ionic-diffusion path of vertical PANI nanofibers, this method’s synergistic effect lends the prepared sorbent an enhanced stability and high analyte-desorption effectiveness. In terms of the adsorption and electrochemical-assisted desorption behavior of PANI-GO, the paper reports that the adsorption/desorption process is accompanied by the changes of the as-prepared sorbent in cyclic voltammetry, and that the prepared PANI-GO exhibits good anti-interference properties across various interference ions. Given optimal pH values, the limit of detection of the proposed method is 0.04 μg L−1; the repeatability relative standard deviation (RSD) and reproducibility RSD are 1.97% and 2.51%, respectively; and the method shows good recovery capability in the case of real beverage samples spiked with Pb2+.

Adsorption Studies of Zn (II) onto Nano- Biomaterials from Aqueous Media

Hydroxyapatite and β-tricalcium phosphate as a porous composites were prepared by a sol-gel process. We got a solid powder form composites as small particles. Mixed powder by ultrasonically dispersed throughout the aqueous solution containing an optimum amount of Ring-opening- polymerization was used for the preparation of a poly(d,l-lactide-co-glycolide Acid hydrogel polymer -functionalized polymer to appropriate for solid-phase extraction of metal ions from aqueous solutions. Resins were prepared by the copolymerization of the efficacious monomer. After the sol-gel process. Then, the nano-compound materials were used as absorbents to remove zinc ions from the aqueous solutions. The adsorption behaviors of nano-composites had been studied also. Experimental results revealed that the n-HAP/PLGA-β-TCP had greater adsorption capacity than nHAP/ β-TCP , and poly(d,l-lactide-co-glycolide Acid played vital role for the adsorption of Zinc ions. Moreover, the adsorption isotherms were applied by the two models Langmuir and Freundlich , The adsorption of metal ions can be explained the effect of composites recycle on the adsorption process on the cations by the Langmuir and Freundlich models effect and show the fitting of Zn(II) adsorption of correlation coefficient the Freundlich model is the best than Langmuir model

Biosorbents for solid-phase extraction of toxic elements in waters

Some trace metals are highly toxic for the environment. There is therefore a need for reliable methods for the determination of metals at trace levels. To this end, new sample pretreatment methods such as separation, preconcentration and speciation prior to the determination of metal ions have developed rapidly. Biosorption has become a major tool for solid-phase extraction methods. This review covers selected biosorbents such as algae, bacteria, filamentous fungi and yeasts, as new sorbents used in the solid-phase extraction of metal ions from various water sample matrices. A survey of the literature over 2004-2014 shows possible applications of selected new sorbents available for use in trace metal analysis in waters using solidphase extraction. We highlight the preconcentration of the toxic elements prior to their determination by atomic spectrometry.

Immobilization of Guanazyl Functional Groups on Silica for Solid-Phase Extraction of Metal Ions

Guanazyl groups were grafted on silica gel by 4-nitrobenzoyl chloride acylation, sodium dithionite reduction, diazotation, and reaction with 2-benzylidenehydrazinecarboximidamide. The modified silica gel was used for separation and preconcentration of Cu(II), Ni(II), Cd(II), and Co(II). Quantitative extraction of the ions was achieved after 30 min and at the optimal pH of 7.5–8 at an initial concentration of 2 mg L−1. Analysis of metal sorption isotherms allowed estimation of the sorbent's interaction efficacy under static conditions at optimal pH. Distribution coefficients were determined to be 3 ± 0.3 L g−1 for Ni(II), 3 ± 0.3 L g−1 for Co(II), 1.6 ± 0.2 L g−1 for Cd(II), and 4.6 ± 0.4 L g−1 for Cu(II) at 20–60 µg analyte. The applicability of pseudo-second order kinetic equations for metal sorption kinetics description was investigated. Chemically modified silica was used for solid-phase extraction of the metal ions to improve the detection limit using X-ray fluorescence spectrometry. The method was employed for the determination of Cu(II) in water with a low limit of detection, high accuracy, and good precision.

Potential of sawdust as a green and economical sorbent for simultaneous preconcentration of trace amounts of cadmium, cobalt, and lead from water, biological, food, and herbal samples.

Application of treated sawdust with NaOH as a green and economical sorbent for simultaneous preconcentration of trace amounts of Cd(II), Co(II), and Pb(II) ions from liver, lettuce, fish, and water as test samples with complicated matrices was investigated. Various parameters, such as effect of pH and contact time, breakthrough volume, type, and concentration of eluent and interference of ions were studied. The sorption was quantitative in the pH of 5.0 to 7.0 and desorption occurred instantaneously with 5.0mL of mixed solutions of ethanol and 2.0mol/L HNO3 -HCl and the amount of ions was measured by using flame atomic absorption spectrometry. Linearity was maintained at 3 to 500μg/L for cobalt, 5.0 to 800μg/L for lead, and 2.0 to 300μg/L for cadmium in the original solution. The relative standard deviation was less than 1.80% (n= 6, with concentration of 0.3mg/L for cadmium and 0.5mg/L for lead and cobalt). Detection limits and maximum capacity of the sorbent for Co (II), Cd (II), and Pb (II) in the original solution were 0.86, 0.50, and 1.7μg/L and 28.5, 30.6, and 47.3mg/g, respectively. The results for spiked real samples, effect of interfering ions, and adsorption capacity indicated that the applicability of this method for lead preconcentration is better than cadmium and cobalt preconcentration from complicated matrices. Practical Application: Sawdust can be applied as a green and economical sorbent for simultaneous preconcentration and solid-phase extraction of metal ions from food and environmental samples with complicated matrices.

Uranium concentration in ground water samples belonging to some areas of Western Haryana, India using fission track registration technique

Incharge, Chemical Laboratory, Central Region Atomic Minerals Directorate for Exploration and Research Department of Atomic Energy, Civil Lines, Nagpur-440001(MS), India E-mail: dpsr2002@yahoo.com Dear Editor, I have read the above cited paper very carefully. The undersigned has been involved in the analysis of geological materials and hydro-geochemical reconnaissance surveys attached with mobile geochemical laboratories in different parts of India for uranium exploration activities of the Atomic Minerals Directorate for Exploration and Research. I have also contributed on uranium determination in diverse matrices vide my publications: 1. Rathore DPS, Kumar M, Tarafder PK (2012). Presentation of differential laser-induced fluorimetry as a reference measurement procedure for determination of total uranium content in ores and similar matrices. Accred. Qual. Assur. 17:75-84 2. Rathore DPS (2008). Advances in Technologies for the Measurement of Uranium in Diverse Matrices (Review article). Talanta 77:9-20. 3. Rathore DPS (2007). Trends in the Methods of Measurement in Analytical Chemistry. Explor. Res. At. Miner. 17:145-149. 4. Rathore DPS, Kumar M (2004). Analytical Applications of a Differential Technique in Laser-Induced Fluorimetry: Accurate and Precise Determination of Uranium in Concentrates and for Designing Microchemielectronic Devices for on-line Determination in Processing Industries. Talanta 62:343-349. 6. Tarafder PK, Kunkal L, Murugan P, Rathore DPS (2002). Ion-associate Solvent Extraction of Uranium with 2,3-Dihydroxynaphthalene and Cetyltrimethylammoniumbromide, and its fluorimetric Determination in Silicate Rocks. Radioanal. Nucl. Chem. 253:135-142. 7. Manjeet Kumar, Rathore DPS, Singh AK (2001). Quinalizarin Anchored on Amberlite XAD-2: A New Matrix for Solid-Phase Extraction of Metal Ions for Flame Atomic Absorption Spectrometric Determination. Fresenius J. Anal. Chem. 370:377-383. 8. Kumar M, Rathore DPS, Singh AK (2001). Pyrogallol Immobilized Amberlite XAD-2: A Newly Designed Collector for Enrichment of Metal Ions Prior to their Determination by Flame Atomic Absorption Spectrometry. Mikrochimica Acta 137:127-135. 9. Rathore DPS, Tarafder PK, Kayal M, Kumar M (2001). Application of a Differential Technique in Laser-Induced Fluorimetry: Simple and a Precise Method for the Direct Determination of Uranium in Mineralised Rocks at Percentage Level. Anal. Chim. Acta 434:201-208. 10. Kumar M, Rathore DPS, Singh AK (2000). Metal Ion Enrichment on Amberlite XAD-2 Functionalized with Tiron: Analytical Applications. Analyst 125:1221-1226.

Solid-phase extraction of metal ions from fuel ethanol with a nanostructured adsorbent

This work describes the synthesis and characterization of a new octakis[3-(2,2′-dipyridylamine)propyl]octasilsesquioxane (T8-Pr-DPA), and a study of the metal ion preconcentration in fuel ethanol. Batch and column experiments were conducted to investigate for the removal of heavy metal ions from fuel ethanol. The results showed that the Langmuir allowed to describe the sorption equilibrium data of the metal ions on T8-Pr-DPA in a satisfactory way. The following maximum adsorption capacities (in mmolg−1) were determined: 3.62 for Fe (III), 3.32 for Cr (III), 2.15 for Cu (II), 1.80 for Co (II), 1.62 for Pb (II), 1.32 for Ni (II) and 0.88 for Zn (II). The thermodynamic parameters for the adsorption process such as free energy of adsorption (ΔG), enthalpy of adsorption (ΔH) and entropy of adsorption (ΔS) were calculated. Thermodynamic parameters showed that the system has favorable enthalpic, Gibbs free energy, and entropic values. The sorption–desorption of the metal ions has made possible the development of a preconcentration and determination method of metal ions at trace level in fuel ethanol. The method of quantitative analysis for Fe, Cu, Ni and Zn in fuel ethanol by Flame AAS was validated. Several parameters have been taken into account and evaluated for the validation of method, namely: linearity, limit of detection, limit of quantification, and the relative standard deviation and accuracy. The accuracy of the method was assessed by testing analyte recovery in the fuel ethanol samples.

High-throughput solid-phase extraction of metal ions using an iminodiacetate chelating porous disk prepared by graft polymerization

A chelating porous sheet for use in solid-phase extraction was prepared by radiation-induced graft polymerization and subsequent chemical modifications. An epoxy-group-containing vinyl monomer was graft-polymerized onto a porous sheet made of polyethylene. The produced epoxy group of the graft chain was converted into an iminodiacetate group. The chelating porous sheet with a density of the iminodiacetate group of 2.1 mol/kg was cut into disks 13 mm in diameter to fit an empty cylindrical cartridge with a capacity of 6 mL. Breakthrough curves using the chelating-porous-disk-packed cartridge overlapped irrespective of the flow rate of the solution ranging up to 1500 mL/h because of negligible diffusional mass-transfer resistance of the copper ions to the iminodiacetate group of the graft chain.

Equilibrium Studies on the Optimization of Solid-Phase Extraction of Metal Ions with Pyrogallol-Anchored Cellulose Synthesized by a New Method and Applications of the Extraction in Metal Enrichment, Removal, and Determination

Pyrogallol is anchored onto cellulose via −NH−CH2−CH2−NH−SO2−C6H4−NN− linker to prepare an effective sorbent for solid-phase extraction of Cu(II), Zn(II), Fe(III), Ni(II), Co(II), Cd(II), and Pb(II) from aqueous solutions. The modified cellulose is characterized by FT-IR, 13C CPMAS NMR, TGA, and elemental analyses. The conditions for effective sorption are optimized with respect to different experimental parameters in both batch and column processes. The feasibility of the sorption process was judged from both kinetic and thermodynamic points of view. The lower limit of detection as well as the enrichment factor for each metal ion was evaluated. Analytical utility of the solid-phase extraction is illustrated by successful determination of metal ions in natural water, pharmaceutical, and milk samples by flame AAS coupled with enrichment on cellulose loaded with pyrogallol.

Quinalizarin anchored on Amberlite XAD-2. A new matrix for solid-phase extraction of metal ions for flame atomic absorption spectrometric determination.

Amberlite XAD-2 has been functionalized by coupling it to quinalizarin [1,2,5,8-tetrahydroxyanthraquinone] by means of an -N = N- spacer. Elemental analysis, thermogravimetric analysis, and infrared spectra were used to characterize the resulting new polymer matrix. The matrix has been used to preconcentrate Cu(II), Cd(II), Co(II), Pb(II), Zn(II), and Mn(II) before their determination by flame atomic absorption spectrometry (FAAS). UO2(II) has been preconcentrated for fluorimetric determination. The optimum pH values for maximum adsorption of the metals are between 5.0 and 7.0. All these metal ions are desorbed (recovery 91-99%) with 4 mol L(-1) HNO3. The adsorptive capacity of the resin was found to be in the range 0.94-5.28 mg metal g(-1) resin and loading half-life (t1/2) between 5.3 and 15.0 min. The effects of NaF, NaCl, NaNO3, Na2SO4, Na3PO4, Ca(II), and Mg(II) on the adsorption of these metal ions (0.2 microg mL(-1)) are reported. The lower limits of detection for these metal ions are between 1 and 15.0 microg L(-1). After enrichment on this matrix flame AAS has been used to determine these metal ions (except the uranyl ion) in river water samples (RSD < or = 6.5%); fluorimetry was used to determine uranyl ion in well water samples (RSD < or = 6.3%). Cobalt from pharmaceutical vitamin tablets was preconcentrated by use of this chelating resin and estimated by FAAS (RSD approximately 4%).

Dipyridyl Amide-Functionalized Polymers Prepared by Ring-Opening-Metathesis Polymerization (ROMP) for the Selective Extraction of Mercury and Palladium

Ring-opening-metathesis polymerization (ROMP) was used for the preparation of a dipyridylcarbamide-functionalized polymer suitable for solid-phase extraction of metal ions from aqueous solutions. Resins were prepared by the copolymerization of the functional monomer N,N-di-2-pyridyl-endo-norborn-2-ene-5-carboxamide (I) with 1,4,4a,5,8,8a-hexahydro-1,4,5,8-exo-endo-dimethanonaphthalene (II), using the well-defined Schrock catalyst Mo(N-2,6-i-Pr2C6H3)CHCMe2Ph(OCMe(CF3)2)2 (III). The polymerization proceeds in a living manner, allowing the stoichiometric buildup of polymers. NMR investigations proved the expected backbone structure of the resulting polymers, where the binding site of the monomer remains unaffected in course of the polymerization. The new materials were investigated in terms of their complexation behavior versus a large variety of mono-, di-, tri-, and tetravalent metal ions employing UV−vis spectroscopy as well as AAS and ICP−OES techniques. The polymer-bound dipyridylamide ligand showed exc...

Solid-phase extraction of metal ions and their estimation in vitamins, steel and milk using 3-hydroxy-2-methyl-1,4-naphthoquinone-immobilized silica gel

3-Hydroxy-2-methyl-1,4-naphthoquinone-immobilized silica gel has been used for the adsorption and estimation of copper, cobalt, iron and zinc by both batch and column techniques. The distribution coefficient D determined for each metal ion was as follows (ml g 1): Fe, 3.6 × 10 2; Cu, 3.9 × 10 2; Co, 3.8 × 10 2; Zn, 4.1 × 10 2. Methods have been developed to estimate zinc, copper and cobalt in milk, steel and vitamin samples respectively.