Nanometer SiO2 modified with 5-sulfosalicylic acid as selective solid-phase extractant for Fe(III) determination by ICP-AES from biological and natural water samples

A new modified nanometer SiO₂ using 5-sulfosalicylic acid (SSA) as a solid-phase extractant was used for separation, preconcentration and determination of Fe(III) in aqueous solutions by inductively coupled plasma atomic emission spectrometry (ICP-AES). Its adsorption and preconcentration behaviour for Fe(III) in aqueous solutions was investigated using static procedures in detail. The optimum pH value for the separation of Fe(III) on the newly designed sorbent was 3.5. Complete elution of the adsorbed Fe(III) from the nanometer SiO₂-SSA was carried out using 2.0 mL of 0.01 mol L^− 1 of HCl. The time of 90% sorption was less than 2 min for Fe(III) at pH 3.5. Common coexisting ions did not interfere with the separation and determination of Fe(III) at pH 3.5. The maximum static adsorption capacity of the sorbent at optimum conditions was found to be 44.01 mg of Fe(III) per gram of sorbent. The relative standard deviation (RSD) of the method under optimum conditions was 3% (n = 5). The procedure was validated by analyzing three certified reference materials (GBW 08301, GBW 08504, GBW 08511), the results obtained were in good agreement with standard values. The nanometer SiO₂-SSA was successfully employed in the separation and preconcentration of the investigated Fe(III) from the biological and natural water samples yielding 100-folds concentration factor.     

Preparation of morin modified nanometer SiO<Subscript>2</Subscript> as a sorbent for solid-phase extraction of trace heavy metals from biological and natural water samples

Morin was successful as a chemical modifier to improve the reactivity of the nanometer SiO₂ surface in terms of selective binding and extraction of heavy metal ions. This new functionalized nanometer SiO₂ (nanometer SiO₂-morin) was used as an effective sorbent for the solid-phase extraction (SPE) of Cd(II), Cu(II), Ni(II), Pb(II), Zn(II) in solutions prior to its determination by inductively coupled plasma atomic emission spectrometry (ICP-AES). Experimental conditions for effective adsorption of trace levels of metal ions were optimized with respect to different experimental parameters using static and dynamic procedures in detail. The pH 4.0 was chosen as the optimum pH value for the separation of metal ions on the newly sorbent. Complete elution of the adsorbed metal ions from the nanometer SiO₂-morin was carried out using 2.0 mL of 0.5 mol L⁻¹ of HCl. Common coexisting ions did not interfere with the separation and determination at pH 4.0. The maximum static adsorption capacity of the sorbent at optimum conditions was found to be 22.36, 36.8, 40.37, 33.21 and 25.99 mg metal/g SiO₂-morin for Cd(II), Cu(II), Ni(II), Pb(II) and Zn(II), respectively. The time for 95% sorption for Cu(II) and Ni(II) and 70% sorption for Cd(II), Pb(II) and Zn(II) was less than 2 min. The relative standard deviation (RSD) of the method under optimum conditions was lower than 5.0% (n = 11). The procedure was validated by analyzing the certified reference river sediment material (GBW 08301, China), the results obtained were in good agreement with standard values. The nanometer SiO₂-morin was successfully employed in the separation and preconcentration of trace Cd(II), Cu(II), Ni(II), Pb(II) and Zn(II) from the biological and natural water samples yielding 75-folds concentration factor.     

Solid-phase extraction of trace Cu(II) Fe(III) and Zn(II) with silica gel modified with curcumin from biological and natural water samples by ICP-OES

Silica gel was firstly functionalized with aminopropyltrimethoxysilane obtaining the aminopropylsilica gel (APSG). The APSG was reacted subsequently with curcumin yielding curcumin-bonded silica gel (curcumin-APSG). This new bonded silica gel was used for separation, pre-concentration and determination of Cu(II), Fe(III), Zn(II) in biological and natural water samples by inductively coupled plasma optical emission spectrometry (ICP-OES). Experimental conditions for effective adsorption of trace levels of metal ions were optimized with respect to different experimental parameters using batch and column procedures in detail. The optimum pH value for the separation of metal ions simultaneously on the newly sorbent was 4.0. Complete elution of the adsorbed metal ions from the sorbent surface was carried out using 2.0 mL of 0.1 mol L^− 1 of HCl. Common coexisting ions did not interfere with the separation and determination at pH 4.0. The maximum static adsorption capacity of the sorbent at optimum conditions was found to be 0.63, 0.46 and 0.37 mmol g^− 1 for Cu(II), Fe(III) and Zn(II) respectively. The time for 95% sorption for Cu(II) Fe(III) and Zn(II) was less than 2 min. The detection limits of the method defined by IUPAC was found to be 0.12, 0.15 and 0.40 ng mL^− 1 for Cu(II), Fe(III) and Zn(II), respectively. The relative standard deviation (RSD) of the method under optimum conditions was lower 3.0% (n = 5). The procedure was validated by analyzing the certified reference river sediment material (GBW 08301, China), the results obtained were in good agreement with standard values. This sorbent was successfully employed in the separation and pre-concentration of trace Cu(II), Fe(III) and Zn(II) from the biological and natural water samples yielding 75-fold concentration factor.     

Selective solid phase extraction of trace cadmium(II) and lead(II) from biological and natural water samples by ofloxacin-modified-silica gel

Ofloxacin was successfully used as a chemical modifier to improve the reactivity of silica gel in terms of selective binding and extraction of heavy metal ions. This new functionalised silica gel (SG-ofloxacin) was as an effective sorbent for the solid-phase extraction (SPE) of Cd(II) and Pb(II) in biological and natural water samples and their determination by inductively coupled plasma optical emission spectrometry (ICP-OES). Experimental conditions for effective adsorption of trace levels of Cd(II) and Pb(II) were optimised with respect to different experimental parameters using the batch and column procedures. The time for 70% sorption for Cd(II) and Pb(II) was less than 2 min. Complete elution of the adsorbed metal ions from the SG-ofloxacin was carried out using 2.0 mL of 0.5 mol L^?1 of HCl. Common coexisting ions did not interfere with the separation and determination at pH 4.0. The maximum static adsorption capacity of the sorbent at optimum conditions was found to be 39.17 and 48.69 mg g^?1 for Cd(II) and Pb(II), respectively. The detection limits of the method were found to be 0.29 and 0.13 ng mL^?1 for Cd(II) and Pb(II), respectively. The relative standard deviation (RSD) of the method under optimum conditions was lower than 3.0% (n = 5). The method was applied to the recovery of Cd(II) and Pb(II) from the certified reference material (GBW 08301, river sediment) and to the simultaneous determination of these cations in different water and biological samples with satisfactory results and yielding 100-folds enrichment factor.     

On-line solid-phase extraction and multisyringe flow injection analysis of Al(III) and Fe(III) in drinking water

A new analytical method was developed for on-line monitoring of residual coagulants (aluminium and iron salts) in potable water. The determination was based on a sequential procedure coupling an extraction/enrichment step of the analytes onto a modified resin and a spectrophotometric measurement of a surfactant-sensitized binary complex formed between eluted analytes and Chrome Azurol S. The optimization of the solid phase extraction was performed using factorial design and a Doehlert matrix considering six variables: sample percolation rate, sample metal concentration, flow-through sample volume (all three directly linked to the extraction step), elution flow rate, concentration and volume of eluent (all three directly linked to the elution step). A specific reagent was elaborated for sensitive and specific spectrophotometric determination of Al(III) and Fe(III), by optimizing surfactant and ligand concentrations and buffer composition. The whole procedure was automated by a multisyringe flow injection analysis (MSFIA) system. Detection limits of 4.9 and 5.6 μg L⁻¹ were obtained for Al(III) and Fe(III) determination , respectively, and the linear calibration graph up to 300 μg L⁻¹ (both for Al(III) and Fe(III)) was well adapted to the monitoring of drinking water quality. The system was successfully applied to the on-site determination of Al(III) and Fe(III) at the outlet of two water treatment units during two periods of the year (winter and summer conditions).     

Silica gel-immobilized-vanillin derivatives as selective solid-phase extractants for determination of chromium (III) in environmental samples by ICP-OES

A method is described for the selective extraction of chromium(III) from aqueous solutions and natural water samples, based on the use of two newly synthesized solid-phase extractors via silica gel-immobilized-vanillin derivatives (I,II). Experimental conditions for effective adsorption of trace levels of Cr(III) were optimized with respect to different experimental parameters using batch and column procedures in detail. The optimum pH values for the separation of Cr(III) simultaneously on the newly sorbents were both 4.0 and complete elution of Cr(III) from the sorbents surface was carried out using 2.0 mL of 0.5 mol L^− 1 HCl. The sorption capacity of phase I towards Cr(III) was found to be 0.700 mmol g^− 1 where the sorption capacity of phase II was 0.538 mmol g^− 1. The detection limits (3σ) of the method defined by IUPAC were found to be 0.87 and 0.64 ng mL^− 1 with enrichment factors of 100 and 75 for phases I and II, respectively. The method has been applied for the determination of Cr(III) in biological materials and water samples with satisfactory results.     

Selective Determination of Trace Mercury (II) after Preconcentration with 4-(2-Pyridylazo)-Resorcinol-Modified Nanometer-Sized SiO2 Particles from Sample Solutions

A rapid, selective method that utilize 4-(2-Pyridylazo)-resorcinol (PAR)-modified nanometer SiO₂ (nanometer SiO₂–PAR) as a new solid-phase extractant for preconcentration of trace mercury (II) has been developed. The adsorption property of nanometer SiO₂–PAR for metal ions was studied by selectively extracting different metal ions from aqueous solutions. The results revealed an excellent affinity of the nanometer SiO₂–PAR for mercury (II) in presence of interfering metal ions at pH 4. The main parameters of solid-phase extraction such as shaking time, elution and sample dilution effect were studied. The extractant shows rapid kinetic sorption, and the adsorption equilibrium of mercury (II) on nanometer SiO₂–PAR was achieved in less than 2 min. The adsorbed mercury (II) was easily eluted by 4 mL of 6 mol L⁻¹ HCl. The maximum preconcentration factor was 50. The maximum static adsorption capacity was 276 μmol g⁻¹ at pH 4. The detection limit (3σ) was 0.43 μg L⁻¹ for cold vapor atomic absorption spectrometry (CVAAS), and the relative standard deviation of the eight replicate determinations was 2.4% for the determination of 2.0 μg of Hg(II) in 100 mL water sample. The method was applied to the determination of trace mercury (II) in sample solutions with satisfactory results.     

Sequential solid-phase extraction with cyanopropyl bonded-phase cartridges for trace enrichment of PCBs and chlorinated pesticides from water samples

Summary Gas chromatography of polychlorinated biphenyls and chlorinated pesticides in water samples has been performed after adsorption from a 50–250 mL sample on to a cartridge containing 100 mg cyanopropyl-bonded porous silica. The PCBs are desorbed with 500 μL ethyl acetate, which is concentrated and analysed by gas chromatography with electron-capture detection (GC-ECD). The average recovery of 1 ppb PCB congeners at from distilled water and from Marta river water is ≥95% (standard deviation ≤2.5). The average recovery of 20 ppb Aroclor 1260 from Marta river water was ≥91% (standard deviation ≤3.5). In the separation of the PCBs from the chlorinated pesticides only aldrin, heptachlor and 4,4′-DDD are adsorbed with the PCBs by the CN Sep-Pak cartridge. The method proposed is rapid, simple and reproducible.     

Chemically modified attapulgite with asparagine for selective solid-phase extraction and preconcentration of Fe(III) from environmental samples

A new method that utilizes asparagine modified attapulgite as a solid phase extractant has been developed for preconcentration of trace Fe(III) prior to the measurement by inductively coupled plasma optical emission spectrometry. Characterization of the surface modification was performed on the basis of Fourier transform infrared spectra. The separation/preconcentration conditions of the analyte were investigated, including the pH value, the shaking time, the sample ?ow rate and volume, the elution condition and the interfering ions. At pH 4, the new adsorbent had relatively high capacity and enrichment factor compared to other methods reported so far. The adsorbed Fe(III) was quantitatively eluted by 2 mL of 0.5 mol L⁻¹ HCl. Common coexisting ions did not interfere with the separation. The detection limit of the method was 0.19 μg L⁻¹. The relative standard deviation was 3.4% (n = 8) which indicated that the method had good precision for the analysis of trace Fe(III) in solution samples. The method was validated using two certified reference materials and has been applied for the determination of trace Fe(III) in biological and natural water samples with satisfactory results.     

Silica gel modified with 1-(2-aminoethyl)-3-phenylurea for selective solid-phase extraction and preconcentration of Sc(III) from environmental samples

A new method that utilizes 1-(2-aminoethyl)-3-phenylurea-modified silica gel as a solid-phase extractant has been developed for preconcentration of trace Sc(III) prior to the measurement by inductively coupled plasma atomic emission spectrometry (ICP-AES). Experimental conditions for effective adsorption of trace level of Sc(III) were optimized using batch and column procedures in detail. The optimum pH value for the separation of Sc(III) on the new sorbent was 4 and complete elution of Sc(III) from the sorbent surface was carried out using 1.0 mL of 0.1 mol L⁻¹ HCl. Common coexisting ions did not interfere with the separation and determination of the analyte. The maximum static adsorption capacity of the sorbent at optimum conditions was found to be 32.5 mg g⁻¹ while the time of 95% adsorption was less than 2 min. The detection limit of present method was found to be 0.091 μg g⁻¹, and the relative standard deviation (RSD) was lower than 3.0% (n = 8). The method was successfully applied for the preconcentration of trace Sc(III) in the environmental samples with satisfactory results.     

Chemically modified silica gel with p-dimethylaminobenzaldehyde for selective solid-phase extraction and preconcentration of Cr(III), Cu(II), Ni(II), Pb(II) and Zn(II) by ICP-OES

Silica gel-bound amines phase modified with p-dimethylaminobenzaldehyde (p-DMABD) was prepared based on chemical immobilization technique. The product (SG-p-DMABD) was used as an adsorbent for the solid-phase extraction (SPE) Cr(III), Cu(II), Ni(II), Pb(II) and Zn(II) prior to their determination by inductively coupled plasma optical emission spectrometry (ICP-OES). The uptake behaviors of SG-p-DMABD for extracting these metal ions were studied using batch and column procedures. For the batch method, the optimum pH range for Cr(III) and Ni(II) extraction was ≥ 3, for Cu(II), Pb(II) and Zn(II) extraction it was ≥ 4. For simultaneous enrichment and determination of all the metals on the newly designed adsorbent, the pH value if 4.0 was selected. All the metal ions can be desorbed with 2.0 mL of 0.5 mol L^− 1 of HCl. The results indicate that SG-p-DMABD has rapid adsorption kinetics using the batch method. The adsorption capacity for these metal ions is in the range of 0.40-1.15 mmol g^− 1, with a high enrichment factor of 125. The presence of commonly coexisting ions does not affect the sorption capacities. The detection limits of the method were found to be 1.10, 0.69, 0.99, 1.10 and 6.50 μg L^− 1 for Cr(III), Cu(II), Ni(II), Pb(II) and Zn(II), respectively. The relative standard deviation (RSD) of the method under optimum conditions was 5.0% (n = 8) for all metal ions. The method was applied to the preconcentration of Cr(III), Cu(II), Ni(II), Pb(II) and Zn(II) from the certified reference material (GBW 08301, river sediment) and water samples with satisfactory results.     

Solid-phase extraction and preconcentration of trace Pb(II) from water samples with folic acid modified silica gel

A chelating matrix prepared by immobilising folic acid on silica gel-bound amine phase was used as a new solid-phase extractant. This sorbent has been developed only for preconcentration of trace Pb(II) prior to determination by inductively coupled plasma atomic emission spectrometry (ICP-AES). Experimental conditions were investigated by batch and column procedures. The optimum pH value for the separation of Pb(II) on the new sorbent was 4.0. The adsorbed Pb(II) was quantitatively eluted by 2.0?cm³ of 0.5?mol?dm^?3 of HCl. Common coexisting ions did not interfere with the separation and determination of Pb(II). The maximum static adsorption capacity of the sorbent under optimum conditions was found to be 69.23?mg?g^?1 for Pb(II). The detection limit of the method defined by International Union of Pure and Applied Chemistry was 0.28?ng?cm^?3. The relative standard deviation (RSD) of the method was lower than 2.0% (n?=?8). The developed method has been validated by analysing certified reference materials and successfully applied to the determination of Pb(II) in water samples with satisfactory results.     

Use of solid-phase extraction to enable enhanced detection of acyl homoserine lactones (AHLs) in environmental samples

A challenge for understanding the role of bacterial cell–cell signalling in the environment is the detection of those signals, which are often present in low (nmol L⁻¹) concentrations. We describe here a simple purification method, solid-phase extraction (SPE), for increasing the sensitivity of detection for one such group of signals, acyl homoserine lactones (AHLs), in environmental samples. Spiking of dried marine sponge tissue (Stylinos sp.) with AHLs resulted in detection down to 0.01 ppm for 3-oxo-hexanoyl homoserine lactone (3-oxo C₆-HSL) and 1 ppm for hexanoyl homoserine lactone (C₆-HSL). Compared with liquid extraction methods use of SPE resulted in twofold and tenfold improvements in sensitivity, respectively.     

Selective solid-phase extraction of nickel(II) using a surface-imprinted silica gel sorbent

A new Ni(II)-imprinted amino-functionalized silica gel sorbent with excellent selectivity for nickel(II) was prepared by an easy one-step reaction by combining a surface imprinting technique for selective solid-phase extraction (SPE) of trace Ni(II) in water samples prior to its determination by inductively coupled plasma atomic emission spectrometry (ICP-AES). Compared with non-imprinted polymer particles, the ion-imprinted polymers (IIPs) had higher selectivity and adsorption capacity for Ni(II). The maximum static adsorption capacity of the ion-imprinted and non-imprinted sorbent for Ni(II) was 12.61 and 4.25 mg g⁻¹, respectively. The relatively selective factor (α_r) values of Ni(II)/Cu(II), Ni(II)/Co(II), Ni(II)/Zn(II) and Ni(II)/Pd(II) were 45.99, 32.83, 43.79 and 28.36, which were greater than 1. The distribution ratio (D) values of Ni(II)-imprinted polymers for Ni(II) were greatly larger than that for Cu(II), Co(II), Zn(II) and Pd(II). The detection limit (3σ) was 0.16 ng mL⁻¹. The relative standard deviation of the method was 1.48% for eight replicate determinations. The method was validated by analyzing two certified reference materials (GBW 08618 and GBW 08402), the results obtained is in good agreement with standard values. The developed method was also successfully applied to the determination of trace nickel in plants and water samples with satisfactory results.     

Solid-phase extraction of iron(III) with an ion-imprinted functionalized silica gel sorbent prepared by a surface imprinting technique

A new Fe(III)-imprinted amino-functionalized silica gel sorbent was prepared by a surface imprinting technique for selective solid-phase extraction (SPE) of Fe(III) prior to its determination by inductively coupled plasma atomic emission spectrometry (ICP-AES). Compared with non-imprinted polymer particles, the ion-imprinted polymers (IIPs) had higher selectivity and adsorption capacity for Fe(III). The maximum static adsorption capacity of the ion-imprinted and non-imprinted sorbent for Fe(III) was 25.21 and 5.10 mg g⁻¹, respectively. The largest selectivity coefficient of the Fe(III)-imprinted sorbent for Fe(III) in the presence of Cr(III) was over 450. The relatively selective factor (α_r) values of Fe(III)/Cr(III) were 49.9 and 42.4, which were greater than 1. The distribution ratio (D) values of Fe(III)-imprinted polymers for Fe(III) were greatly larger than that for Cr(III). The detection limit (3σ) was 0.34 μg L⁻¹. The relative standard deviation of the method was 1.50% for eight replicate determinations. The method was validated by analyzing two certified reference materials (GBW 08301 and GBW 08303), the results obtained is in good agreement with standard values. The developed method was also successfully applied to the determination of trace iron in plants and water samples with satisfactory results.     

Micromorphology Characterization of SiO2-Based Composite Thin Films with Immobilized Terbium(III) Complex

The aim of this study was to investigate by atomic force microscopy and multifractal analysis the three-dimensional (3-D) of surface micromorphology of the complex of Tb(III) with the biscoumarin derivative 3,3′-[(4-hydroxyphenyl)methyl)]bis-(4-hydroxy-2H-1-benzopyran-2-one), Tb(C₂₅H₁₅O₇)₃ · 5H₂O immobilized in transparent SiO₂-based films by a simple casting technique. The 3-D surfaces contain irregularities of various orders spread on the surface due to the intrinsic method of surface preparation. We found that the micromorphology of all analyzed samples has multifractal characteristics. The generalized dimension D _q and the singularity spectrum f(α) provided quantitative values that describe the degree of heterogeneity in the 3-D surface geometry at nanometer scale. The results showed that the larger the spectrum width Δα (Δα = α _max  ? α _min ) of the multifractal spectra f(α), the more nonuniform is the surface micromorphology. These results demonstrate that multifractal analysis is a more precise and reliable tool for quantitative characterization of 3-D surface micromorphology.     

Solid phase extraction and flame atomic absorption spectrometric determination of trace amounts of cadmium and lead in water and biological samples using modified TiO2 nanoparticles

A solid phase extraction procedure for the separation and preconcentration of trace amounts of Cd(II) and Pb(II) using the alizarin red S modified TiO₂ nanoparticles prior to their determination by flame atomic absorption spectrometry has been proposed. The influences of some analytical parameters such as pH, flow rates of sample and eluent, type and concentration of the eluent, and interfering ions on the recovery of Cd(II) and Pb(II) by the sorbent were investigated. The analytes were quantitatively sorbed from the aqueous solution at pH 5.5 onto a microcolumn packed with the sorbent and recovered with 2.0?mL of 1.5?mol?L^?1 hydrochloric acid. Under the optimum experimental conditions, the detection limits for Cd(II) and Pb(II) were 0.11 and 0.30?ng?mL^?1 and the relative standard deviations for ten replicate measurements of 5.0 and 50.0?ng?mL^?1 of Cd(II) and Pb(II) were 2.1 and 1.9%, respectively. A sample volume of 200?mL resulted in a preconcentration factor of 100. The method was successfully applied to the determination of Cd(II) and Pb(II) in water and biological samples, and accuracy was examined by the recovery experiments, independent analysis using electrothermal atomic absorption spectrometry, and analysis of a water standard reference material (SRM 1643e).     

Novel thionin-functionalised core shell magnetic nanoparticles for dispersive solid-phase extraction of Hg(II) in food and water samples

To develop an accurate and precise method for separation and pre-concentration of Hg(II), a novel thionin functionalised core shell structure magnetic material has been prepared and characterised. The extraction ability of the material was evaluated by magnetic solid-phase extraction coupled with inductively coupled plasma mass spectrometry determination of Hg(II) in food and water samples. Combining the advantages of magnetic separation with selective extraction of thionin towards Hg(II), the material exhibits enhanced enrich selectivity and efficiency for Hg(II). The experimental parameters influencing Hg(II) extraction efficiency, including pH of the aqueous solution, the dosage of the adsorbent, extraction time and sample volume, were systematically investigated. Under the optimised conditions, concentration of Hg(II) at 1.0 μg L^?1 can be successfully enriched by the material without the interference of the common co-existing ions. The enrichment factor and adsorption capacity were 250 and 75.2 mg g^?1, and precise of the method was confirmed by analysing the spiked food, water samples and standard water reference samples with the recoveries of 92.5–101.8%.     

Preparation of ethyl levulinate from wheat stalk over Zr(SO4)2/SiO2

A series of Zr(SO₄)₂/SiO₂ solid acid catalysts with different Zr(SO₄)₂ loadings were prepared by water-soluble-impregnation method at room temperature. Then, the prepared catalysts were characterized by Fourier transform infrared spectroscopy, transmission electron microscopy and energy-dispersive X-ray spectrum, X-ray diffraction, adsorption/desorption of N₂, and temperature-programmed desorption of NH₃. The results showed that the active component Zr(SO₄)₂ was successfully adhered to the mesoporous SiO₂, and the acid amount of Zr(SO₄)₂/SiO₂ increased with the increasing of the Zr(SO₄)₂ loadings. Finally, the wheat stalk was used as raw material and depolymerized over Zr(SO₄)₂/SiO₂ to produce ethyl levulinate (EL). The reaction mixture was separated and purified by filtration and vacuum distillation. The kinetic characteristics and the reaction pathway were also studied. A comparative study showed that 20 wt.% Zr(SO₄)₂/SiO₂ exhibited higher catalytic activity. When reaction temperature, time, catalyst dosage and Zr(SO₄)₂ loadings were 190 °C, 50 min, 20 wt.% and 30 wt.%, the EL yield reached a maximum of 17.14%. The relative content of EL exceeded 90% after three steps of distillation.     

Silica gel surface modified with sulfanilamide for selective solid-phase extraction of Cu(II), Zn(II) and Ni(II)

A new chelating matrix has been prepared by immobilising sulfanilamide (SA) on silica gel (SG) surface modified with 3-chloropropyltrimethoxysilane as a sorbent for the solid-phase extraction (SPE) Cu(II), Zn(II) and Ni(II). The determination of metal ions in aqueous solutions was carried out by inductively coupled plasma optical emission spectrometry (ICP-OES). Experimental conditions for effective sorption of trace levels of Cu(II), Zn(II) and Ni(II) were optimised with respect to different experimental parameters using the batch and column procedures. The presence of common coexisting ions does not affect the sorption capacities. The maximum sorption capacity of the sorbent at optimum conditions was found to be 34.91, 19.07 and 23.62 mg g^?1 for Cu(II), Zn(II) and Ni(II), respectively. The detection limit of the method defined by IUPAC was found to be 1.60, 0.50 and 0.61 µg L^?1 for Cu(II), Zn(II) and Ni(II), respectively. The relative standard deviation (RSD) of the method under optimum conditions was 4.0% (n = 8). The method was applied to the recovery of Cu(II), Zn(II) and Ni(II) from the certified reference material (GBW 08301, river sediment) and to the simultaneous determination of these cations in different water samples with satisfactory results.