Chemically-modified activated carbon with ethylenediamine for selective solid-phase extraction and preconcentration of metal ions

A new method that utilizes ethylenediamine-modified activated carbon (AC-EDA) as a solid-phase extractant has been developed for simultaneous preconcentration of trace Cr(III), Fe(III), Hg(II) and Pb(II) prior to the measurement by inductively coupled plasma optical emission spectrometry (ICP-OES). The new sorbent was prepared by oxidative surface modification. Experimental conditions for effective adsorption of trace levels of Cr(III), Fe(III), Hg(II) and Pb(II) 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 new sorbent was 4.0. Complete elution of absorbed metal ions from the sorbent surface was carried out using 3.0 mL of 2% (%w/w) thiourea and 0.5 mol L⁻¹ HCl solution. Common coexisting ions did not interfere with the separation and determination of target metal ions. The maximum static adsorption capacity of the sorbent at optimum conditions was found to be 39.4, 28.9, 60.5 and 49.9 mg g⁻¹ for Cr(III), Fe(III), Hg(II) and Pb(II), respectively. The time for 94% adsorption of target metal ions was less than 2 min. The detection limits of the method was found to be 0.28, 0.22, 0.09 and 0.17 ng mL⁻¹ for Cr(III), Fe(III), Hg(II) and Pb(II), respectively. The precision (R.S.D.) of the method was lower 4.0% (n = 8). The prepared sorbent as solid-phase extractant was successfully applied for the preconcentration of trace Cr(III), Fe(III), Hg(II) and Pb(II) in natural and certified samples with satisfactory results.     

Highly efficient adsorbing noble metal ions by 3,4-dihydroxycinnamic acid-modified activated carbon

A method was established for the preconcentration of trace Au(III), Pd(II) and Pt(IV) by activated carbon modified with 3,4-dihydroxycinnamic acid. The separation and preconcentration conditions of analytes were investigated, such as effects of pH, the contacting time, the sample ?ow rate and volume, the elution condition and the interfering ions. At a pH of 1.0, the maximum static sorption capacity of the sorbent was found to be 374.8, 96.6 and 137.5 mg g^?1 for Au(III), Pd(II) and Pt(IV), respectively. The adsorbed metal ions were effectively eluted with 2.0 mL of 4% thiourea in 0.5 M HCl solution and determined by inductively coupled plasma optical emission spectrometry. The detection limit (3σ) of this method defined by IUPAC was found to be 0.12, 0.18 and 0.32 ?g L^?1 for Au(III), Pd(II) and Pt(IV), respectively. The relative standard deviation (RSD) was lower than 3.0% (n = 8) towards standard solutions. The method has been validated by analysing certified reference materials and successfully applied to the determination of trace Au(III), Pd(II) and Pt(IV) in road sediments samples.     

Solid-phase extraction of Hg(II) on creatine modified activated carbon and determination by ICP-OES in water samples

A new sorbent was successfully prepared by immobilizing creatine on activated carbon and then used for separation/preconcentration of trace Hg(II) prior to detection by inductively coupled plasma optical emission spectrometry (ICP-OES). Experimental conditions including pH, sample flow rate and volume, eluting variables and tolerance limit of interfering ions were evaluated and established. At pH 1.0 and flow rate of 2.5?mL?min^?1, Hg(II) was adsorbed quantitatively on the column, then quantitatively eluted by 2.0?mL 0.1?mol?L^?1 nitric acid solution; other transition metal ions did not interfere with the determination of Hg(II). An enrichment factor of 100 was obtained for Hg(II). The maximum adsorption capacity was 49.5?mg?g^?1. Under the optimal conditions, the value of the detection limit (3σ) was 0.06?ng?mL^?1, and the relative standard deviation (RSD) calculated was lower than 3.0% (n?=?8). The methodology was validated by analyzing certified reference materials and successfully applied to the determination of trace Hg(II) in natural water samples with satisfactory results.     

1-(2-Formamidoethyl)-3-phenylurea functionalized activated carbon for selective solid-phase extraction and preconcentration of metal ions

A novel method that utilizes 1-(2-formamidoethyl)-3-phenylurea-modified activated carbon (AC-1-(2-formamidoethyl)-3-phenylurea) as a solid-phase extractant has been developed for simultaneous preconcentration of trace Cr(III), Cu(II), Fe(III) and Pb(II) prior to the measurement by inductively coupled plasma atomic emission spectrometry (ICP-AES). Experimental conditions for effective adsorption of trace levels of Cr(III), Cu(II), Fe(III) and Pb(II) were optimized using batch and column procedures in detail. The optimum pH value for the separation of metal ions simultaneously on the new sorbent was 4. And the adsorbed metal ions could be completely eluted by using 2.0 mL 2.0 mol L⁻¹ HCl solution. Common coexisting ions did not interfere with the separation and determination of target metal ions. The maximum static adsorption capacity of the sorbent at optimum conditions was found to be 39.8, 39.9, 77.8 and 17.3 mg g⁻¹ for Cr(III), Cu(II), Fe(III) and Pb(II), respectively. The detection limits of the method were found to be 0.15, 0.41, 0.27 and 0.36 ng mL⁻¹ for Cr(III), Cu(II), Fe(III) and Pb(II), respectively. The relative standard deviation (RSD) of the method was lower than 4.0% (n = 8). The method was successfully applied for the preconcentration of trace Cr(III), Cu(II), Fe(III) and Pb(II) in natural and certified samples with satisfactory results.     

电感耦合等离子体原子发射光谱法同时测定高强度玻璃纤维粉体中9种金属元素

建立电感耦合等离子体原子发射光谱法测定高强度玻璃纤维粉体中铝、镁、钙、铁、钛、锂、铈、钠、钾9种金属元素含量的方法。采用氢氟酸、高氯酸和盐酸分两段溶解样品,分别在选定的各元素分析谱线下,采用电感耦合等离子体原子发射光谱仪测定各元素含量。9种金属元素在各自的质量浓度范围内与光谱强度成良好的线性关系,相关系数均大于0.999,检出限为8.0~17.4 μg/g。测定结果的相对标准偏差小于1.8%(n=6),加标回收率为97.6%~103.7%。该方法准确,简便,快速,适用于高强度玻璃纤维中多金属元素的同时测定。     

Chemically modified silica gel for selective solid-phase extraction and preconcentration of heavy metal ions

This paper describes our research on the synthesis of the sorbent with chemically bonded ketoimine groups, and, furthermore, using this sorbent in the SPE technique to extract and preconcentrate trace amounts of metal ions in water samples. Surface characteristics of the sorbent were determined by elemental analysis, NMR spectra for the solid phases (²⁹Si CP MAS NMR), and analysis of pore size distribution of the sorbent and nitrogen adsorption-desorption. The newly proposed sorbent with ketoimine groups was applied for the extraction and preconcentration of trace amounts of Cu (II), Cr (III) and Zn (II) ions from the water from a lake, post-industrial water and purified water unburdened back to the lake. The determination of the transition-metal ions was performed on an emission spectroscope with inductively coupled plasma ICP-OES. For the batch method, the optimum pH range for Cu (II) and Cr (III) extraction was equal to 5, and Zn(II)–to 8. All the metal ions can be desorbed from SPE columns with 10?mL of 0.5?mol?HNO₃. The detection limits of the method were found to be 0.7?µg?L^?1 for Cu (II), 0.08?µg?L^?1 for Cr (III), and 0.2?µg?L^?1 for Zn (II), respectively.     

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.     

Ion-imprinted interpenetrating network gels for solid-phase extraction of heavy metal ions

In the present work, ion-imprinted interpenetrating polymer network (IPN) gels were prepared by free radical/cationic hybrid polymerisation of acrylamide (AAm) and 1,4-butanediol vinyl ether (BVE). These gels were respectively used for separation of Cu²⁺, Ni²⁺ and Zn²⁺ ions in natural water samples. Experimental conditions for effective adsorption of metal ions were optimised with respect to different experimental parameters by column procedures in detail. The optimum pH value for the adsorption of Cu²⁺, Ni²⁺ and Zn²⁺ ions on these sorbents was 6.0. Complete elution of the adsorbed metal ions from the sorbent was carried out using 1.0 mol/L of HCl solution. The optimum sample flow rate and eluent flow rate were, respectively, 1.0 and 0.3 mL/min. Common coexisting ions did not interfere with the separation and determination of the target ions. The accuracy of the proposed method was validated by analysis of the standard reference material (GBW 08301, river sediment). The measured contents of metal ions in the reference material were in good agreement with the certified values. The presented method was successfully applied for the determination of Cu²⁺, Ni²⁺ and Zn²⁺ ions in three different water samples (well water, seawater and waste water).     

茅根微量元素含量的测定

用电感耦合等离子体发射光谱仪（ICP）测定了湛江地区产的中药茅根微量元素的含量。结果表明,其钙、镁、铁、锌等元素的含量都比较丰富,测定方法的相对标准偏差为0．12％～4．03％,回收率为97．0％～102．0％,本法简便、快速,具有较高的准确性和重现性,适用于实际分析。     

Removal of Lead(II), Cadmium(II), and Arsenic(III) from Aqueous Solution Using Magnetite Nanoparticles Prepared by Green Synthesis with Box–Behnken Design

Two types of magnetite (Fe₃O₄) nanoparticles were investigated as adsorbents for the simultaneous removal of Pb(II), Cd(II), and As(III) metal ions from aqueous solution. Magnetite nanoparticles were prepared by two synthesis procedures, both using water as solvent, and are referred to as conventional Fe₃O₄ nanoparticles and green Fe₃O₄ nanoparticles. The latter used Citrus limon (lemon) aqueous peel extract as the surfactant. Box–Behnken experimental design was used to investigate the effects of parameters such as initial concentration (20–150?mg?L^?1), pH (2–9), and biomass dosage (1–5?g?L^?1) on the removal of Pb(II), Cd(II), and As(III) ions. The optimum parameters for removal of the studied metal ions from aqueous solutions, including the initial ion concentration (20?mg?L^?1), pH (5.5) and adsorbent dose (5?g?L^?1), were determined. The pseudosecond-order model exhibited the best fit for the kinetic studies, while adsorption equilibrium isotherms were best described by Langmuir and Freundlich models. The optimum conditions were applied for the treatment wastewater. The removal efficiencies of Pb(II), Cd(II), and As(III) using the conventional and green synthesized Fe₃O₄ nanoparticles were 59.4?±?4.3, 18.7?±?1.9 and 17.5?±?1.6, and 98.8?±?5.6, 46.0?±?1.3, and 48.2?±?2.6%, respectively. These results demonstrate the potential of magnetite nanoparticles synthesized using C. limon peel extract as highly efficient adsorbents for the removal of Pb(II), Cd(II), and As(III) ions from aqueous solution.     

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.     

Selective extraction and preconcentration of cerium(IV) in water samples by cloud point extraction and determination by inductively coupled plasma optical emission spectrometry

Cloud point extraction (CPE) was used for the selective extraction and separation of cerium(IV) from aqueous solutions. The method is based on the formation of cerium(IV)-n-p-tolylbenzohydroxamic acid (n-TBHA) complex that is extracted into the micellar phase (Triton X-114) at a temperature above the cloud point temperature (CPT). After phase separation, the surfactant rich phase was diluted up to 1.0 mL and determined by inductively coupled plasma-optical emission spectrometry (ICP-OES). Under the optimum extraction conditions and instrument parameters, by preconcentration of only 10.0 mL of sample in the presence of 0.09% Triton X-114, an enhancement factor of 13.8 was obtained. The analytical curve was linear in the range of 1.5–1200 μg L⁻¹ and the detection limit was 0.4 μg L⁻¹. The method was applied to the determination of Ce(IV) in water samples with satisfactory results.     

等离子体发射光谱法测定矿山水样中硫酸盐的研究

水质中硫酸盐的测定方法很多,但对于成分复杂且盐分很高的矿山水样,传统方法操作繁琐且不环保,本文建立了等离子体发射光谱法测定矿山水样中硫酸盐的方法,样品采用硝酸和盐酸进行加热消解后既可去除硫化物,降低水质的黏度,又可实现多元素同时测定。该方法检出限为0.03mg/L,相对标准偏差为0.1～0.4%(n=6),方法具有方便,快捷,检出限低,精密度、准确度高且线性范围广的优点。     

地胆头微量元素含量的测定

用电感耦合等离子体发射光谱仪(ICP)测定了湛江地区产的中药地胆头微量元素的含量,发现其钙、镁、铁、锌等元素的含量都比较丰富。数据显示相对标准偏差为0.22%~4.45%,回收率为96.0%~102.0%,结果令人满意。     

中药牛大力微量元素含量的测定

用电感耦合等离子体发射光谱仪(ICP)测定了湛江地区产的中药牛大力微量元素的含量,发现其Ca、Mg、Fe、Zn等元素的含量都比较丰富,相对标准偏差为0.32%~7.05%,回收率为93.0%~101%,结果令人满意。     

Separation,pre-concentration and determination of trace amounts of lead(II) ions in environmental samples using two functionalised nanoporous silica gels containing a dipyridyl sub-unit

In this study, two functionalised nanoporous silica gels containing dipyridyl sub-unit (SiL1 and SiL2) as selective solid-phase extraction materials for separation, pre-concentration and determination of trace levels of Pb(II) ions by inductively coupled plasma optical emission spectroscopy (ICP-OES) was investigated. The experimental parameters including pH, amounts and type of sorbent, sample volume, eluent type and interfering ions on the recovery of the target analytes were investigated, and the optimal experimental conditions were established. Under the optimised operating conditions with the SiL2 as sorbent, an enrichment factor of 300 was obtained. The detection limit based on three times standard deviations of the blanks was 150 ng L^–1. The proposed method was applied to the determination of lead in natural and wastewater samples with satisfactory results (recoveries greater than 96.5%, RSDs lower than 5.0%).     

电感耦合等离子体光谱/质谱联机同时测定多金属结核中常量、微量、痕量元素

采用电感耦合等离子体质谱(ICP-MS)与等离子体光谱(ICP-OES)联机同时测定多金属结核样品中常量、微量、痕量元素。样品经高压密封溶样弹消解后,一次气动雾化进样,ICP-OES测定常量和微量元素,ICP-MS测定微量和痕量元素。详细探讨了不同浓度范围元素的测定方式、元素分析信号的采集模式、多原子离子干扰的校正因子。采用ICP-MS与ICP-OES二种方式同时测定Co、Cu、Ni、Zn、V、Ba、Sr,分析结果表明具有较好的一致性。所建立的ICP-MS与ICP-OES联机检测技术用于多金属结核标准样品的分析(Nod-A-1,GSPN-1,GSPN-2,GSPN-3),分析结果与推荐值符合,相对标准偏差小于10％。     

Chemically modified activated carbon with S-benzyldithiocarbazate as a new solid-phase extractant for preconcentration of mercury prior to ICP-AES determination

A new sorbent S-benzyldithiocarbazate (SBDTC) modified activated carbon (AC-SBDTC) was prepared and studied for preconcentration for trace mercury(II) prior to inductively coupled plasma atom emission spectrometry (ICP-AES). The experimental conditions were optimised with respect to different experimental parameters using both batch and column procedures in detail. The optimum pH value for the separation of Hg(II) on the new sorbent was 3, while the adsorption equilibrium was achieved in less than 5?min. Complete elution of the adsorbed metal ions from the sorbent surface was carried out using 5?mL of 0.25?mol?L^?1 of HCl and 2% CS(NH₂)₂. Common coexisting ions did not interfere with the determination. The maximum static adsorption capacity of the sorbent under optimum conditions was found to be 0.55?mmol?g^?1. The detection limit of the present method was found to be 0.09?ng?mL^?1, and the relative standard deviation (RSD) was lower than 2.0%. The procedure was validated by analysing 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 preconcentration of trace Hg(II) from the natural water samples yielding 80-fold concentration factor.     

微波消解-电感耦合等离子体原子发射光谱法同时测定工业锅炉水中的六种金属元素

应用微波消解,电感耦合等离子体原子发射光谱法同时测定锅炉水中的钙、镁、铜、铁、铝、锌六种金属元素.对射频功率、雾化气流量、分析线进行了优化.各元素校准曲线的相关系数均在0.999 5以上,检出限在0.000 7～0.006 0 mg/L之间.样品分析结果的相对标准偏差为0.48％～6.8％,加标回收率为94.0％～105％.     

On-line preconcentration and simultaneous determination of heavy metal ions by inductively coupled plasma-atomic emission spectrometry

A flow injection analysis system for on-line preconcentration and simultaneous determination of Bi³⁺, Cd²⁺, Co²⁺, Cu²⁺, Fe³⁺, Ni²⁺, Pb²⁺ and Zn²⁺ in aqueous samples by inductively coupled plasma (ICP)-atomic emission spectrometry with a charge coupled detector is described. The preconcentration of analytes is accomplished by retention of their chelates with sodium diethyldithiocarbamate in aqueous solution on a solid phase containing octadecyl silica in a minicolumn. Methanol, as eluent, is introduced into the conventional nebulizer of the ICP instrument. The effects of different parameters, including preconcentration flow rate (equal to sample flow rate (SR)), eluent flow rate (ER), weight of solid phase (W) and eluent loop volume (EV), were optimized by the super-modified simplex method. The optimum conditions were evaluated to be SR 7.2 ml min⁻¹, ER 3.5 ml min⁻¹, W of 100 mg and EV of 0.8 ml. An enrichment factor of 312.5 for each analyte was obtained. The detection limits of the proposed method for Bi³⁺, Cd²⁺, Co²⁺, Cu²⁺, Fe³⁺, Ni²⁺, Pb²⁺ and Zn²⁺ were evaluated as 1.3, 1.0, 0.8, 0.3, 14.7, 0.5, 5.5 and 0.1 ng l⁻¹, respectively. The effect of several metal ions on percent recovery was also studied. The method was applied to the recovery of these heavy metals from real matrices and to the simultaneous determination of these cations in different water samples.