An off-line automated preconcentration system with ethylenediaminetriacetate chelating resin for the determination of trace metals in seawater by high-resolution inductively coupled plasma mass spectrometry

A novel automated off-line preconcentration system for trace metals (Al, Mn, Fe, Co, Ni, Cu, Zn, Cd, and Pb) in seawater was developed by improving a commercially available solid-phase extraction system SPE-100 (Hiranuma Sangyo). The utilized chelating resin was NOBIAS Chelate-PA1 (Hitachi High-Technologies) with ethylenediaminetriacetic acid and iminodiacetic acid functional groups. Parts of the 8-way valve made of alumina and zirconia in the original SPE-100 system were replaced with parts made of polychlorotrifluoroethylene in order to reduce contamination of trace metals. The eluent pass was altered for the back flush elution of trace metals. We optimized the cleaning procedures for the chelating resin column and flow lines of the preconcentration system, and developed a preconcentration procedure, which required less labor and led to a superior performance compared to manual preconcentration (Sohrin et al. [5]). The nine trace metals were simultaneously and quantitatively preconcentrated from ∼120 g of seawater, eluted with ∼15 g of 1 M HNO₃, and determined by HR-ICP-MS using the calibration curve method. The single-step preconcentration removed more than 99.998% of Na, K, Mg, Ca, and Sr from seawater. The procedural blanks and detection limits were lower than the lowest concentrations in seawater for Mn, Ni, Cu, and Pb, while they were as low as the lowest concentrations in seawater for Al, Fe, Co, Zn, and Cd. The accuracy and precision of this method were confirmed by the analysis of reference seawater samples (CASS-5, NASS-5, GEOTRACES GS, and GD) and seawater samples for vertical distribution in the western North Pacific Ocean.     

Multielement determination of trace metals in seawater by ICP-MS with aid of down-sized chelating resin-packed minicolumn for preconcentration

The multielement determination of trace metals in seawater was carried out by inductively coupled plasma mass spectrometry (ICP-MS) with aid of a down-sized chelating resin-packed minicolumn for preconcentration. The down-sized chelating resin-packed minicolumn was constructed with two syringe filters (DISMIC 13HP and Millex-LH) and an iminodiacetate chelating resin (Chelex 100, 200-400 mesh), with which trace metals in 50 mL of original seawater sample were concentrated into 0.50 mL of 2 M nitric acid, and then 100-fold preconcentration of trace metals was achieved. Then, 0.50 mL analysis solution was subjected to the multielement determination by ICP-MS equipped with a MicroMist nebulizer for micro-sampling introduction. The preconcentration and elution parameters such as the sample-loading flow rate, the amount of 1 M ammonium acetate for elimination of matrix elements, and the amount of 2 M nitric acid for eluting trace metals were optimized to obtain good recoveries and analytical detection limits for trace metals. The analytical results for V, Mn, Co, Ni, Cu, Zn, Mo, Cd, Pb, and U in three kinds of seawater certified reference materials (CRMs; CASS-3, NASS-4, and NASS-5) agreed well with their certified values. The observed values of rare earth elements (REEs) in the above seawater CRMs were also consistent with the reference values. Therefore, the compiled reference values for the concentrations of REEs in CASS-3, NASS-4, and NASS-5 were proposed based on the observed values and reference data for REEs in these CRMs.     

Silica gel modified with N-(3-propyl)-O-phenylenediamine: functionalization, metal sorption equilibrium studies and application to metal enrichment prior to determination by flame atomic absorption spectrometry.

The use of the chemically modified silica gel N-(3-propyl)-O-phenylenediamine (SiG-NPPDA) adsorbent, for the preconcentration and separation of trace heavy metals, was described. SiG-NPPDA sorbs quantitatively (90-100% recovery) trace amounts of nine heavy metals, viz., Cd(II), Zn(II), Fe(III), Cu(II), Pb(II), Mn(II), Cr(III), Co(II) and Ni(II) at pH 7-8. The sorption capacity varies from 350 to 450 micromol g(-1). Desorption was found to be quantitative with 1-2 M HNO3 or 0.05 M Na2EDTA. The distribution coefficient, Kd and the percentage concentration of the investigated metal ions on the adsorbent at equilibrium, C(M,eqm)% (Recovery, R%), were studied as a function of experimental parameters. The logarithmic values of the distribution coefficient, log Kd, ranges between 4.0 and 6.4. Some foreign ions caused little interference in the preconcentration and determination of the investigated nine metals by flame atomic absorption spectrometry (AAS). The adsorbent and its formed metal chelates were characterized by IR (absorbance and/or reflectance), potentiometric titrations and thermogravimetric analysis (TGA and DTG). The mode of chelation between the SiG-NPPDA adsorbent and the investigated metal ions is proposed to be due to the reaction of the investigated metal ions with the two nitrogen atoms of the SiG-NPPDA adsorbent. The present adsorbent coupled with flame AAS has been used to enrich and determine the nine metal ions in natural aqueous systems and in certified reference materials (RSD < or = 5%). The copper, iron, manganese and zinc present in some pharmaceutical vitamin samples were also preconcentrated on SiG-NPPDA adsorbent and determined by flame AAS (RSD < or = 4.2%). Nanogram concentrations (0.07-0.14 ng ml(-1)) of Cd(II), Zn(II), Fe(III), Pb(II), Cr(III), Mn(II), Cu(II), Co(II) and Ni(II) can be determined reliably with a preconcentration factor of 100.     

ICP-AES determination of trace elements after preconcentrated with p-dimethylaminobenzaldehyde-modified nanometer SiO2 from sample solution

A new method that utilizes p-dimethylaminobenzaldehyde-modified nanometer SiO₂ (SiO₂-p-DMABD) 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). The preconcentration conditions of analytes were investigated, including the pH value, the shaking time, the mass of sorbent, the sample flow rate and volume, the elution condition and the interfering ions. The adsorption capacity of nanometer SiO₂-p-DMABD was found to be (mg g^− 1) Cr(III): 6.2, Cu(II): 18.6, Fe(III): 4.7 and Pb(II): 6.0 at pH 4. The adsorbed metals were quantitatively eluted with 4 mL of 1.0 mol L^− 1 HCl. According to the definition of IUPAC, the detection limits (3σ) of this method for Cr(III), Cu(II), Fe(III) and Pb(II) were 0.79, 1.27, 0.40 and 1.79 ng mL^− 1, respectively. The proposed method achieved satisfied results when it was applied to the determination of trace Cr(III), Cu(II), Fe(III) and Pb(II) in biological and water samples.     

Preconcentration and determination of trace metals in seawater using a thiol cotton fiber minicolumn coupled with inductively coupled plasma mass spectrometry.

A rapid separation and preconcentration method was developed for the determination of trace metals Cu, Zn, Cd, and Pb in seawater using a minicolumn packed with thiol cotton fiber (TCF) coupled with inductively coupled plasma mass spectrometry (ICP-MS). Preconcentration parameters, such as seawater sample volume and flow rate and eluent hydrochloric acid concentration, volume and flow rate, were optimized. Under the optimized conditions, trace metals Cu, Zn, Cd, and Pb in seawater can be determined with no interference from saline matrices. When a sample volume of 1500 ml and a sample flow rate of 15 ml min(-1) were used, the preconcentration factor of 1500 and RSD value of <7% at ng ml(-1) were achieved. The accuracy of the recommended method was verified by the analysis of certified reference materials.     

用1-亚硝基-2-萘酚修饰的微晶蒽分离富集与测定环境水中钴

建立了微晶蒽分离富集环境水样中痕量Co(II)的方法。在pH3.0条件下,1-亚硝基-2-萘酚与Co(II)形成红棕色螯合物被微晶蒽定量吸附,能使Co(II)与Pb(II)、Ni(II)、Mn(II)、Cu(II)、Cd(II)、Zn(II)、Fe(III)、Cr(III)、Al(III)等常见离子分离。本法富集倍数达100倍,检出限为0.14μg/L,回收率97.5%～105%,已应用于不同水样中Co(II)的测定。     

New test tools for determination of trace metals using polydentate cellulose

New test tools have been developed for the rapid determination of trace metals: Ag, Cd, Co, Cu(II), Fe(II,III), Hg(II), Pd and Zn, using polydentate irregular α-celluloses, containing in the 6 position the fragments heterylformazane or heterylhydrazone, with a pocket device for preconcentration. Received: 17 June 1997 / Revised: 1 November 1997 / Accepted: 6 November 1997     

New test tools for determination of trace metals using polydentate cellulose

New test tools have been developed for the rapid determination of trace metals: Ag, Cd, Co, Cu(II), Fe(II,III), Hg(II), Pd and Zn, using polydentate irregular α-celluloses, containing in the 6 position the fragments heterylformazane or heterylhydrazone, with a pocket device for preconcentration. Received: 17 June 1997 / Revised: 1 November 1997 / Accepted: 6 November 1997     

Solid Phase Extraction of Trace Metals in Seawater Using Morpholine Dithiocarbamate‐Loaded Amberlite XAD‐4 and Determination by ICP‐AES

Abstract

Application of morpholine dithiocarbamate (MDTC) coated Amberlite XAD‐4, for preconcentration of Cu(II), Cd(II), Zn(II), Pb(II), Ni(II) and Mn(II) by solid phase extraction and determination by inductively coupled plasma (ICP) atomic emission spectrometry (AES) was studied. The optimum pH values for quantitative sorption of Cu(II), Cd(II), Zn(II), Pb(II), Ni(II), and Mn(II) were 6.5–8.0, 7.0–8.5, 6.0–8.5, 6.5–8.5, 7.5–9.0, and 8.0–8.5, respectively. The metals were desorbed with 2 mol L^?1. The t_1/2 values for sorption of metal ions were 2.6, 2.9, 2.5, 2.6, 3.0, and 3.8 min respectively for Cu(II), Cd(II), Zn(II), Pb(II), Ni(II) and Mn(II). The effect of diverse ions on the determination of the previously named metals was studied. Simultaneous enrichment of the six metals was accomplished, and the method was applied for use in the determination of trace metal ions in seawater samples.     

微晶酚酞富集-分光光度法测定痕量Zn(II)

建立了一种利用修饰有结晶紫(CV^＋)的微晶酚酞作为固态吸附剂分离富集溶液中痕量Zn(II)的新方法, 富集后的Zn(II)含量可直接用光度法测定. 控制一定条件, Zn(II)能与常见阳离子Ni(II), Cd(II), Al(III), Ca(II), Mg(II), Co(II), Mn(II), Cu(II), Pb(II), Fe(III)等完全分离, 且富集时基本不受, , Br^－, Cl^－, I^－,等阴离子影响. 微晶酚酞对Zn(II)的吸附容量为25.8 mg/g; 富集因数可达200倍, 回收率在97.7%～102%之间, RSD小于2.7%. 该方法已成功应用于实际水样中Zn(II)的富集测定, 结果令人满意.     

Zinc and iron determination in serum and urine samples of thyroid patients using cloud point extraction

A simple and rapid cloud point extraction method was applied for preconcentration of trace quantities of zinc (Zn) and iron (Fe) in biological samples (serum and urine) of thyroid patients prior to determination by flame atomic absorption spectrometry. The metals in serum and urine samples were complexed with 1-(2-thiazolylazo)-2-naphthol and entrapped in the surfactant octylphenoxypolyethoxyethanol (Triton X-114). After centrifugation, the surfactant-rich phase was diluted with 0.1 M HNO3 in methanol. For optimum recovery of analytes, the influences of the analytical parameters, including pH and amounts of complexing and surfactant reagents, were investigated. Enrichment factors of 66.4 and 70.2 were obtained for the preconcentration of Zn(II) and Fe(III), respectively. The obtained results showed sufficient recoveries (>98%) for Zn(II) and Fe(III) in certified reference materials (CRMs). The proposed method was applied to the determination of Zn(II) and Fe(III) in biological (serum and urine) samples and CRMs.     

Determination of trace metals in seawater by an automated flow injection ion chromatograph pretreatment system with ICPMS

A novel flow injection ion chromatograph (FI-IC) system has been developed to fully automate pretreatment procedures for multi-elemental analysis of trace metals in seawater by inductively coupled plasma mass spectrometer (ICPMS). By combining 10-port, 2 position and 3-way valves in the FI-IC manifold, the system effectively increase sample throughput by simultaneously processing three seawater samples online for: sample loading, injection, buffering, preconcentration, matrix removal, metal elution, and sample collection. Forty-two seawater samples can be continuously processed without any manual handing. Each sample pretreatment takes about 10 min by consuming 25 mL of seawater and producing 5 mL of processed concentrated samples for multi-elemental offline analysis by ICPMS. The offline analysis improve analytical precision and significantly increase total numbers of isotopes determined by ICPMS, which include the metals Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Ti, V, and Zn. The blank value and detection limits of trace metals using the system with ICPMS analysis all range from 0.1 to 10 parts per trillion (ppt), except Al, Fe, and Zn. The accuracy of the pretreatment system was validated by measuring open-ocean and coastal reference seawater, NASS-5 and CASS-4. Using the system with ICPMS analysis, we have obtained reliable trace metal concentrations in the water columns of the South China Sea. Possessing the features of full automation, high throughput, low blank, and low reagent volume used, the system automates and simplifies rigorous and complicated pretreatment procedures for multi-elemental analysis of trace metals in seawater and effectively enhances analytical capacity for trace metal analysis in environmental and seawater samples.     

Preconcentration of noble metals with the POLYORGS 4 complexing sorbent under the action of microwave irradiation

The sorption of Au(III), Pd(II), Pt(IV), Rh(III), and Ir(IV) with the POLYORGS 4 complexing sorbent in the static mode was studied at room temperature and on thermal and microwave heating. It was demonstrated that the sorption of noble metals from 1 M HCl and 1 M HNO₃ solutions can be substantially accelerated under the action of microwave irradiation. Based on the obtained data, the conditions of the group preconcentration of noble metals for their subsequent determination by the ETAAS and ICP AES methods were selected. The preconcentration procedure was used for the analysis of certified reference material SARM-7B (platinum-containing ore), VT-1 (copper-nickel sulfide ore), and the alloy of copper with noble metals.     

Novel phenyl-iminodiacetic acid grafted multiwalled carbon nanotubes for solid phase extraction of iron, copper and lead ions from aqueous medium

We have covalently grafted phenyl-iminodiacetic acid groups onto multi-walled carbon nanotubes via a diazotation reaction. The resulting material was characterized by FT-IR and UV–vis spectroscopy, by TGA, XPS and SEM. It is shown to be a valuable solid-phase extraction adsorbent for the preconcentration of trace quantities of Fe(III), Cu(II) and Pb(II) ion from aqueous solution prior to their determination by ICP-OES. Various factors affectting the separation and preconcentration were investigated. The enrichment factor typically is 100. Under optimized experimental conditions, the maximum adsorption capacities for Fe(III), Cu(II) and Pb (II) are 64.5, 30.5 and 17.0?mg?g-1, respectively, the detection limits are 0.26, 0.15 and 0.18?ng?mL-1, and the relative standard deviations are <2.5% (n?=?6). The new adsorbent shows superior reusability and stability. The procedure was successfully applied to the determination of trace quantities of Fe(III), Cu(II) and Pb (II) in water samples.

Simultaneous determination of seven metal ions in water samples by solid-phase extraction on polyacrylonitrile activated carbon fibres

A new solid-phase extraction method utilising polyacrylonitrile activated carbon fibres (PAN-ACFs) as adsorbent was developed for the preconcentration of trace metal ions prior to their determination by inductively coupled plasma optical emission spectrometry (ICP-OES). The PAN-ACFs oxidised with nitric acid were characterised by FT-IR, XRD, SEM and BET analysis. Then the resulting PAN-ACFs were used as solid-phase adsorbent for simultaneously determination of trace Al(III), Be(II), Bi(III), Cr(III), Cu(II), Fe(III) and Pb(II) ions in aqueous solutions. The influences of the analytical parameters on the recoveries of the studied ions were investigated. The optimum experimental conditions of the proposed method were pH: 6.0; eluent concentration and volume: 3.0 mL of 1.5 mol L^?1 nitric acid; flow rates of sample and eluent solution: 1.5 mL min^?1. The preconcentration factors were found to be 67 for Al(III), Bi(III); 83 for Cr(III), Cu(II), Fe(III) and 50 for Be(II), Pb(II). The precision of this method was in range of 1.5%~3.5% and the detection limit of this metal ions was between 0.06~1.50 μg L^?1. The developed method was validated by the analysis of a certified reference sample and successfully applied to the determination of trace metal ions in water samples with satisfactory results.     

Screening of dissolved heavy metals (Cu,Zn, Mn,Al, Cd,Ni, Pb) in seawater by a liquid-membrane–ICP–MS approach

A bulk liquid membrane system has been developed and applied to the simultaneous separation and preconcentration of up to seven heavy metals (copper, zinc, lead, cadmium, aluminium, manganese, and nickel) in seawater. Copper was selected to optimize transport conditions and then, under these conditions, the simultaneous extraction of other heavy metals was studied. The system achieved preconcentration yields ranging between 44.11% (Cd) and 77.77% (Cu) after nine hours of operation, the effectiveness of metal transport being Cu > Zn > Pb > Mn > Ni > Al > Cd. The system was applied to the preconcentration of four real seawater samples before their quantification by inductively coupled plasma–mass spectrometry (ICP–MS). Compared with the analytical procedures commonly used for trace metal determination in oceanography, the results obtained demonstrated that the new system may be used as a very clean (sample contamination-free), simple, and one-step alternative for semiquantitative, and even quantitative, simultaneous determination of heavy metals in seawater.     

Using silica modified by Tiron for metal preconcentration and determination in natural waters by inductively coupled plasma atomic emission spectrometry

A new adsorbent is synthesized on the basis of silica consecutively modified by polyhexamethylene guanidine and 4,5-dihydroxy-1,3-benzenedisulfonic acid (Tiron) for the group preconcentration of Fe(III), Al(III), Cu(II), Pb(II), Zn(II), and Mn(II) followed by determination by inductively coupled plasma atomic emission spectrometry. The adsorbent in the batch mode quantitatively (recovery 98?99%) extracts Fe(III), Al(III) and Cu(II) ions at pH 4.0 and Fe(III), Al(III), Cu(II), Pb(II), Zn(II), and Mn(II) ions at pH 7.0; the time of attainment of an adsorption equilibrium does not exceed 10 min. Consecutive preconcentration at pH 4.0 and 7.0 in the batch and dynamic modes ensures the quantitative separation of Fe(III), Al(III), and Cu(II) from Pb(II), Zn(II), and Mn(II) and their separate determination. The quantitative desorption of metals was attained with 0.5?1.0 M HNO₃ (5 or 10 mL). In preconcentration from 200 mL of solution with 5 mL of a desorbing solution, the preconcentration coefficient was equal to 40. The developed procedure was used for the determination of metal ions in river waters of Krasnoyarsk Krai. The results obtained were verified by the added?found method.     

Determination of gold,palladium and copper by flame atomic absorption spectrometry after preconcentration on silica gel modified with 3-(2-aminoethylamino)propyl group

A preconcentration method of gold, palladium and copper based on the sorption of Au (III), Pd (II) and Cu (II) ions on a column packed with 3-(2-aminoethylamino)propyl bonded silica gel is described. The modified silica gel was synthesized and characterized by FT-IR and C, H, N elemental analysis. At column preconcentration, the effects of parameters such as pH, volume, flow rate, matrix constituents of solutions and type of eluent on preconcentration of gold, palladium and copper were studied. The recoveries of Au (III), Pd (II) and Cu (II) were 98.93±0.51, 98.81±0.36 and 99.21±0.42 % at 95 % confidence level, respectively. The detection limits (δ) of the elements were 0.032, 0.016 and 0.012 μg ml⁻¹, respectively. The preconcentration method was applied for determination of gold and palladium in certified reference material SARM 7B and copper in river and synthetic seawater by FAAS. Gold, palladium and copper were determined with relative error lower than 10 %.     

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.     

Study on Preconcentration of Trace Copper Using Microcrystalline Triphenylmethane Loaded with Malachite Green

The paper describes a novel method for copper preconcentration using microcrystalline triphenylmethane loaded with malachite green prior to the determination by the flame atomic absorption spectrometry （FAAS）. Under the optimum conditions, Cu（Ⅱ） can be totally adsorbed on the surface of microcrystalline triphenylmethane, and completely separated from Pb（Ⅱ）, Cd（Ⅱ）, Co（Ⅱ）, Cr（Ⅲ）, Ni（Ⅱ）, Mn（Ⅱ）, Fe（Ⅲ） and Al（Ⅲ） by controlling acidity. The preconcentration factor of this proposed method is 200. The recovery is in a range of 97.5%-105%. The relative standard deviation （RSD） is not beyond 3.0%. The proposed method has been successfully applied to the determination of trace copper in various water samples with satisfactory results.