巯基微球富集用于近红外光谱同时定量分析微量汞(Ⅱ)和银(Ⅰ)离子

针对近红外光谱技术的检出限高和金属离子在近红外区无信号响应的问题, 合成了巯基聚倍半硅氧烷微球(PMPSQ), 用以高效富集水溶液中的微量汞(Ⅱ)和银(Ⅰ)离子. 通过金属离子与巯基官能团螯合从而获得相应的近红外信号响应, 采集吸附了金属离子的PMPSQ的近红外漫反射光谱, 采用偏最小二乘法建立了定量校正模型. 结果表明, 采用巯基微球富集结合近红外光谱技术可以同时测定水中浓度分别为0.16~1.80 mg/L的汞(Ⅱ)离子和0.15~1.70 mg/L的银(Ⅰ)离子.     

An approach by using near-infrared diffuse reflectance spectroscopy and resin adsorption for the determination of copper, cobalt and nickel ions in dilute solution

Near-infrared spectroscopy (NIRS) has been proved to be a powerful analytical tool and used in various fields, it is seldom, however, used in the analysis of metal ions in solutions. A method for quantitative determination of metal ions in solution is developed by using resin adsorption and near-infrared diffuse reflectance spectroscopy (NIRDRS). The method makes use of the resin adsorption for gathering the analytes from a dilute solution, and then NIRDRS of the adsorbate is measured. Because both the information of the metal ions and their interaction with the functional group of resin can be reflected in the spectrum, quantitative determination is achieved by using multivariate calibration technique. Taking copper (Cu²⁺), cobalt (Co²⁺) and nickel (Ni²⁺) as the analyzing targets and D401 resin as the adsorbent, partial least squares (PLS) model is built from the NIRDRS of the adsorbates. The results show that the concentrations that can be quantitatively detected are as low as 1.00, 1.98 and 1.00 mg L⁻¹ for Cu²⁺, Co²⁺ and Ni²⁺, respectively, and the coexistent ions do not influence the determination.     

Graphene oxide-packed micro-column solid-phase extraction combined with flame atomic absorption spectrometry for determination of lead (II) and nickel (II) in water samples

A sensitive and simple method has been established for simultaneous preconcentration of trace amounts of Pb (II) and Ni (II) ions in water samples prior to their determination by flame atomic absorption spectrometry. This method was based on the using of a micro-column filled with graphene oxide as an adsorbent. The influences of various analytical parameters such as solution pH, adsorbent amount, eluent type and volume, flow rates of sample and eluent, and matrix ions on the recoveries of the metal ions were investigated. Using the optimum conditions, the calibration graphs were linear in the range of 7–260 and 5–85 μg L^?1 with detection limits (3S_b) of 2.1 and 1.4 μg L^?1 for lead and nickel ions, respectively. The relative standard deviation for 10 replicate determinations of 50 μg L^?1 of lead and nickel ions were 4.1% and 3.8%, respectively. The preconcentration factors were 102.5 and 95 for lead and nickel ions, respectively. The adsorption capacity of the adsorbent was also determined. The method was successfully applied to determine the trace amounts of Pb (II) and Ni (II) ions in real water samples. The validation of the method was also performed by the standard reference material.     

Preconcentration of metal ions on aluminum oxide modified with tiron

It is found that iron(III), titanium(IV), vanadium(V), copper(II), lead(II), and zinc(II) ions are adsorbed on aluminum oxide modified with Tiron. The adsorption of iron(III) is accompanied by the violet coloration of the adsorbent (560 nm), which indicates the formation of a 1: 2 complex on the adsorbent surface; copper forms a 1: 1 yellowish green complex (430 nm). The group preconcentration of metal ions on this adsorbent in a dynamic mode is possible; the preconcentration rate is 2.5 × 10³. The method for the determination of metal ions is proposed based on the adsorption recovery of the elements followed by the direct determination by X-ray fluorescence spectroscopy on the adsorbent surface.     

Silver modified magnetic carbon nanotubes composite as a selective solid phase extractor for preconcentration and determination of trace mercury ions in water solution

A magnetic composite of silver/iron oxides/carbon nanotubes (Ag/Fe₃O₄/CNTs) was synthesized and used as an adsorbent for the preconcentration of mercury ions in water solutions at room temperature (25°C) in this study. The silver nanoparticles were supported on the magnetic CNTs. The modification enabled the composite had not only a high adsorption capacity for mercury ions (Hg²⁺) but also the magnetic isolation properties. A fast, sensitive, and simple method was successfully developed for the preconcentration and determination of trace amount of Hg²⁺ in water using the synthesized nanocomposite as adsorbent. The mercury concentration was determined by an atomic fluorescence spectrometer (AFS). The experimental conditions such as pH value, extraction temperature, extraction time, sample volume, eluent composition and concentration, sorbent amount, and coexisting ions were investigated for the optimization. A 500 mL of sample volume resulted in a preconcentration factor of 125. When a 200 mL of sample was employed, the limit of detection for Hg²⁺ was as low as 0.03 ng mL^?1with relative standard deviation of 4.4% at 0.1 ng mL^?1 (n = 7). The ease of synthesis and separation, the good adsorption capacity, and the satisfactory recovery will possibly make the composite an attractive adsorbent for the preconcentration of ultratrace Hg²⁺ in waters.     

Preconcentration of trace nickel lons from aqueous solutions by using a new and low cost chelating polystyrene adsorbent

A simple and reliable method has been developed using chelating polymeric adsorbent (PSAHSB) to preconcentration of trace amount of Ni(II) ions from aqueous solutions under static loading conditions, and their determination by Ultraviolet and visible (UV–Vis) absorption spectroscopy. The influences of some analytical adsorption parameters, such as pH, temperature and contact time, the ionization constants of chelating groups in the adsorbent and desorption process were investigated. Maximum adsorption ≥98% was achieved at pH 3–7 after 20 min of contact time and the relative standard-deviation values were ≤5%. Adsorbed metal ions have been desorbed with 10 mL of 2 M HCl acid with the detection limit of 0.0157 μg m⁻¹. The Langmuir and Freundlich isotherm equations were used to describe adsorption behavior of the system at different temperatures. Kinetic and thermodynamic behavior of the adsorbent for Ni(II) ion preconcentration was also studied. The possible adsorption mechanism of Ni (II) ions onto modified adsorbent is also discussed. This method was applied efficiently to remove Ni (II) ions from environmental water samples.     

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).     

Determination of Bovine Hemoglobin by Near-Infrared Diffuse Reflectance Spectroscopy with Novel Adsorption Preconcentration

A method for the quantitative determination of bovine hemoglobin in dilute solution was developed using adsorption preconcentration and near-infrared diffuse reflectance spectroscopy. An adsorbent, designated as multicarbonyl polymer-grafted silica particles, was prepared for the preconcentration of bovine hemoglobin in dilute solution. Under neutral conditions, the adsorption efficiency exceeded 98% within 20?min. After the preconcentration of bovine hemoglobin on the adsorbent, the near-infrared spectrum was measured in diffuse reflectance mode and a partial least squares model was constructed for quantitative prediction. Samples were analyzed in the presence of amino acid, albumin bovine V, D-glucose, and metal ions as potential interferences. The results show that bovine hemoglobin was selectively determined. The correlation coefficient between the predicted concentrations and the reference values was 0.9911, and the recoveries were from 86.4 to 111.2% for validation samples with concentrations between 2.1 and 30.0?mg?L^?1. Therefore, the determination of bovine hemoglobin was achieved by near-infrared diffuse reflectance spectroscopy combined with preconcentration and chemometric modeling.     

Determination of trace cadmium in waters by flame atomic absorption spectrophotometry after preconcentration with 1-nitroso-2-naphthol-3,6-disulfonic acid on Ambersorb 572

A procedure for the determination of trace amount of cadmium after adsorption of its 1-nitroso-2-naphthol-3,6-disulfonic acid chelate on Ambersorb 572 has been proposed. This chelate is adsorbed on the adsorbent in the pH range 3-8 from large volumes of aqueous solution of water samples with a preconcentration factor of 200. After being sorbed, cadmium was eluted by 5 mL of 2.0 mol L(-1) nitric acid solution and determined directly by flame atomic absorption spectrophotometery (FAAS). The detection limit (3sigma) of cadmium was 0.32 microg L(-1). The precision of the proposed procedure, calculated as the relative standard deviation of recovery in sample solution (100 mL) containing 5 microg of cadmium was satisfactory (1.9%). The adsorption of cadmium onto adsorbent can formally be described by a Langmuir equation with a maximum adsorption capacity of 19.6 mg g(-1) and a binding constant of 6.5 x 10(-3) L mg(-1). Various parameters, such as the effect of pH and the interference of a number of metal ions on the determination of cadmium, have been studied in detail to optimize the conditions for the preconcentration and determination of cadmium in water samples. This procedure was applied to the determination of cadmium in tap and river water samples.     

New Application of Chemically Modified Multiwalled Carbon Nanotubes with Thiosemicarbazide as a Sorbent for Separation and Preconcentration of Trace Amounts of Co(II), Cd(II), Cu(II), and Zn(II) in Environmental and Biological Samples Prior to Determination by Flame Atomic Absorption Spectrometry

The present article reports the application of Thiosemicarbazide‐modified multiwalled carbon nanotubes (MWCNTs‐TSC) as a new, easily prepared selective and stable solid sorbent for the preconcentration of trace Co(II), Cd(II), Cu(II) and Zn(II) ions in aqueous solution prior to the determination by flame atomic absorption spectrometry. The studied metal ions can be adsorbed quantitatively on MMWNTs at pH 5.0 and then eluted completely with HNO₃ (1.5 mol L^?1) prior to their determination by flame atomic absorption spectrometry. The separation/preconcentration conditions of analytes were investigated, including the pH, the sample flow rate and volume, the elution condition and the interfering ions. The maximum adsorption capacity of the adsorbent at optimum conditions were found to be 32.5, 27.3, 44.5 and 34.1 mg g^?1 for Co(II), Cd(II), Cu(II) and Zn(II), and the detection limits of the method were found to be 0.28, 0.13, 0.21 and 0.17 μg L^?1, respectively. The proposed method was successfully applied for extraction and determination of the analytes in well water, sea water, wastewater, soil, and blood samples.     

Nanometer-sized alumina coated with chromotropic acid as solid phase metal extractant from environmental samples and determination by inductively coupled plasma atomic emission spectrometry

A method for solid phase extraction of trace metals such as Cd²⁺, Cr⁶⁺, Cu²⁺, Fe³⁺, Mn²⁺, Ni²⁺, Pb²⁺ and Zn²⁺ using nanometer-sized alumina coated with chromotropic acid prior to determination by inductively coupled plasma atomic emission spectrometry (ICP-AES) has been developed. Various influencing parameters on the separation and preconcentration of trace metals, pH, flow rate, sample volume, amount of adsorbent, concentration of eluent and sorption kinetics have been studied. The detection limits for Cd²⁺, Cr⁶⁺, Cu²⁺, Fe³⁺, Mn²⁺, Ni²⁺, Pb²⁺ and Zn²⁺ were found to be 0.14, 0.62, 0.22, 0.54, 0.27, 0.28, 0.53 and 0.38 ng ml^− 1, respectively. The adsorption capacity of the solid phase adsorption material is 10.3, 11.3, 14.5, 16.4, 15.1, 11.7, 15.4 and 16.8 mg g^− 1 for Cd²⁺, Cr⁶⁺, Cu²⁺, Fe³⁺, Mn²⁺, Ni^2+, Pb²⁺ and Zn²⁺, respectively. The preconcentration factor was obtained in the range of 50-100 for all studied metal ions. Coexisting ions over a high concentration range have not shown any significant effects on the determination of aforesaid metal ions. The accuracy of the proposed method was tested by standard reference materials (NIST 1643e: water, NIST 1573a: tomato leaves and NIST 1568a rice flour) and natural waters and the results obtained were in good agreement with the certified values.     

Novel Chelating Resin for Solid-Phase Extraction of Metals in Certified Reference Materials and Waters

A new chelating resin, poly(diacetonitrile methacrylamide-co-divinylbenzene-co-vinylimidazole), was synthesized and characterized by infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, and elemental analysis. The novel resin was used for the first time as a chelating adsorbent for the preconcentration of Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn from various samples by flame atomic absorption spectrometry. The adsorption capacities of the resin were 29.3, 31.6, 29.3, 27.3, 35.5, 31.7, 39.8, and 32.3?mg?g^?1 for Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn, respectively. The detection limits of the metal ions were from 0.42 to 3.21?µg?L^?1. A preconcentration factor of 30 for all metal ions was obtained. The precision of the method as the relative standard deviation was less than or equal to 2.6%. The described method was validated with certified reference materials and fortified real samples. The method was used for the determination of the analytes in well water and wastewater.     

Speciation of ultra-trace amounts of inorganic arsenic in water and rice samples by electrothermal atomic absorption spectrometry after solid-phase extraction with modified Fe3O4 nanoparticles

A new magnetic adsorbent, 3-mercaptopropionic acid coated 3-aminopropyl triethoxysilane modified Fe₃O₄ nanoparticle, was synthesised and used for the extraction and preconcentration of arsenic ions in aqueous solutions followed by electrothermal atomic absorption spectrometric determination. The adsorbent was characterised by TEM, SEM, XRD and FT-IR techniques and the method used the unique properties of magnetic nanoparticles, namely, high surface area and superparamagnetism which gave it the advantages of high extraction capacity, fast separation and low adsorbent consumption. Different parameters affecting extraction efficiency of the analyte including pH value, sample volume, adsorbent amount, extraction time and desorption conditions were investigated and optimised. Under the optimum conditions, wide linear range of 30–25,000 ng L^?1 and low detection limit of 10 ng L^?1 were obtained. The interday and intraday precisions (as RSD%) for five replicates determination of 50 and 25,000 ng L^?1 of arsenic ions were in the range of 2.3–3.2%. Furthermore, no significant interference was observed in the presence of coexisting ions and high preconcentration factor of 198 was obtained. The adsorption isotherm followed Langmuir model and its kinetic was second-order. The accuracy of the method was validated by analysing certi?ed reference materials for water and rice with satisfactory recoveries. Finally, the proposed method was successfully applied for the determination of ultra-trace amounts of arsenic in rice and water samples.     

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.     

Mesoporous titanium dioxide as a novel solid-phase extraction material for flow injection micro-column preconcentration on-line coupled with ICP-OES determination of trace metals in environmental samples

Mesoporous titanium dioxide as a novel solid-phase extraction material for flow injection micro-column preconcentration on-line coupled with ICP-OES determination of trace metals (Co, Cd, Cr, Cu, Mn, Ni, V, Ce, Dy, Eu, La and Yb) in environmental samples was described. Possessing a high adsorption capacity towards the metal ions, mesoporous titanium dioxide has found to be of great potential as an adsorbent for the preconcentration of trace metal ions in samples with complicated matrix. The experimental parameters including pH, sample flow rate, volume, elution and interfering ions on the recovery of the target analytes were investigated, and the optimal experimental conditions were established. Under the optimized operating conditions, a preconcentration time of 90 s and elution time of 18 s with enrichment factor of 10 and sampling frequency of 20 h⁻¹ were obtained. The detection limits of this method for the target elements were between 0.03 and 0.36 μg L⁻¹, and the relative standard deviations (R.S.D.s) were found to be less than 6.0% (n =7, c =5 ng mL⁻¹). The proposed method was validated using a certified reference material, and has been successfully applied for the determination of the afore mentioned trace metals in natural water samples and coal fly ash with satisfactory results.     

Development of an Efficient Procedure for Determination of Copper,Zinc and Iron after Solid Phase Extraction on 3‐(1‐(1‐H‐Indol‐3‐yl)‐3‐Phenylallyl)‐1H‐Indole Loaded on Duolite XAD 761

A method for the simultaneous preconcentration of Cu²⁺,Zn²⁺ and Fe³⁺ ions, in some food samples has been reported. The method is based on the adsorption of 3‐(1‐(1‐H‐indol‐3‐yl)‐3‐phenylallyl)‐1H‐indole (IPAI) loaded on Duolite XAD 761. The metal ions adsorbed on the modified solid phase resin are eluted using 6 mL of 4 mol L^?1 nitric acid. The influences of the analytical parameters including pH and amount of ligand and solid phase and type and amount of surfactant and sample volume on the metal ions recoveries were investigated. The effects of matrix ions on the retentions of the analytes were also examined. The recoveries of analytes were generally higher than 95% with a RSD lower than 5%. The method has been successfully applied for these metals content evaluation in some real samples.     

Preparation of L-asparagine complex of technetium-99m

Attempts have been made to employ magnesium oxide as the preconcentration agent for determination of trace metal sin seawater by neutron activation analysis. Hydrous magnesium oxide can efficienthy adsorb most cationic transition metals and rare earths in a simple water system. The adsorption behavior is believed to depend mainly from the association of the cationic species of the metals with MgO ₂ ^2– adsorbent. In seawater matrix some of the metal ions such as Hg²⁺, Ni²⁺, etc. may become inefficiently adsorbed owing to the formation of highly stable metal-chloro complexes with chloride ion. Usually the adsorption efficiencies of the metals can be recovered to be as high as the case in the simple water system if an acidified seawater (to pH1) is subjected to the adsorption experiment. In practice, a large volume of seawater (5 1) is stirred with a small amount of hydrous MgO (1 g). Thereafter, the trace metals adsorbed MgO is separated and taken to be neutron activated. The abundant sodium ion and ubiquitous bromide ion can be obviated by the adsorption process, thereby beneficial to the -spectrometry of the metals enriched on MgO.     

Simultaneous voltammetric analysis of lead,copper and mercury ions by carbon paste electrode based on 1-(3-aminopropyl) imidazole modified polymer

In this study, a carbon paste electrode modified with a novel 1-(3-aminopropyl) imidazole functionalised crosslinked chlorosulfonated poly(styrene)-divinyl benzene polymer was used for selective and sensitive determination of the trace amounts of Pb²⁺, Cu²⁺ and Hg²⁺ ions by square wave anodic stripping voltammetry. The effect of some parameters such as paste composition, pH, preconcentration time, reduction potential and time, type of supporting electrolyte and potential scan rate on the determination of metal ions were investigated to find the optimal conditions. The effective open-circuit accumulation of the studied metal ions was succeeded only by the modification of the carbon paste electrode with functional polymer. For 6 min open-circuit preconcentration, the detection limit of Pb²⁺, Cu²⁺ and Hg²⁺ was found to be 5, 9 and 14 µgL^?1, respectively at 100 mVs^?1. The results confirmed that the lower concentration levels of these trace metal ions can be determined with the increase of preconcentration time and/or potential scan rate. Good detection limits and large dynamic concentration ranges were also obtained for their binary and ternary mixtures. The optimised method was successively applied to determine the concentration of Pb²⁺, Cu²⁺ ions in the tap water sample and Cu²⁺ ion in the waste water sample in the presence of possible interfering species (RSD<1%, recoveries 96–110% for 4 min preconcentration).     

Simultaneous determination of metal ions as complexes of pentamethylene dithiocarbamate in Indus river water,Pakistan

River water samples before and after mixing with industrial effluents were collected at an interval of 4 weeks for one year and analyzed for simultaneous determination of Fe³⁺, Cr³⁺, Mn²⁺, Cu²⁺, Ni²⁺and Co²⁺ after preconcentration using pentamethylene dithiocarbamate (PMDTC) as derivatizing reagent and subsequent solvent extraction by high performance liquid chromatography (HPLC). The average levels (n = 12) of metal ions were found in the range of 14.2–542 μg/L. The results were then compared with a standard flame atomic absorption spectrophotometric method revealed no significant differences.     

Modified nanoalumina sorbent for sensitive trace cobalt determination in environmental and food samples by flame atomic absorption spectrometry

1-(2-pryidylazo)-2-naphthol (PAN) immobilized on sodium dodecyl sulfate-coated nano alumina was developed for the preconcentration and determination of metal cations Co (II) from environmental and food samples. The research results displayed that adsorbent has the highest adsorption capacity for Co (II) in this system. Desorption by elution of the adsorbent with 2.0?ml of a mixture of nitric acid and ethanol was carried out. After phase separation, the enriched analyte in the final solution is determined by flame atomic absorption spectrometry (FAAS) by using a micro sample introduction system. Analytical influencing parameters including pH value, amount of sorbent, equilibrium time, sample volume, volume and concentration of eluent were examined. The effect of common matrix ions has also been investigated and it was found that they had no influence on cobalt preconcentration. Under the optimum experimental conditions, the maximum capacity of sorbent was obtained as 20?mg?g^?1. The preconcentration factor and limit of detection were found to be 250 and 0.15?µg?L^?1, respectively. This method showed good precision with the relative standard deviation (RSD) of 2.4% and 2.1% in concentrations of 20 and 50?µg?L^?1, respectively. The accuracy of the method was evaluated by comparison of results with those obtained by electrothermal atomic absorption spectrometry. This method was successfully applied for preconcentration and determination of Co (II) in environmental and food samples.