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1.
We report on the application of emulsification-based dispersive liquid microextraction (EB-DLME) to the preconcentration of Cd(II). This procedure not only possesses all the advantages of routine DLLME, but also results in a more stable cloudy state which is particularly useful when coupling it to FAAS. In EB-DLME, appropriate amounts of the extraction solvent (a solution of dithizone in chloroform) and an aqueous solution of sodium dodecyl sulfate (SDS; acting as a disperser) are injected into the samples. A stable cloudy microemulsion is formed and Cd(II) ion is extracted by chelation. After phase separation, the sedimented phase is subjected to FAAS. Under optimized conditions, the calibration curve for Cd(II) is linear in the range from 0.1 to 25 μg L?1, the limit of detection (at S/N?=?3) is 30 pg L?1, the relative standard deviations for seven replicate analyses (at 0.56 μg L?1 of Cd(II)) is 4.6 %, and the enrichment factor is 151. EB-DLME in our opinion is a simple, efficient and rapid method for the preconcentration of Cd(II) (and most likely of many other ions) prior to FAAS determination.
Figure
Emulsification based dispersive liquid microextraction is presented for determination of cadmium in water samples  相似文献   

2.
Multiwalled carbon nanotubes were grafted with tris(2-aminoethyl)amine (MWCNTs-TAA) and employed for solid phase extraction and preconcentration of trace lead ions prior to its determination by inductively coupled plasma optical emission spectrometry. The material was characterized by FT-IR and Raman spectroscopy, thermosgravimetric and elemental analysis. The effects of pH value, shaking time, sample volume, elution conditions and potentially interfering ions were investigated. Under the optimum conditions, the maximum adsorption capacity is 38?mg?g?1 of Pb(II), the detection limit is 0.32?ng?mL?1, the enrichment factor is 60, and the relative standard deviation is 3.5% (n?=?6). The method has been applied to the preconcentration of trace amounts of Pb(II) in environmental water samples with satisfactory results.
Figure
Oxidized multiwalled carbon nanotubes grafted with tris(2-aminoethyl)amine (MWCNTs-TAA) is prepared and employed as solid phase extraction sorbent to determinate the trace Pb(II) in water samples. The method has been applied to the preconcentration of trace amount of Pb(II) in water samples with satisfactory results.  相似文献   

3.
We have prepared the hydrophobic amino-functionalized ionic liquid (IL) 1-(2-aminoethyl)-3-butylimidazolium hexafluorophosphate and investigated its extraction behavior for copper(II) ion as a model cation. The IL, due to the presence of an amino group, is capable of complexing Cu(II) in a ratio of 6:1. The parameters affecting the extraction efficiency were optimized. The IL-based liquid–liquid microextraction was successfully applied to the analysis of Cu(II) in an environmental water standard reference material. The results are promising in terms of liquid–liquid microextraction, separation, and preconcentration of Cu(II).
Figure
A hydrophobic amino-functionalized ionic liquid (IL) [NH2C2C4im][PF6] was synthesized. The IL exhibits good extractability for copper (II) ion due to the presence of an amino group.  相似文献   

4.
We report on a novel and selective method for the preconcentration and determination of Cr(VI) in aqueous samples. Cr(VI) is adsorbed - in a “batch mode” - on multiwalled carbon nanotubes covered with Aliquat 336 and then determined directly, i.e., on the solid, by X-ray fluorescence spectrometry. This reduces the number of reagents and minimizes sample handling. The method combines the advantages of solid-phase extraction with the benefits of the XRF method in that the large areas required by the carbon nanotubes make them a promising solid sorbent for preconcentration. The enrichment factor was calculated after considering that the thin film obtained from the 10?mL solution of 1?mg?L?1 of Cr(VI) has a real thickness of 0.04?mm and a final diameter of 16.7?mm, so that the volume deposited on the pellet is 0.0088 cm3 and the preconcentration factor is 1000.
A novel and selective method for the preconcentration and determination of Cr(VI) in aqueous samples is proposed. Cr(VI) is adsorbed - in a “batch mode” - on multiwalled carbon nanotubes (MWCNTs) covered with Aliquat 336 and then determined directly, i.e., on the solid, by X-ray fluorescence spectrometry. This reduces the number of reagents and minimizes sample handling.  相似文献   

5.
A solid phase extraction method is presented for the selective preconcentration and/or separation of trace Pb(II) on multiwalled carbon nanotubes modified with 2-aminobenzothiazole. Inductively coupled plasma optical emission spectrometry was used for detection. The effects of pH, shaking time, sample flow rate and volume, elution condition and interfering ions were examined using batch and column procedures. An enrichment factor of 100 was accomplished. Common other ions do not interfere in both the separation and determination. The maximum adsorption capacity of the sorbent at optimum conditions is 60.3?mg?g?1 of Pb(II), the detection limit (3??) is 0.27?ng?mL?1, and the relative standard deviation is 1.6% (n?=?8). The method was validated using a certified reference material, and has been applied to the determination of trace Pb(II) in water samples with satisfactory results.
Figure
2-Aminobenzothiazole modified multiwalled carbon nanotubes has been developed to separate and concentrate trace Pb(II) from aqueous samples. Parameters that affect the sorption and elution efficiency were studied in batch and column modes, and the new sorbent (MWCNTs-ABTZ) presents high selectivity and adsorption capacity for the solid phase extraction of trace Pb(II).  相似文献   

6.
We report on a simple, rapid and efficient extraction procedure, referred to as ultrasound-assisted cold-induced aggregation (USA-CIAME), for the extraction of phenol from aqueous samples. In this method, very small amounts of the ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate (the extractant) are dissolved in a sample solution containing phenol and ultrasonicated for 1?min. The solution is cooled in an ice bath upon which a cloudy solution forms. Following centrifugation, the extractant phase settles at the bottom of a conical-bottom centrifuge tube. Phenol is photometrically determined after its chromogenic reaction with 4-aminoantipyrine in the presences of hexacyanoferrate at pH 10.0. Compared to the conventional cold-induced aggregation microextraction (CIAME) and dispersive liquid liquid microextraction (DLLME), the optimized approach displays the highest extraction efficiency at room temperature, and the shortest extraction time (5?min). Key parameters affecting the performance were evaluated and optimized. Under optimum conditions, the limit of detection of phenol is 0.86?μg?L?1, and the enrichment factor is 75. The calibration graph as linear over the range from 3 to 150?μg?L?1, and the relative standard deviation is 2.65% (n?=?5). The method was successfully applied to the determination of phenol in water samples.
Figure
Schematic representation Ultrasound assisted Cold- induced aggregation (USA-CIAME), which is effective sample pretreatment technique present large extraction efficiencies for the extraction and determination of volatile phenol from aqueous samples and represent a new platform for separation techniques.  相似文献   

7.
Cold-induced aggregation microextraction (CIAME) combined with flame atomic absorption spectrometry (FAAS) was applied to preconcentration and determination of nickel(II) ions in natural water samples. The proposed method used 1-hexyl-3-methylimidazolium hexafluorophosphate ([Hmim][PF 6 ]) as the extraction solvent and 1-(2-thiazolylazo)-2-naphthol (TAN) as the complexing agent. The extraction solvent was dissolved in the sample solution at 45°C. After dissolving, the solution was cooled in the ice bath and a cloudy solution of IL fine droplets was formed due to the decrease of IL solubility. After centrifugation, the fine droplets of extractant phase were settled at the bottom of the conical-bottom centrifuge tube. Analysis was carried out by a FAAS. Several important parameters influencing the CIAME extraction efficiency such as pH, complexing agent concentration, extraction solvent volume, salt effect, solution temperature, extraction time, centrifugation time and heating time were investigated and optimized. Under the optimum conditions, the limit of detection (LOD) was 0.8 ng/mL, and the relative standard deviation (RSD) was 3.4% for 50 ng/mL of nickel. The performance of the method was evaluated for extraction and determination of nickel in tap, mineral and seawater samples, and satisfactory results were obtained.  相似文献   

8.
A solid phase extraction method is presented for the preconcentration of trace lead ions on oxidized multiwalled carbon nanotubes (ox-MWCNTs). In the first step, the cationic Pb(II) complex of 2,2-bipyridyl is formed which, in a second step, is adsorbed on ox-MWCNTs mainly due to electrostatic and van der Waals interactions. The Pb(II) ions were then eluted with dilute nitric acid and quantified by FAAS. The effects of pH value, mass of sorbent, concentration of 2,2-bipyridyl, stirring time, of type, concentration and volume of eluent, of eluent flow rate and sample volume were examined. Most other ions do not affect the recovery of Pb(II). The limits of detection are 240 and 60 ng L?1 for sample volumes of 100 and 400 mL, respectively. The recovery and relative standard deviation are >95 % and 2.4 %, respectively. Other figures of merit include a preconcentration factor of 160 and a maximum adsorption capacity of 165 mg g?1. The method was successfully applied to the determination of Pb(II) in spiked tap water samples. The accuracy of the method was verified by correctly analyzing a certified reference material (NCS ZC85006; lead in tomatoes).
Figure
A solid phase extraction method is presented for the preconcentration of trace lead ions on oxidized multiwalled carbon nanotubes (ox-MWCNTs). Most other ions do not affect the recovery of Pb(II).  相似文献   

9.
Feng Pan  Jie Mao  Qiang Chen  Pengbo Wang 《Mikrochimica acta》2013,180(15-16):1471-1477
Magnetic Fe3O4@SiO2 core shell nanoparticles containing diphenylcarbazide in the shell were utilized for solid phase extraction of Hg(II) from aqueous solutions. The Hg(II) loaded nanoparticles were then separated by applying an external magnetic field. Adsorbed Hg(II) was desorbed and its concentration determined with a rhodamine-based fluorescent probe. The calibration graph for Hg(II) is linear in the 60 nM to 7.0 μM concentration range, and the detection limit is at 23 nM. The method was applied, with satisfying results, to the determination of Hg(II) in industrial waste water.
Figure
Functional magnetic Fe3O4@SiO2 core shell nanoparticles were utilized for solid phase extraction of Hg(II) from aqueous solutions, and the extracted Hg(II) was determined by a rhodamine-based fluorescent probe RP with satisfying results.  相似文献   

10.
Graphene nanosheets were modified with amino groups and the resulting material was used as a sorbent for the extraction of cadmium and lead ions. The nanosheets were characterized by IR spectroscopy, transmission electron microscopy, thermal gravimetric analysis and elemental analysis. The effects of sample pH, eluent parameters (type, concentration and volume of eluent), flow rates (of both sample and eluent), and of a variety of other ions on the efficiency of the extraction of Cd(II) and Pb(II) were optimized. Following solid phase extraction, the elements were determined by FAAS. The limits of detection are <0.9 μg L?1 for Pb(II) and <5 ng L?1 for Cd(II). The relative standard deviations are <2.2 %. The method was validated by analyzing several certified reference materials and was then used for Pb(II) and Cd(II) determination in natural waters and vegetables.
Figure
In this work, grapheme oxide nanosheets were modified with amino and tri-amino groups and their application were investigated in Cd(II) and Pb(II) determination in food sample. The results show high preconcentration factor and adsorption capacities for these nanosheets.  相似文献   

11.
We describe the application of temperature-controlled ionic liquid based microextraction (TC-IL-ME) of lead(II) ion. The method does not require the use of an organic solvent or a ligand. Rather, the IL is directly added to the aqueous sample containing Pb(II) in a centrifuge tube, and the mixture is heated to 80 °C for 4 min. After cooling at 0 °C, the solution turns cludy due to the formation of fine droplets of the IL containing Pb(II). The IL is separated by centrifugation, acidified, and directly submitted to FAAS by microinjection. The effects of pH value, volume of IL, extraction time, temperature, sample volume and matrix were optimized to result in a preconcentration factor of 30, a detection limit of 5.8 μg L?1, and a limit of quantification of 19.3 μg L?1. The method was validated by analyzing a certified reference material (NCSZC81002B; hair). A recovery test performed with spiked samples gave values between 102 % and 105 %. The method was also used to determine Pb(II) in hair samples.
Figure
We describe the application of temperature-controlled ionic liquid based microextraction (TC-IL-ME) of lead(II) ion. The effects of pH value, volume of IL, extraction time, temperature, sample volume and matrix were optimized.  相似文献   

12.
We describe a solid phase extractor for selective separation and preconcentration of Hg(II) ion. It was prepared by immobilizing the adduct of diethylenetriamine and thiourea on silica gel. The effects of solution acidity, preconcentration time, sample flow rate and volume were optimized. The results show that Hg(II) can be selectively extracted from acidic solutions and in presence of common other metal ions. The adsorbent is stable, can be reused more than 10 times, and the maximum adsorption capacity is 23 mg g?1. Hg(II) was quantified by inductively coupled plasma optical emission spectrometry. The method has a detection limit of 23 ng L?1, and the relative standard deviation is <2 %. The procedure was validated by analyzing two standard materials (river sediment and hair powder), and was successfully applied to the preconcentration of Hg(II) in real samples.
Figure
A solid phase extractor was firstly prepared by immobilizing DETA-TU (equimolar adduct of diethylenetriamine and thiourea) on the silica gel, which was applied to selectively separate/preconcentrate trace Hg(II) from real samples  相似文献   

13.
A new solid-phase extraction sorbent was used for the preconcentration of Pb(II) and Cr(III) ions prior to their determination by flame atomic absorption spectrometry. It was prepared by immobilization of 2,4-dinitrophenylhydrazine on nano-alumina coated with sodium dodecyl sulfate. The sorbent was characterized by scanning electron microscopy, N2 adsorption and Fourier transform infrared spectrometry, and used for preconcentration and separation of Pb(II) and Cr(III) from aqueous solutions. The ions on the sorbent were eluted with a mixture of nitric acid and methanol. The effects of sample pH, flow rates of samples and eluent, type of eluent, breakthrough volume and potentially interfering ions were studied. Linearity is maintained between 1.2 and 350???g?L-1 of Pb(II), and between 2.4 and 520???g?L-1 of Cr(III) for an 800-mL sample. The detection limit (3?s, N?=?10) for Pb(II) and Cr(III) ions is 0.43 and 0.55???g?L-1, respectively, and the maximum preconcentration factor is 267. The method was successfully applied to the evaluation of these trace and toxic metals in various water, food, industrial effluent and urine samples.
Figure
Recovery percentage of Pb(II) and Cr(III) ions at different solution volumes.  相似文献   

14.
We describe a nanosized Cd(II)-imprinted polymer that was prepared from 4-vinyl pyridine (the functional monomer), ethyleneglycol dimethacrylate (the cross-linker), 2,2′-azobisisobutyronitrile (the radical initiator), neocuproine (the ligand), and Cd(II) (the template ion) by precipitation polymerization in acetonitrile as the solvent. The imprinted polymer was characterized by X-ray diffraction, thermogravimetric analysis, differential thermal analysis, and scanning electron microscopy. The maximum adsorption capacity of the nanosized sorbent was calculated to be 64 mg g?1. Cadmium(II) was then quantified by FAAS. The relative standard deviation and limit of detection are 4.2 % and 0.2 μg L?1, respectively. The imprinted polymer displays improve selectivity for Cd(II) ions over a range of competing metal ions with the same charge and similar ionic radius. This nanosized sorbent is an efficient solid phase for selective extraction and preconcentration of Cd(II) in complex matrices. The method was successfully applied to the trace determination of Cd(II) in food and water samples.
Figure
We describe a nanosized ion-imprinted polymer (IIP) for the selective preconcentration of Cd(II) ions. The nanosized-IIP was characterized by X-ray diffraction, Fourier transform IR spectroscopy, thermogravimetric and differential thermal analysis, and by scanning electron microscopy.  相似文献   

15.
We describe a nanometer sized composite material made from titanium dioxide and silica that was chemically modified with 4-aminophenylarsonic acid and used for selective solid-phase extraction, separation and preconcentration of of aluminum(III) prior to its determination by ICP-OES. Under optimized conditions, the static adsorption capacity is 56.58?mg?g?1, the enrichment factor is 150, the relative standard deviation is 1.6% (for n?=?11), and the detection limit (3?s) is 60?pg?mL?1. The method was validated by analyzing the reference materials GBW 09101 (hair) and GBW 10024 (scallop) and successfully applied to the determination of trace Al(III) in spiked water samples and human urine, with recoveries ranging from 96% to 101%.
Figure
4-aminophenylarsonic acid modified nanometer TiO2/SiO2 composite material has been developed to separate and concentrate trace Al(III) from aqueous samples. Parameters that affect the sorption and elution efficiency were studied in column mode, and the new adsorbent presents high selectivity and adsorption capacity for the solid phase extraction of trace Al(III).  相似文献   

16.
We report on a new method for the microextraction and determination of zinc (II). The ion is accumulated via ionic-liquid cold-induced aggregation dispersive liquid-liquid microextraction (IL-CIA-DLLME) followed by flame atomic absorption spectrometry (FAAS). The ionic liquid (IL) 1-hexyl-3-methylimidazolium hexafluorophosphate is dispersed into a heated sample solution containing sodium hexafluorophosphate as a common ion source. The solution is then placed in an ice-water bath upon which a cloudy solution forms due to the decrease of the solubility of the IL. Zinc is complexed with 8-hydroxyquinoline and extracted into the IL. The enriched phase is dissolved in a diluting agent and introduced to the FAAS. The method is not influenced by variations in the ionic strength of the sample solution. Factors affecting the performance were evaluated and optimized. At optimum conditions, the limit of detection is 0.18???g?L?1, and the relative standard deviation is 3.0% (at n?=?5). The method was validated by recovery experiments and by analyzing a certified reference material and successfully applied to the determination of Zn (II) in water and food samples.
Figure
?  相似文献   

17.
We have developed a new method for solid phase extraction (SPE) and preconcentration of trace amounts of cadmium and zinc using cross linked chitosan that was functionalized with 2-aminopyridine-3-carboxy acid. Analytical parameters, sample pH, effect of flow rate, sample volume, and concentration of eluent on column SPE were investigated. The effect of matrix ions on the recovery of cadmium and zinc has been investigated and were found not to interfere with preconcentration. Under the optimum experimental conditions, the preconcentration factors for Cd(II) and Zn(II) were found to be 90. The two elements were quantified via atomic absorption spectrometry. The detection limits for cadmium and zinc are 21 and 65?ng?L?1, respectively. The method was evaluated by analyzing a certified reference material (NIST 1643e; water) and has been successfully applied to the analysis of cadmium and zinc in environmental water samples.
Figure
A simple and sensitive solid phase extraction method for the preconcentration of Cd(II) and Zn(II) in environmental samples using cross linked chitosan functionalized with 2-aminopyridine-3-carboxylic acid was developed. The metal ions enriched by functionalized chitosan were eluted with acid and determined by AAS.  相似文献   

18.
We have developed a modified method for the extraction and preconcentration of benzene, toluene, ethylbenzene and xylenes (BTEX) in aqueous samples. It based on dispersive liquid-liquid microextraction along with solidification of floating organic microdrops. The dispersion of microvolumes of an extracting solvent into the aqueous occurs without dispersive solvent. Various parameters have been optimized. BTEX were quantified via GC with FID detection. Under optimized conditions, the preconcentration factors range from 301 to 514, extraction efficiencies from 60 to 103 %, repeatabilities from 2.2 to 4.1 %, and intermediate precisions from 3.5 to 7.0 %. The relative recovery for each analyte in water samples at three spiking levels is >85.6 %, with a relative standard deviation of <7.4 %.
Figure
A modified method based on dispersive liquid-liquid microextraction to preconcentrate benzene, toluene, ethylbenzene and xylenes was investigated. The method was rapid, precise, efficient, and sensitive. Experimental parameters affecting the extraction process were evaluated. The optimized procedure was validated according to the ICH guidance.  相似文献   

19.
This review (160 refs). covers the current state of the art of microbacteria-based sorbents for preconcentration of metal ions at trace levels. We highlight advantages and major challenges of the techniques and discuss future perspectives of both batch and column-based methods. Particular attention is paid to the preconcentration of metal ions using resin-immobilized microbacteria for solid phase extractions. We also discuss detection methods including UV–vis spectrophotometry, FAAS, ICP-OES and ICP-MS. Analytical figures of merit are compared, and examples are given for the application to a variety of samples including food, beverages, alloys, water, soil, and geological samples.
Figure
An graphical presentation of main experimental steps in solid phase extraction procedure for metal ions together with the summarization of affinity of metal ions to functional groups on the surface of bacteria by considering the classifications according to hard and soft acids and bases theory by Pearson  相似文献   

20.
We describe a novel magnetic metal-organic framework (MOF) for the preconcentration of Cd(II) and Pb(II) ions. The MOF was prepared from the Fe3O4-pyridine conjugate and the copper(II) complex of trimesic acid. The MOF was characterized by IR spectroscopy, elemental analysis, SEM and XRD. A Box-Behnken design through response surface methodology and experimental design was used to identify the optimal parameters for preconcentration. Extraction time, amount of magnetic MOF and pH value were found to be critical factors for uptake, while type, volume, concentration of eluent, and elution time are critical in the elution step. The ions were then determined by FAAS. The limits of detection are 0.2 and 1.1 μg?L?1 for Cd(II), and Pb(II) ions, respectively, relative standard deviations are <4.5% (for five replicates at 50 μg?L?1 of Cd(II) and Pb(II) ions), and the enrichment capacity of the MOF is at around 190 mg?g?1 for both ions which is higher than the conventional Fe3O4-pyridine material. The magnetic MOF was successfully applied to the rapid extraction of trace quantities of Cd(II) and Pb(II) ions in fish, sediment, and water samples.
Figure
Schematic illustration of synthesized magnetic MOF-pyridine nanocomposite  相似文献   

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