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1.
 Acid Red 88 is strongly extracted by chloroform solutions of Aliquat 336 by an ion exchange mechanism and for its reextraction from the ion pair formed, relatively high concentrations of mineral acids are required. By impregnation of silica with the ion pairs between the cation of Aliquat 336 and the anion of the dye a chelating sorbent for metal ions can be obtained. The sorbent prepared may be successfully used for separation of mixtures of various metal ions by the column extraction chromatography technique, additional purification of sodium and potassium salts from ions of heavy metals and for concentration of trace amounts of ions of various metals from aqueous solutions followed by their quantitative determination. The sorbent can be used repeatedly in the process of sorption and desorption of metal ions (especially those forming less stable complexes with the reagent) after regeneration with solutions of perchloric acid. Received January 28, 1998. Revision March 1, 1999.  相似文献   

2.
 Two new chelating sorbents for metal ions were prepared by the impregnation of chemically modified silicas LiChroprep RP-8 and RP-18 with ion pairs composed of the cation of Aliquat 336 and the anion of Calcon. The sorbents were compared with an analogous sorbent with a plain silica carrier containing the same ion pairs. A hypothesis for binding this ion pair by the surfaces of the applied carriers was presented. A higher stability of the two sorbents in comparison with that of the plain silica chelating sorbent was demonstrated. The sorbents obtained were applied for chromatographic separations of some chosen mixtures of some metal ions and for additional purification of aqueous solutions of alkali metals from trace amounts of heavy metals. The multiple use of the sorbents based on RP-8 and RP-18 in sorption–desorption processes of metal ions without deterioration of their sorption capacities was demonstrated. Received March 8, 2000. Revision March 5, 2001.  相似文献   

3.
Graphene oxide (GO) is a novel material with excellent adsorptive properties. However, the very small particles of GO can cause serious problems is solid-phase extraction (SPE) such as the high pressure in SPE system and the adsorbent loss through pores of frit. These problems can be overcome by covalently binding GO nanosheets to a support. In this paper, GO was covalently bonded to spherical silica by coupling the amino groups of spherical aminosilica and the carboxyl groups of GO (GO@SiO2). The successful immobilization of GO nanosheets on the aminosilica was confirmed by scanning electron microscopy and X-ray photoelectron spectroscopy. The spherical particle covered by GO with crumpled silk wave-like carbon sheets are an ideal sorbent for SPE of metal ions. The wrinkled structure of the coating results in large surface area and a high extractive capacity. The adsorption bath experiment shows that Cu(II) and Pb(II) can be quantitatively adsorbed at pH 5.5 with maximum adsorption capacity of 6.0 and 13.6 mg g−1, respectively. Such features of GO nanosheets as softness and flexibility allow achieving excellent contact with analyzed solution in flow-rate conditions. In consequence, the metal ions can be quantitatively preconcentrated from high volume of aqueous samples with excellent flow-rate. SPE column is very stable and several adsorption–elution cycles can be performed without any loss of adsorptive properties. The GO@SiO2 was used for analysis of various water samples by flame atomic absorption spectrometry with excellent enrichment factors (200–250) and detection limits (0.084 and 0.27 ng mL−1 for Cu(II) and Pb(II), respectively).  相似文献   

4.
A novel dual-syringe flow injection (DSFI) on-line column preconcentration system coupled to flame atomic absorption spectrometry (FAAS) has been developed for automatic trace metal determination in natural waters and biological samples. The proposed method was based on the on-line retention of Cd(II), Pb(II), Cu(II), Co(II) and Ni(II) ions onto the surface of a strong cation exchanger resin named HyperSepSCX, in a readily exchangeable micro-cartridge format and subsequent elution with HCl (2?mol?L?1) prior to flame atomization. The sorbent and the micro-cartridge exhibited high long term chemical and mechanical stability with fast kinetics for all analytes. All main chemical and hydrodynamic factors affecting the performance of the proposed method were studied thoroughly. For 15.0?mL sample volume, the enhancement factors were calculated as 92, 97, 93, 99 and 77 for Cd(II), Pb(II), Cu(II), Co(II) and Ni(II) respectively and the detection limits (3?s) were in the range between 0.14 and 2.1?µg?L?1. The precision (RSD) obtained was lower than 3.3% for all five metal ions with a sample throughput of 12?h?1. The developed method was evaluated by analyzing certified reference materials and spiked environmental natural water samples.  相似文献   

5.
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.  相似文献   

6.
In this work, multiwalled carbon nanotubes were reacted with N‐[3‐(triet‐hoxysilyl)propyl]isonicotinamide to prepare pyridine‐functionalized carbon nanotubes. This novel sorbent was characterized by infrared spectroscopy, thermal and elemental analysis, and scanning electron microscopy. Functionalized carbon nanotubes were applied for the preconcentration and determination of copper ions using flame atomic absorption spectrometry. Various parameters such as sample pH, flow rate, eluent type and concentration, and its volume were optimized. Under optimal experimental conditions, the limit of detection, the relative standard deviation, and the recovery of the method were 0.65 ng/mL, 3.2% and 99.4%, respectively. After validating the method using standard reference materials, the new sorbent was applied for the extraction and determination of trace copper(II) ions in fruit samples.  相似文献   

7.
Summary The influence of acetonitrile, methanol and isopropanol as retention selectivily modifiers in reversed phase liquid chromatography on a poly(styrene-divinylbenzene) macroporous polymer sorbent (PLRP-S) is evaluated using the solvation parameter model. Retention results from a combination of adsorption and partitioning and is influenced by the equilibrium absorption of organic solvent by the polymer from the mobile phase. The sorption of solutes is dominated by the ease of cavity formation in or on the solvated sorbent, with a small contribution from lone pair-lone pair electron interactions. All polar interactions, such as dipole-type and hydrogenbond formation, are more favorable in the mobile phase and reduce retention. Changes in the uptake of organic solvent from the mobile phase affect kinetic properties of the column such as band broadening and porosity as well as retention. The PLRP-S solvated sorbent is suitable for solid-phase extraction and is more retentive than typical silica-based, bonded phase sorbents for extraction from water. As a surrogate system for estimating solute lipophilicity and biological activity through retention-property correlations it provides a poor fit for hydrogen-bond acid solutes and is too dipolar/polarizable to fit some models.  相似文献   

8.
Mapolelo M  Torto N  Prior B 《Talanta》2005,65(4):930-937
Sorption properties of six yeast strains were evaluated for trace enrichment of metal ions; Cd2+, Cr3+, Cr6+, Cu2+, Pb2+, and Zn2+ from aqueous environments. Metal concentration was determined by flame atomic absorption spectrometry (FAAS). The results showed that trace enrichment of the metals under study with yeast, was dependent on the pH and available metal ions. Enrichment time of 30 min gave an optimum metal uptake. The presence of Na+, K+, and Ca2+ suppressed the uptake of Pb by less than 5%, but suppressed the uptake of Zn by between 15 and 25%. Mg2+, Cu+, Cu2+, Cr3+ Cr6+, Cd2+, and Zn2+ suppressed the uptake of Pb by between 25 and 35%, and that of Zn by between 15 and 25%. For both Pb and Zn, Cd had the highest suppression of 35 and 30%, respectively for baker's yeast (Saccharomyces cerevisiae). Baker's yeast achieved enrichment factors (EF) of 23, 4, 100, and 1 for dam water, stream water, treated wastewater, and industrial effluent samples for Cu, Pb, Zn, and Cr, respectively. The recoveries of optimised Cd and Cr samples spiked with 2 μg ml−1 of the metal could reach up to 90%, but never exceeded 66% for 10 μg ml−1 samples. For Cu and Pb, the recoveries generally increased independent of concentration, however they were not as high as those for Zn, which exceeded 90% for all the samples spiked with 10 μg ml−1 of the metal. S. cerevisiae PR 61/3 had the highest EF for Cr as compared to the other yeast strains. S. cerevisiae PRI 60/78 was the only yeast strain which was able to enrich Cd in all the samples. Baker's yeast had the highest EFs for Cu and Zn as compared to the other yeast strains without pH adjustment of the water samples. Candida tropicalis attained the highest EFs for Pb as compared to the other yeast strains. The results indicate that all the yeast strains used had a high affinity for Zn based on the EF values achieved. The results from these studies demonstrate that yeast is a viable trace metal enrichment agent that can be used freely suspended in solution to enrich metal ions at relatively low concentrations. This has ramifications on the traditional methods of sampling, sample collection, and transportation from remote sampling sites.  相似文献   

9.
A new chelating sorbent for metal ions was prepared by modification of chemically modified silica – LiChroprep-NH2 with Calcon. The molecular mechanism of binding this reagent to the surface of the applied carrier is presented. The properties of this sorbent were compared to analogous sorbents with a plain silica carrier and chemically modified silicas – LiChroprep-RP containing Calcon. The advantages of the new sorbent compared to the silica and LiChroprep-RP chelating sorbents are demonstrated. The sorbent obtained was applied as stationary phase in solid-phase extraction (SPE) for separations of some chosen mixtures of metal ions and for additional purification of aqueous solutions of salts of alkali metals from trace amounts of heavy metals. The multiple use of the sorbent based on LiChroprep-NH2 in sorption-desorption processes of metal ions without deterioration of its sorption capacity is demonstrated.  相似文献   

10.
A pyrrole-based conductive polymer was prepared and applied as new sorbent for on-line solid-phase extraction (SPE) of phenol and chlorophenols from water samples. Polypyrrole (PPy) was synthesized by chemical oxidation of the monomer in non-aqueous solution. The efficiency of this polymer for extraction of phenol and chlorophenols was evaluated using 35 mg of PPy as the sorbent in an on-line SPE system coupled to reversed-phase liquid chromatography with UV detection. The mobile phase were mixture of phosphate buffer-acetonitrile and compounds were eluted by the mobile phase using a six-port switching valve. High volumes of water, up to 160 ml, could be preconcentrated without the loss of phenols, except for the more polar ones. The R.S.D. for a river water sample spiked with phenol and chlorophenols at sub-ppb level was lower than 7% (n=5) and detection limits of 15-100 and 35-150 ng l−1 for tap and river water were obtained, respectively.  相似文献   

11.
ABSTRACT

In this paper, a novel, simple, selective and effective solid phase extraction method based on ion-imprinted polymer (IIP) technology and flame atomic absorption spectrometry (FAAS) for separation and pre-concentration of trace amounts of titanium (IV) ions was reportd?. It was obtained by precipitation polymerisation by using 2-(2,4-dihydroxyphenyl)-3,5,7-trihydroxychromen-4-one titanium (IV) complex abbrivated as Ti(IV)-(morin), as the template molecule. After polymerisation, leaching the polymer in HNO3 (50% (v/v) solution caused formation cavities in the polymer. Characterisation studies of the ?Ti(IV)-imprinted polymer (Ti-IP) was performed by FT-IR, UV-Vis and scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDS) techniques and then, the effective factors on extraction were optimised. A sensitive response to Ti(IV) within a concentration range between 0.01 and 4.0 μg mL?1 was achieved under the optimum conditions. A total of 10.0 ng mL?1 and 80.0 mg g?1 were obtained as limit of detection (LOD, 3Sb/m) and maximum adsorption capacity, respectively. The relative standard deviation (RSD) for eight replicates detections of 0.2 μg mL?1 of Ti(IV)? was found to be 2.8%. By this method, pre-concentration factor (PF) of 100 was obtained. Successfully applying this method in the water and standard samples, reasonable results were obtained for the extraction and pre-concentration of the titanium ions.  相似文献   

12.
The efficiencies and performances of silver nanoparticle loaded activated carbon modified with 2-(4-isopropylbenzylideneamino)thiophenol (IPBATP-Ag-NP-AC) and activated carbon modified with IPBATP (IPBATP-AC), as new sorbents, were evaluated for separation and preconcentration of Cu2+, Zn2+, Co2+, Cd2+ and Pb2+ ions from real environmental samples. The retained metals content was reversibly eluted using 5?mL of CH3COOH (6.0?mol?L?1) and/or 10?mL of 4.0?mol?L?1 HNO3 for IPBATP-Ag-NP-AC and IPBATP-AC, respectively. The experimental parameters influence the recoveries of metal ions including pH, amounts of ligand and supports, condition of eluents, sample and eluent flow rates of has been investigated. The preconcentration factors were found to be 100 for Zn2+, Cd2+, Co2+, Cu2+ and 50 for Pb2+ ions using IPBATP-Ag-NP-AC, and 50 for Zn2+, Cd2+, Co2+, Cu2+ and 25 for Pb2+ ions using IPBATP-AC. The detection limit of both SPE-based sorbents was between 1.6–2.5?ng?mL?1 for IPBATP-AC and 1.3–2.5?ng?mL?1 for IPBATP-Ag-NP-AC. The proposed methods have been successfully applied for the extraction and determination of the understudy metal ions content in some real samples with extraction efficiencies higher than 90% and relative standard deviations (RSD) lower than 2.4%.  相似文献   

13.
Zhou YY  Wang SW  Kim KN  Li JH  Yan XP 《Talanta》2006,69(4):970-975
Dichlorodiphenyltrichloroethane (DDT) and its metabolites are a typical kind of persistent organic pollutants (POPs). Development of a simple, cost-effective and sensitive methodology to monitor DDTs concentrations in water environment is of particular significance for understanding the fate and behavior of these pollutants. In this paper, a method on the basis of solid-phase extraction (SPE) using expanded graphite (EG) as sorbent coupled on-line with high performance liquid chromatography (HPLC) was developed for the determination of trace levels of p,p′-DDD (2,2-bis(4-chlorophenyl)-1,1-dichloroethane), p,p′-DDT, o,p′-DDT and p,p′-DDE (2,2-bis(4-chlorophenyl)-1,1-dichloroethene) in water. The analytes in water were preconcentrated onto the SPE column packed with expanded graphite, and subsequently eluted with methanol-water (90:10) mixed solvent. HPLC with a photodiode array detector was used for their separation and detection. The developed on-line solid-phase extraction protocol for HPLC permits the current HPLC separation and the next preconcentration proceeded in parallel, and thus allows one determination within 8 min. The precision (R.S.D.) for 10 replicate injections of a mixture of 1 μg l−1 of each analyte was 3.2-6.2% for the peak area measurement. The detection limits (S/N = 3) for preconcentrating 50 ml of sample solution ranged from 10 to 25 ng l−1 at a sample throughput of 7.5 samples h−1. The enhancement factors were about 700. The method was applied to the determination of trace p,p′-DDD, p,p′-DDT, o,p′-DDT and p,p′-DDE in local lake, river and tap water samples.  相似文献   

14.
<正>Triacontyl modified silica gel as a sorbent coupled with gas chromatography-mass spectrometry(GC-MS) was developed to determine EPA prior 16 polycyclic aromatic hydrocarbons(PAHs) in water samples.Various parameters of solid-phase extraction such as organic modifier solvent,eluent,sample flow rate and volume were optimized.The developed method was found to yield a linear calibration curve in the concentration range of 0.05-8μg/L with respect to naphthalene,acenaphthylene,acenaphthene and 0.01-8μg/L for dibenz[a,h]anthracene and 0.05-14μg/L for fluorene,phenanthrene,anthracene and 0.01-14μg/L for the rest of analytes.Furthermore,the good accuracy and repeatability of the method made sure the requirements for achieving reliable analysis of PAHs in the environmental water samples,and the recoveries of optimal method were in the range of 80-120%except to higher volatility PAHs.C_(30)-bonded silica was proved to be an efficient sorbent for extraction of high molecular weight PAHs.  相似文献   

15.
16.
Nowadays there are limited types of commercially available stationary phases for hydrophilic interaction liquid chromatography and therefore new ones with unique selectivity are urgently in demand to meet the need of separations of various polar and hydrophilic analytes. The present study describes the preparation and evaluation of a new stationary phase based on thiourea derivative modified silica for hydrophilic interaction liquid chromatography. Thiourea derivative was bonded onto the surface of silica particles via a mild addition reaction between –NH2 and –SCN, and the result of elemental analysis together with infrared analysis and solid‐state NMR spectroscopy proved that the synthesis method was feasible. The new stationary phase succeeded in fast separations of a wide range of polar and hydrophilic analytes and exhibited excellent separation performance, especially unique selectivity. Furthermore, the effects of water content, buffer pH, and salt concentration on retention indicated that a complicated separation mechanism rather than partitioning was involved in the stationary phase and hydrogen bonding interaction between analytes and thiourea functional group could play a very important role in its selectivity. For sure, the new stationary phase is of a great potential as a new type of hydrophilic interaction liquid chromatographic stationary phase.  相似文献   

17.
Morin was successful as a chemical modifier to improve the reactivity of the nanometer SiO2 surface in terms of selective binding and extraction of heavy metal ions. This new functionalized nanometer SiO2 (nanometer SiO2-morin) was used as an effective sorbent for the solid-phase extraction (SPE) of Cd(II), Cu(II), Ni(II), Pb(II), Zn(II) in solutions prior to its determination by inductively coupled plasma atomic emission spectrometry (ICP-AES). Experimental conditions for effective adsorption of trace levels of metal ions were optimized with respect to different experimental parameters using static and dynamic procedures in detail. The pH 4.0 was chosen as the optimum pH value for the separation of metal ions on the newly sorbent. Complete elution of the adsorbed metal ions from the nanometer SiO2-morin was carried out using 2.0 mL of 0.5 mol L−1 of HCl. Common coexisting ions did not interfere with the separation and determination at pH 4.0. The maximum static adsorption capacity of the sorbent at optimum conditions was found to be 22.36, 36.8, 40.37, 33.21 and 25.99 mg metal/g SiO2-morin for Cd(II), Cu(II), Ni(II), Pb(II) and Zn(II), respectively. The time for 95% sorption for Cu(II) and Ni(II) and 70% sorption for Cd(II), Pb(II) and Zn(II) was less than 2 min. The relative standard deviation (RSD) of the method under optimum conditions was lower than 5.0% (n = 11). The procedure was validated by analyzing the certified reference river sediment material (GBW 08301, China), the results obtained were in good agreement with standard values. The nanometer SiO2-morin was successfully employed in the separation and preconcentration of trace Cd(II), Cu(II), Ni(II), Pb(II) and Zn(II) from the biological and natural water samples yielding 75-folds concentration factor.  相似文献   

18.
The behavior of acids (citric acid, nitric acid, oxalic acid, tartaric acid) as a mobile phase and imidazolium ionic liquids (the bromides, tetrafluoroborates and hexafluorophosphates of 1‐ethyl, 1‐butyl, and 1‐hexyl‐3‐methylimidazolium) as additives in ion exchange chromatography for cations (Na+, K+, Mg2+, Ca2+) separation were studied. The results showed that nitric acid and 1‐hexyl‐3‐methyl‐imidazolium hexafluorophosphate offered the most interesting features in the separation of cations, such as lower retention time and better resolution. The selected optimal conditions were achieved by adding 0.10 mM 1‐hexyl‐3‐methyl‐imidazolium hexafluorophosphate in 4.0 mM HNO3 mobile phase for the separation of four cations with the flow rate of 0.9 mL/min at room temperature (25°C). The linear regression equations of Na+, K+, Mg2+, Ca2+ were = 4.4763c  + 0.0209, = 3.8903c  – 0.0087, = 6.3974c  – 0.0173, and = 7.601c  – 0.0339 and the limits of detection of Na+, K+, Mg2+, Ca2+ were 0.296, 4.98, 0.0970, and 1.22 μg/L, respectively. In this work, four cations in samples were successfully detected.  相似文献   

19.
This paper describes the novel preparation of three kinds of nanofibers [poly(styrene-co-methacrylic acid), poly(styrene-co-p-styrene sulfonate), polystyrene] investigated as solid-phase extraction (SPE) sorbents to extract six compounds (nitrobenzene, 2-naphthol, benzene, n-butyl p-hydroxybenzoate, naphthalene, p-dichlorobenzene) in environmental water by high-performance liquid chromatography. Parameters affecting extraction efficiency were investigated in detail to explore the extraction mechanism of the nanofibers. Under optimized conditions, six compounds followed an excellent linear relationship in the range 10–5,000 ng mL−1 with coefficients of determination (r 2) greater than 0.99. The repeatability (expressed as relative standard deviations) was from 3.0 to 7.0%, corresponding to 2.0 mL of water samples at 25 and 500 ng mL−1 spiked levels for the six compounds. The limits of detection varied from 0.01 to 0.15 ng mL−1 (signal-to-noise ratio of3). A comparison of the SPE using nanofibers as sorbents and the most commonly used octadecylsilica SPE cartridges was carried out in terms of absolute recovery, sensitivity, and reproducibility for the compounds investigated. Finally, the method was applied to four real water samples. The results highlighted the importance of functional groups, and the polarity of nanofibers in controlling sorption of target compounds, and clearly showed that the new method could be a viable and environmentally friendly technique for analyzing pollutants in environmental samples.  相似文献   

20.
《Arabian Journal of Chemistry》2020,13(12):8499-8512
The present study introduces a high efficiency metal alloy-based solid-phase microextraction (SPME) fiber coated with a green biowaste nanocomposite of chicken feet yellow membrane mixed with graphene oxide (CFYM/GO). An Al/Cr commercial heating element (aluchrom, AC) has been selected as the fiber substrate and designed as coiled form (CAC-SPME) to enhance its extraction and pre-concentration capacity. The fabricated fiber, CAC-SPME/CFYM/GO, has been employed for the extraction and pre-concentration of some commonly seen PAHs in different standard/real samples prior to their high performance liquid chromatography- ultraviolet (HPLC-UV) analyzing. The synthesized materials and the fibers surface were characterized by field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy analysis and Brunauer-Emmett-Teller surface area analysis. Under the optimized experimental conditions, low detection limits (LOD, 0.039–0.30 µg L–1), wide linear ranges (LR, 0.13–643 µg L–1) and good relative recoveries (RR, 76.20–105.60%) were achieved for all the target analytes. The materials applied to prepare this fiber were low-priced and accessible and also eliminated the need for expensive coating substances. In addition, using of the AC alloy substrate was increased the fiber physicochemical resistance and solved the breakage drawback of the conventional SPME fibers. Moreover, simple fabrication, high rigidity, long service life and high extraction capacity were some of the other advantages of the suggested fiber. Therefore, the proposed method can be utilized successfully for the routine analysis of PAHs in different matrixes.  相似文献   

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