Centri-voltammetric study with amberlite XAD-7 resin as a carrier system (original) (raw)
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Separation Science and Technology, 2007
The use of a newly synthesized chelating resin with an o‐aminophenol–type functional groups and Amberlite XAD‐1180–type supporting material for separation/preconcentration of trace metal ions from various water samples was described. Amberlite XAD‐1180‐o‐aminophenol chelating resin (XAD‐o‐AP) was synthesized using Amberlite XAD‐1180 resin as solid support and o‐aminophenol as the chelating ligand. The determination of Cd(II), Co(II), Cu(II), Ni(II), and Pb(II) ions was made by flame atomic absorption spectrometry (FAAS). Studying with model solutions for the optimization of the method was based on the measurement of recovery values (between 92–106%) of the analyte elements. Some analytical parameters such as pH (6.0), volume of the sample (250 mL), effect of matrix ions, flow rates of the sample (2.5 mL min−1) and elution solutions (2.5 mL min−1), concentration, type and volume of the eluent (4 mol L−1 HNO3, 20 mL) were investigated. The detection limit (3s/b, n=20) and the relative standard deviation (n=7) of the method were found to be in the range 0.9–4.3 µg L−1 and 4.4–5.5%, respectively. The proposed method was successfully applied to the real samples such as wastewater, boiler feeding water and a certified reference material (Estuarine water, LGC 6016).
Amberlite XAD-4 resin (AXAD-4) has been functionalized by coupling it through an sNdNs group with 1-(2-pyridylazo)-2-naphthol (PAN). The resulting chelating resin, PAN-AXAD-4, has been characterized by using elemental and thermogravimetric analysis, infrared spectra, water regain value, and hydrogen ion capacity. The sorption capacity was found to be (285, 145, 135, 85, and 76) µmol · g -1 for Zn(II), Co(II), Ni(II), Cu(II), and Pb(II), respectively. The kinetics was studied at different temperatures, and the corresponding rate constants were also determined. All the metals could be eluted with 5 mL of HNO 3 resulting in a high preconcentration factor of 300 to 500. The detection limits were found to be (0.65, 0.80, 0.85, 0.95, and 1.40) µg · L -1 for Zn(II), Co(II), Ni(II), Cu(II), and Pb(II), respectively. The validity of the method was checked by analyzing standard reference materials and performing recovery studies. The analytical utility of the PAN-AXAD-4 for preconcentration and determination of metal ions was explored by analyzing river, canal, sewage, tap water, multivitamin formulation, and infant milk substitute by direct as well as the standard addition method.
Anal Chem, 1995
analyte ions and fixed positive/negative charges of a stationary phase, having the special advantage of using only water as the mobile phase. Initial results showing two elutions of the same analyte gave new insights into the mechanism of EIC. It suggests that the zwitterionic stationary phase, like a single charged stationary phase, has a Stern layer and a diffuse layer. The first elution is from the di €t'use layer, and the second is from the Stem layer, As simpler analysis is facilitated by a single elution, a new species of inorganic salt with a longer elution time was added to the original sample solution in order to release analyte ions from the Stern layer to the diffuse layer, The newly introduced salt is called a s a c s c e species, Without preconcentration, inorganic ions at subppb levels were successfully detected by this method.
The paper describes the results of stripping voltammetry usage to control concentration of lead ion which are formed during electrochemical detoxication of organic pollutants. Optimal conditions for the analysis of Pb 2+ were selected, i.e. 0.05 N KOH is an electrolyte, the deposition potential (-0.55) V, deposition time of 4 minutes, the amount of analyzed sample was 0.1 ml. The presence of organic matter does not affect the quantitative determination of lead ions. The developed method allows us to estimate the concentration of Pb 2+ in the amount of electrolyte at disposal of toxicants quickly and with a high degree of sensitivity.
Voltammetric Determination of Lead at Chemically Modified Electrodes Based on Crown Ethers
Analytical Sciences, 2001
The feasibility of fabricating lead-sensitive chemically modified electrodes (CMEs) for trace analysis in aqueous and 40%(v/v) ethanol-water media was investigated. Carbon paste electrodes modified with crown ethers were constructed by mixing the crown ethers into a graphite powder-paraffin oil matrix. The thus-formed electrodes were able to bind Pb(II) ions chemically, and gave better voltammetric responses than unmodified ones. The crown ethers studied and compared were 18-crown-6 and dibenzo-18-crown-6. With a 5% 18-crown-6 CME, Pb(II) could be quantified at subppm levels by differential pulse voltammetry with a detection limit of 0.02 ppm. It was possible to selectively pick up Pb(II) from a solution of several other ions at an open circuit through complexation. A simultaneous analysis of Cu(II) and Pb(II) was also attempted. By differential pulse anodic stripping voltammetry Pb(II) could be quantified over the range of 1 to 100 ppb. Interference from metal ions like Ni(II), Co(II), Mn(II), Zn(II), Cd(II), Ag(I), Fe(III), Ca(II) and Mg(II) was also studied. The method was successfully applied to artificial as well as commercial samples of alcoholic beverages.
Revista de Chimie, 2018
The development of a new voltammetric method for the determination of Pb2+ ions in water samples using glassy carbon electrodes modified with 2,6-bis((E)-2-(thiophen-2-yl)vinyl)-4-(4,6,8-trimethylazulen-1-yl)pyrylium perchlorate is here presented. The analytical parameters for differential pulse voltammetry (DPV) were established and the method was applied for Pb2+ ions determination in acetate buffer solution at pH 5.5. For the developed DPV method the linearity of calibration curve was set up between 20.71mg L-1 - 103.6 mg L-1 with a good correlation coefficient R2=0.9988, the intermediate precision was calculated for three lead concentrations:20, 60,100mg L-1.The obtained detection and quantification limits were 3.1 mg L-1, respectively 10.4 mg L-1. An uncertainty budget was developed and the value of expanded uncertainty was assessed. The optimized method was used to analyze Pb2+ ions from of water samples and good correlation with standard method was obtained.
Journal of Electroanalytical Chemistry, 2014
The aim of this manuscript is to develop a combined method for the detection and remediation of Pb 2+ species in aqueous environment. The electrocoagulation (EC) process of Pb 2+ has been studied, using an electrolytic flow cell equipped with Al sacrificial electrodes and by working under galvanostatic conditions (by applying currents of 0.25, 0.5 and 0.75 A). The concentration of Pb 2+ during EC was monitored by Adsorptive Stripping Voltammetry (AdSV) and data were also confirmed by Atomic Absorption Spectroscopy (AAS). The experimental results of EC showed that the performances of the process slightly depend on the applied current; a complete removal of the pollutant is obtained in all cases, however with different treatment times (90, 75 and 45 min for 0.25, 0.5 and 0.75 A, respectively). Furthermore, the AdSV, when compared with the AAS, has shown that the electroanalytical approach represents a fast and quite reliable alternative for monitoring heavy metal remediation applications.
Talanta, 2002
An automated on-line preconcentration method was developed for simultaneous determination of Pb(II), Cd(II) and Zn(II) by square-wave anodic stripping voltammetry (SWASV) using bismuth film screen-printed carbon electrode (Bi-SPCE). The preconcentration of metal ions was performed with a mini-column of a chelating resin, which was installed on a switching valve in the automated system consisted of a syringe pump, an 8-port selection valve and a switching valve. The laboratory-assembled automated on-line pretreatment system (Auto-Pret ASV system) was controlled by the Visual Basic program written by the authors. The metal ions collected on the resin were eluted with 1 M hydrochloric acid, subsequently transported into the flow cell for on-line deposition of analytes on Bi-SPCE at -1.4 V vs. Ag/AgCl; then the flow of the solution was stopped and the voltammogram was recorded from -1.2 to 0.2 V vs. Ag/AgCl by scanning a potential in the square-wave waveform. Experimental conditions, such as pH of sample, a sample flow rate, an eluent volume and its flow rate were optimized. Under the optimum conditions, the analytical characteristics were studied. In addition, the proposed method was applied to the analysis of water samples.
Talanta, 2008
The performance of a carbon paste electrode (CPE) modified with SBA-15 nanostructured silica organofunctionalised with 2-benzothiazolethiol in the simultaneous determination of Pb(II), Cu(II) and Hg(II) ions in natural water and sugar cane spirit (cachaça) is described. Pb(II), Cu(II) and Hg(II) were pre-concentrated on the surface of the modified electrode by complexing with 2-benzothiazolethiol and reduced at a negative potential (−0.80 V). Then the reduced products were oxidised by DPASV procedure. The fact that three stripping peaks appeared on the voltammograms at the potentials of −0.48 V (Pb 2+), −0.03 V (Cu 2+) and +0.36 V (Hg 2+) in relation to the SCE, demonstrates the possibility of simultaneous determination of Pb 2+ , Cu 2+ and Hg 2+. The best results were obtained under the following optimised conditions: 100 mV pulse amplitude, 3 min accumulation time, 25 mV s −1 scan rate in phosphate solution pH 3.0. Using such parameters, calibration graphs were linear in the concentration ranges of 3.00-70.0 × 10 −7 mol L −1 (Pb 2+), 8.00-100.0 × 10 −7 mol L −1 (Cu 2+) and 2.00-10.0 × 10 −6 mol L −1 (Hg 2+). Detection limits of 4.0 × 10 −8 mol L −1 (Pb 2+), 2.0 × 10 −7 mol L −1 (Cu 2+) and 4.0 × 10 −7 mol L −1 (Hg 2+) were obtained at the signal noise ratio (SNR) of 3. The results indicate that this electrode is sensitive and effective for simultaneous determination of Pb 2+ , Cu 2+ and Hg 2+ in the analysed samples.