Comparative solid phase extraction study on the U(VI) preconcentration by using immobilized thermotolerant <Emphasis Type="Italic">Bacillus vallismortis</Emphasis> and <Emphasis Type="Italic">Bacillus mojavensis</Emphasis>

Bacillus vallismortis and Bacillus mojavensis were loaded onto Amberlite XAD-4 resin and used for solid phase extraction (SPE) of uranium(VI). A quick and simple UV–Vis spectrophotometric method was used to determine U(VI) ion. The best experimental conditions were determined as being a pH of 5.0; a sample flow rate of 2.0 mL min^?1; 200.0 mg of biosorbent; 800 mg of Amberlite XAD-4, and 5.0 mL of 1 mol L^?1 HCl as desorption solution for both immobilized bacteria. The preconcentration factors were achieved as 80 for both solid phase extractor. The developed methods were validated by applying to reference water and tea samples.     

Geobacillus thermoleovorans immobilized on Amberlite XAD-4 resin as a biosorbent for solid phase extraction of uranium (VI) prior to its spectrophotometric determination

Geobacillus thermoleovorans subsp stromboliensis, was immobilized on an Amberlite XAD-4 ion exchanger and used as a solid phase extractant for the preconcentration of U(VI) ions prior to their determination by UV-VIS spectrophotometry. Parameters affecting the preconcentration (such as the pH value of the sample solution, the concentration of U(VI), the volume and type of eluent, the flow rate and the effect of potentially interfering ions) were studied. The optimum pH for the sorption of U(VI) was found to be pH 5.0. 5.0?mL of 1 M hydrochloric acid were used to eluate the U(VI) from the column. The loading capacity is 11?mg?g^?1. The limits of detection and quantification are 2.7 and 9.0?μg?L^?1, respectively, and relative standard deviations are <10?%. The method was applied to the determination of U(VI) in a certified reference sample (NCS ZC-73014; tea leaves) and in natural water samples.

Salen impregnated silica gel as a new sorbent for on-line preconcentration of cadmium(II)

A new sorbent – salen impregnated silica gel – was prepared and characterised for application as a minicolumn packing for flow-injection on-line preconcentration of cadmium(II). The system was coupled with flame atomic absorption spectrometer (FI-FAAS). The optimal pH for Cd(II) sorption was in the range of 7.4–8.8 and nitric acid (1%, v/v) was efficient as eluent. Sorption was most effective within the sample flow rate up to 7?mL?min^?1. Sorption capacity of the sorbent found in a batch procedure was 26.3?µmol?g^?1 (2.95?mg?g^?1). Enrichment factor (EF) and limit of detection (LOD) obtained for 120-second loading time were 113 and 0.26?µg?L^?1, respectively. The sorbent stability in the working conditions was proved for at least 100 preconcentration cycles. The evaluated method was applied to Cd(II) determination in various water samples.     

Preconcentration and Determination of Copper(II) by Novel Solid-Phase Extraction and High-Resolution Continuum Source Flame Atomic Absorption Spectrometry

Amberlite XAD-4 modified with N-para-anisidine-3,5-di-tert-butylsalicylaldimine was investigated as a new chealting sorbent for the selective separation and preconcentration of Cu(II). The metal ion was retained by chemical sorption on the modified resin, eluted by hydrochloric acid, and determined by high-resolution continuum source flame atomic absorption spectrometry. The prepared resin was characterized for the solid-phase extraction of Cd²⁺, Co²⁺, Cr³⁺, Cu²⁺, Fe³⁺, Mn²⁺, Ni²⁺, Pb²⁺, and Zn²⁺ in a column. The influence of the pH, the mass of solid phase, eluent, flow rate, and sample volume was optimized. Using the optimum conditions, only Cu(II) showed quantitative sorption at the 95% confidence level, and the recoveries of the other metal ions were below 80%. A preconcentration factor 125 was obtained for Cu(II) with a limit of detection of 0.56?µg?L^?1. The method was used for the determination of Cu(II) in tap water, river water, tomato leaves, and fish. The relative standard deviation and the relative error were lower than 7%.     

Determination of Trace Metal Ions in SeaWater by Atomic Absorption Spectrometry After Separation/Preconcentration with Calmagite on Amberlite Xad-1180

A preconcentration/separation method for the atomic absorption spectrometric determinations of Cu(II), Ni(II) and Pb(II) ions in seawater have been established by using a chromatographic column filled Amberlite XAD-1180. The recoveries of Cu(II), Ni(II) and Pb(II) ions were quantitative (> 95%) at pH 8-9. The influences of the various analytical parameters including the amount of calmagite, amount of Amberlite XAD-1180, eluent type, etc. were investigated. The influence of the seawater matrix was also examined. Simultaneous enrichment and determination of copper, nickel and lead ions in seawater are possible with satisfactory results (recoveries > 95%, RSD <9%).     

Preconcentration of cadmium and nickel using the bioadsorbent Geobacillus thermoleovorans subsp. stromboliensis immobilized on Amberlite XAD-4

Cadmium and nickel ions have been preconcentrated on Geobacillus thermoleovorans subsp. stromboliensis, immobilized on Amberlite XAD-4, and were determined by flame atomic absorption spectrometry (FAAS). Parameters such as pH, amount of adsorbent, eluent type and volume, flow rate of solution and the matrix interference effect on retention have been studied, and extraction conditions were optimized. Elution of Cd(II) and Ni(II) from minicolumns was carried out with 1.0 M hydrochloric acid or nitric acid with recoveries from 97 to 100%. The sorption capacity is 0.0373 and 0.0557 mmol g^?1 for Cd(II) and Ni(II), respectively. The detection limits were 0.24 μg L^?1 for cadmium and 0.3 μg L^?1 for nickel. The relative standard deviations of the procedure were below 10%. The procedure was validated by analyzing certified reference materials and applied to the determination of Cd(II) and Ni(II) in natural water and food samples.     

Solid phase extraction and flame atomic absorption spectrometric determination of trace amounts of cadmium and lead in water and biological samples using modified TiO2 nanoparticles

A solid phase extraction procedure for the separation and preconcentration of trace amounts of Cd(II) and Pb(II) using the alizarin red S modified TiO₂ nanoparticles prior to their determination by flame atomic absorption spectrometry has been proposed. The influences of some analytical parameters such as pH, flow rates of sample and eluent, type and concentration of the eluent, and interfering ions on the recovery of Cd(II) and Pb(II) by the sorbent were investigated. The analytes were quantitatively sorbed from the aqueous solution at pH 5.5 onto a microcolumn packed with the sorbent and recovered with 2.0?mL of 1.5?mol?L^?1 hydrochloric acid. Under the optimum experimental conditions, the detection limits for Cd(II) and Pb(II) were 0.11 and 0.30?ng?mL^?1 and the relative standard deviations for ten replicate measurements of 5.0 and 50.0?ng?mL^?1 of Cd(II) and Pb(II) were 2.1 and 1.9%, respectively. A sample volume of 200?mL resulted in a preconcentration factor of 100. The method was successfully applied to the determination of Cd(II) and Pb(II) in water and biological samples, and accuracy was examined by the recovery experiments, independent analysis using electrothermal atomic absorption spectrometry, and analysis of a water standard reference material (SRM 1643e).     

Water hyacinth modified carbon paste electrode for simultaneous electrochemical stripping analysis of Cd (II) and Pb (II)

In this study, we demonstrated a highly sensitive electrochemical sensor for the simultaneous detection of Pb (II) and Cd (II) in aqueous solution using carbon paste electrode modified with Eichhornia crassipes powder by square wave anodic stripping voltammetry. The effect of modifier composition, pH, preconcentration time, reduction potential and time, and type of supporting electrolyte on the determination of metal ions were investigated. Pre-concentration on the modified surface was performed at open circuit. The modified electrode exhibited well-defined and separate stripping peaks for Pb (II) and Cd (II). Under optimum experimental conditions, a linear range for both metal ions was from 10 to 5000 μg L^?1 with the detection limits of 4.9 μg L^?1, 2.1 μg L^?1 for Cd(II) and Pb (II), respectively. The modified electrode was found to be sensitive and selective when applied to determine trace amounts of Cd (II) and Pb (II) in natural water samples.     

Differential Pulse Polarographic Determination of Cd(II) and Pb(II) in Milk Samples after Solid‐Phase Extraction Using Amberlite XAD‐2 Resin Modified with 2,2′‐DPED3P

In the present paper novel column solid phase extraction procedure was developed for the determination of Cd(II) and Pb(II) in cows', goats', ewes', buffalos' and humans' milk samples using newly synthesized reagent 2,2′‐DPED₃P (2,2′‐{[1,2‐diphenylethane‐1,2‐diylidene]dinitrilo}diphenol) for preconcentration and separation prior to differential pulse polarography using amberlite XAD‐2 in the ranges of pH 4.0–5.0. The sorbed elements were subsequently eluted with 10 mL of 2 M HCl elutes were analysed by differential pulse polarography (DPP). The interference of foreign ions has also been studied. Effects of various instrumental parameters are investigated and received conditions are optimized. The total metal concentration of the milk samples in the study area were in the following ranges 0.030–0.090 μg L^?1 of Cd(II), 0.009–0.026 μg L^?1 of Pb(II) respectively. The limits of detections were found to be 0.020 and 0.024 μg L^?1 for Cd(II) and Pb(II) respectively by applying a preconcentration factor ～40. The proposed enrichment method was applied successfully for the determination of metal ions in cows', goats', ewes', buffalos' and humans' milk samples.     

Solid-phase extraction of Hg(II) on creatine modified activated carbon and determination by ICP-OES in water samples

A new sorbent was successfully prepared by immobilizing creatine on activated carbon and then used for separation/preconcentration of trace Hg(II) prior to detection by inductively coupled plasma optical emission spectrometry (ICP-OES). Experimental conditions including pH, sample flow rate and volume, eluting variables and tolerance limit of interfering ions were evaluated and established. At pH 1.0 and flow rate of 2.5?mL?min^?1, Hg(II) was adsorbed quantitatively on the column, then quantitatively eluted by 2.0?mL 0.1?mol?L^?1 nitric acid solution; other transition metal ions did not interfere with the determination of Hg(II). An enrichment factor of 100 was obtained for Hg(II). The maximum adsorption capacity was 49.5?mg?g^?1. Under the optimal conditions, the value of the detection limit (3σ) was 0.06?ng?mL^?1, and the relative standard deviation (RSD) calculated was lower than 3.0% (n?=?8). The methodology was validated by analyzing certified reference materials and successfully applied to the determination of trace Hg(II) in natural water samples with satisfactory results.     

Preconcentration and separation of metal ions by means of amberlite XAD-2 loaded with pyrocatechol violet

On the non-ionic sorbent Amberlite XAD-2 the sulphonated derivative of an aromatic complexing agent-Pyrocatechol Violet-was immobilized, and this chelate-forming resin was used for the preconcentration of Pb(II) and In(III) and for the separation of some metal ions. The PV-XAD-2 resin was adopted for the preconcentration of Pb(II) in tap-water. Very high preconcentration factors were obtained.     

Novel Imprinted Polymer for the Preconcentration of Cadmium with Determination by Inductively Coupled Plasma Mass Spectrometry

A novel Cd(II)-imprinted polymer was prepared with chemical immobilization using N-methacryloyl-L-Histidine as a vinylated chelating agent for online solid-phase extraction of Cd(II) for determination by inductively coupled plasma mass spectrometry. The Cd(II)–monomer complex was synthesized and copolymerized through bulk polymerization method in the presence of ethyleneglycoldimethacrylate cross-linker. The resulting polymer was leached with 1.0?mol?L^?1 HNO₃ to generate the cavities in the polymer for Cd(II) ions. The experimental conditions, including load pH, solution flow rate, and eluent concentration for effective sorption of Cd(II), were optimized using a minicolumn of the imprinted polymer. A volume of 5.0?mL sample 5?µg?L^?1 Cd(II) solution at pH 6.5 was loaded on the column at 2.0?mL?min^?1 using a sequential injection system followed by elution with 1.0?mL of 0.75?mol?L^?1 HNO₃. The relative selectivity coefficients of the imprinted polymer for Cd(II) were 38.5, 3.5, 3.0, 2.5, and 6.0 in the presence of Cu(II), Ni(II), Zn(II), Co(II), and Pb(II), respectively. Computational calculations revealed that the selectivity of the imprinted polymer was mediated by the stability of Cd(II)–N-methacryloyl-L-Histidine complex which was more stable than commonly used monomers including 4-vinyl pyridine, methacrylic acid, and vinylimidazole. The detection limit and relative standard deviation were 0.004?µg?L^?1 and 3.2%, respectively. The method was validated by the analysis of seawater certified reference material (CASS-4) and successfully used for the determination of Cd(II) in coastal seawater and estuarine water.     

Selective preconcentration of Lanthanum(III) by Coriolus versicolor immobilised on Amberlite XAD-4 and its determination by ICP-OES

Coriolus versicolor, a wood fungus, was immobilised on Amberlite XAD-4 and used as solid-phase biosorbent for preconcentrations of rare earth elements. La(III), Th(IV), U(IV) and Ce(III) were subjected to solid-phase extraction procedure. We observed that La(III) was selectively preconcentrated, while other ions remained in solution at pH 6.0. 5.0 mL of 1.0 mol L^?1 HCl was used to elaute La(III) from column. 250 mg of C. versicolor loaded on 1000 mg of XAD-4 was optimised as solid-phase matrix. Concentrations of ions in solutions were determined by inductively coupled plasma– optical emission spectrometry (ICP-OES). The calibration plot after preconcentration was linear in the range from 1.0 to 50.0 ng mL^?1 for La(III). Limit of detection was found as 0.27 ng mL^?1 for La(III) by SPE method. Relative standard deviation was found lower than 6.7% for 1.0 ng mL^?1 of La(III) solution (n = 10). The sensitivity of ICP-OES was improved by a factor of 46.8. The applicability of the method was validated through the analysis of certified reference samples of tea (NCS ZC-73014) and spinach (NCS ZC-73013).     

Flow injection dual-syringe sorbent extraction platform for metal determination in environmental matrices utilizing a new strong cation exchange sorbent micro-cartridge and flame atomic absorption spectrometry

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.     

Synthesis and Application of New Resin Functionalized by Brilliant Green for Spectrophotometric Determination of Mercury in Environmental Samples

Abstract

A new chelating resin was prepared by coupling Amberlite XAD-4 with brilliant green through an azo spacer, and it has been used for preconcentration and separation of mercury(II) in environmental samples prior to its determination by spectrophotometry. The sorption capacity of functionalized resin is 4.12 mg g^?1. Spectrophotometric determination of Hg(II), free from the interference of almost all cations and anions found in the environmental water samples, is a notable advantage of the method. The determination of Hg(II) in wastewater and seawater was carried out by the present method and cold vapor atomic absorption spectrometry (CVAAS).     

Use of clinoptilolite loaded with 1-(2-pyridylazo)-2-naphthol as a sorbent for preconcentration of Pb(II), Ni(II), Cd(II) and Cu(II) prior to their determination by flame atomic absorption spectroscopy

A solid phase extraction system for separation and preconcentration of trace amounts of Pb(II), Ni(II), Cd(II) and Cu(II) is proposed. The procedure is based on the adsorption of Pb²⁺, Ni²⁺, Cd²⁺ and Cu²⁺ ions on a column of 1-(2-pyridylazo)-2-naphthol (PAN) immobilised on surfactant-coated clinoptilolite prior to their determinations by Flame Atomic Absorption Spectroscopy (FAAS). The effective parameters including pH, sample volume, sample flow rate and eluent flow rate were also studied. The analytes collected on the column were eluted with 5 mL of 1 mol L^?1 nitric acid. A concentration factor of 180 can be achieved by passing 900 mL of sample through the column. The detection limits (3 s) for Cd, Cu, Pb and Ni were found to be 0.28, 0.12, 0.44 and 0.46 µg L^?1, respectively. The relative SDs at 10 µg L^?1 (n = 10) for analytes were in the range of 1.2–1.4%. The method was applied to the determination of Pb, Ni, Cd and Cu in water samples.     

Separation and pre-concentration of palladium(II) from environmental and industrial samples by formation of a derivative of 1,2,4-triazole complex on Amberlite XAD–2010 resin

A simple separation/pre-concentration method was developed for extraction of Pd(II) in various environmental samples, based on its adsorption of 4–phenyl–5–{[(4–phenyl–5–pyridin–4–yl–4H–1,2,4–triazole–3–yl)thio]methyl}–4H–1,2,4–triazole–3–thyol (PPTTMET) complex on Amberlite XAD–2010 resin in a mini column. The ligand has high affinity for Pd(II) among many other metals that are taken into consideration. The flame atomic absorption spectrometry is employed to determine the concentration of Pd(II). The optimum working conditions which were determined are as follows: 0.05?mol?L^?1 HNO₃ as working medium, 1.0?mol?L^?1 HCI in acetone as elution solvent, 0.75?mg of PPTTMET amount and 750?mL of sample volume. The system was independent from the flow rates between 3.1 and 23.1?mL?min^?1. The Pd(II) adsorption capacity of Amberlite XAD–2010 resin was found to be 12.8?mg?g^?1 and the enrichment factor was calculated as 375. The method was successfully applied for the determination of Pd(II) in motorway dust samples, anodic sludge, gold ore, industrial electronic waste materials and various water samples.     

A novel method for the simultaneous determination of Pb (II), Cd (II) and Zn (II) in environmental water samples

A novel UV-VIS spectrophotometric method was developed in this study by using solid phase extraction procedure for the simultaneous preconcentration, separation and determination of trace levels of Pb (II), Cd (II) and Zn (II) ions in various water samples by using Amberlite N,N-bis(salicylidene)cyclohexanediamine (SCHD) resin. This study presents the results of experimental procedures carried out like the adsorption of analytes to the resin, influences of some analytical parameters that effect the recovery such as pH, sample volume, sample flow rate, eluent type and concentration, eluent volume, eluent flow rate and the effects of alkaline metals, earth alkaline metals and some other transition metals. The analytes in the samples with the adjusted pH range of 4–7 were adsorbed on XAD-4-SCHD resin and eluted by using 1.0 mol L^?1 nitric acid. The amounts of ions were determined by using UV-VIS spectrometer. The limits of detection were 0.03, 0.07 and 0.05 µg mL^?1 for Pb (II), Cd (II) and Zn (II), respectively. The accuracy of the method was assured by the analysis of the certified standard water sample NW-TMDA-70.2 and the observed recoveries were above 93%. Different environmental water samples that contain trace amounts of Pb (II), Cd (II) and Zn (II) were analysed by using the method developed in this study. Same samples were also analysed by ICP-MS for comparison and almost the similar results were observed. The method developed in this study was successfully applied to the various environmental water samples to determine the trace levels of Pb (II), Cd (II) and Zn (II) ions.     

Automatic flow system for evaluation of polystyrene-divinylbenzene sorbents applied to preconcentration of phenolic pollutants

In this work, an evaluation of commercially available polystyrene-divinylbenzene sorbents for solid-phase extraction (SPE) of eleven phenolic compounds is intended. Considering the particle size and cross-linking degree, Amberlite XAD-4 (commercial or grounded), Macronet MN-200 and Lichrolut EN were tested. The SPE protocol was performed by an automatic system, providing repeatable experimental conditions for assessment of sorbent capacity, breakthrough volume and enrichment factor (EF). A positive correlation between EF and log?K _ow was found for Amberlite XAD-4 while a negative correlation was observed between EF and molecular weight of analyte for Macronet MN-200 and for Lichrolut EN. This indicates a prevalence of hydrophobic interactions or molecular exclusion depending upon the polymer cross-linking degree. Despite the similar repeatability (RSD?<?4.7%, n?>?6) and recovery values attained (97.6–102.7%, using 50?mL of sample) for all sorbents, Lichrolut EN is the best choice for analytical application as higher EF and lower LOD values (between 18 and 207?ng) were attained for this sorbent.     

Amberlite XAD-7 impregnated with Xylenol Orange: a chelating collector for preconcentration of Cd(II), Co(II), Cu(II), Ni(II), Zn(II) and Fe(III) ions prior to their determination by flame AAS

A new chelating resin, Xylenol Orange coated Amberlite XAD-7, was prepared and used for preconcentration of Cd(II), Co(II), Cu(II), Fe(III), Ni(II) and Zn(II) prior to their determination by flame atomic absorption spectrophotometry. The optimum pH values for quantitative sorption of Cd(II), Co(II), Cu(II), Fe(III), Ni(II) and Zn(II) are 4.5–5.0, 4.5, 4.0–5.0, 4.0, 5.0 and 5.0–7.0, respectively, and their desorptions by 2 mol L^–1 HCl are instantaneous. The sorption capacity of the resin has been found to be 2.0, 2.6, 1.6, 1.6, 2.6 and 1.8 mg g^–1 of resin for Cd, Co, Cu, Fe, Ni and Zn, respectively. The tolerance limits of electrolytes, NaCl, NaF, NaI, NaNO₃, Na₂SO₄ and of cations, Mg²⁺ and Ca²⁺ in the sorption of the six metal ions are reported. The preconcentration factor was between 50 and 200. The t_1/2 values for sorption are found to be 5.3, 2.9, 3.2, 3.3, 2.5 and 2.6 min for the six metals, respectively. The recoveries are between 96.0 and 100.0% for the different metals at preconcentration limits between 10 to 40 ng mL^–1. The preconcentration method has been applied to determine the six metal ions in river water samples after destroying the organic matter (if present in very large amount) with concentrated nitric acid (RSD ≤ 8%, except for Cd for which it is upto 12.6%) and cobalt content of vitamin tablets with RSD of ～ 3.0%.