Preconcentration Of Silver Ion Research Articles

Selective ion-imprinted polymers for preconcentration and determination of silver in water and hair by electrothermal atomic absorption spectrometry

A new Ag(I)-ion imprinted polymer (IIP) was prepared by formation of 2-(4-hydroxypent-3-en-2-ylideneamine) phenol complex for selective extraction and preconcentration of silver ions. Polymerization was performed with ethylene glycol dimethacrylate as crosslinking monomer and methacrylic acid as functional monomer in the presence of 2,2-azobis(isobutyronitrile) as initiator via bulk polymerization method. The Ag(I)-imprinted polymeric particles were characterized by scanning electron microscopy and infrared spectroscopy. The template silver ion was removed from the polymeric matrix using 2.0 M HNO3. Optimum pH for maximum sorption was 6.0. Maximum sorbent capacity and enrichment factor for Ag(I) were 12.5 mg/g and 50, respectively. The relative standard deviation and detection limit of the method were evaluated as ±4% and 2.3 ng/L, respectively. The developed IIP has also been tested for preconcentration and recovery of Ag(I) ions from water and hair samples.

Synthesis of Nano-Pore Size Ag(I)-Imprinted Polymer for the Extraction and Preconcentration of Silver Ions Followed by Its Determination with Flame Atomic Absorption Spectrometry and Spectrophotometry Using Localized Surface Plasmon Resonance Peak of Silver Nanoparticles

Silver ion imprinted polymer (IIP) was synthesized in the presence of Ag(I)-N,N’-bis(salicylidene) ethylenediamine (salen) complex using 4-vinylpyridine as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as the crosslinker, and 2,2-azobis(isobutyronitrile) (AIBN) as the initiator. The Ag(I)-imprinted polymer (IIP) particles were characterized by SEM (scanning electron microscope), FTIR (Fourier transform infrared spectroscopy) and BET/BJH (BrunauerEmmett-Teller/Barrett-Joyner-Halenda) analysis. The imprinted Ag(I) ions were completely removed by leaching the IIP with thiourea (0.5 mol L -1 ). The polymer was employed as a selective sorbent for extraction and separation of the trace amounts of the Ag(I) ions. The preconcentrated ion was determined via the flame atomic absorption spectrometry (FAAS) or it was reduced to silver nanoparticles and quantified by spectrophotometry based on its localized surface plasmon resonance peak (LSPRP). The figures of merit of both methods were compared. Under the optimized conditions, a sample volume of 80 mL resulted in an enhancement factor of 312. The detection limit (3Sb/m) and the relative standard deviation (n = 10) at 10 µg L -1 level for FAAS were found to be 0.06 µg L -1 , 2.9%, whereas for the LSPRP method they were 0.5 µg L -1 and 10.3%, respectively. The methods were successfully applied to the determination of silver in radiology film, hair, nails, and water samples.

Electrochemical synthesis of Ag nanoparticles supported on glassy carbon electrode by means of p-isopropyl calix[6]arene matrix and its application for electrocatalytic reduction of H2O2

The silver nanoparticles were prepared on the glassy carbon (GC) electrode, modified with p-iso propyl calix[6]arene, by preconcentration of silver ions in open circuit potential and followed by electrochemical reduction of silver ions. The stepwise fabrication process of Ag nanoparticles was characterized by scanning electron microscopy and electrochemical impedance spectroscopy. The prepared Ag nanoparticles were deposited with an average size of 70nm and a homogeneous distribution on the surface of electrode. The observed results indicated that the presence of calixarene layer on the electrode surface can control the particle size and prevent the agglomeratione and electrochemical deposition is a promising technique for preparation of nanoparticles due to its easy-to-use procedure and low cost of implementation. Cyclic voltammetry experiments showed that Ag nanoparticles had a good catalytic ability for the reduction of hydrogen peroxide (H2O2). The effects of p-isopropyl calix[6]arene concentration, applied potential for reduction of Ag+, number of calixarene layers and pH value on the electrocatalytic ability of Ag nanoparticles were investigated. The present modified electrode exhibited a linear range from 5.0×10−5 to 6.5×10−3M and a detection limit 2.7×10−5M of H2O2 (S/N=3) using amperometric method.

Determination of trace silver in environmental samples by room temperature ionic liquid-based preconcentration and flame atomic absorption spectrometry

We report on a new method for preconcentration of silver ion at trace level in environmental samples, and its subsequent determination by flame atomic absorption spectrometry (FAAS). The room temperature ionic liquid (RTIL) 1-butyl-3-methylimidazolium hexafuorophosphate and the chelator 5-(4-dimethylaminobenzylidene)-rhodanine were used for extraction. Ag(I) was back-extracted from the organic phase into thiosulfate solution and then determined via FAAS. The effects of pH, concentration of chelating agent, extraction time and temperature, amounts of ionic liquid, ionic strength and potentially interfering ions were studied. Under optimized conditions, the enhancement factor is 30 was achieved. The detection limit (3 σ) is 0.28 ng mL−1, and the relative standard deviation is 4.1% for 7 replicate determinations at 5 ng mL−1 of Ag(I). The method was validated by analysis of certified reference materials and applied to the determination of Ag(I) in environmental samples with satisfactory results.

Separation and Preconcentration of Silver Ion using Multiwalled Carbon Nanotubes as Solid Phase Extraction Sorbent

A new method has been developed for the determination of silver ion based on separation and preconcentration with a microcolumn packed with multiwalled carbon nanotubes (MWNTs) prior to its determination by flame atomic absorption spectrometry (FAAS). The optimum experimental parameters for separation and preconcentration of silver, `such as sample pH, sample flow rate and volume, elution conditions, and interfering ions, have been investigated. Silver ion can be quantitatively retained by MWNTs in the pH range 7∼9, and then eluted completely with 1.0 M HNO3. The detection limit of this method for Ag was 0.60 ng mL−1, and the relative standard deviation (RSD) was 3.8% at the 10 ng mL−1 Ag level. The method has been successfully applied for the determination of trace silver in geological and water samples.

Di ( n-propyl) thiuram disulfide bonded on silica gel as a new sorbent for separation, preconcentration, and measurement of silver ion from aqueous samples

A new synthesized sorbent, di ( n-propyl) thiuram disulfide bonded on silica gel, was applied for separation and preconcentration of silver ion from aqueous samples. Factors influencing the sorption and desorption of silver ion were investigated. An aqueous solution containing sodium thiosulfate was used as eluent in order to selectively desorb the adsorbed silver ion from the surface of the sorbent. A preconcentration factor of 100 was achieved. The effect of coexisting ions in binary mixtures, containing silver ion and the foreign ion, on percent recovery of silver ion was investigated. Mercury(II) ion showed interfering effect. Separation selectivities for each metal ion of Zn 2+, Cu 2+, Co 2+, Ni 2+, Al 3+, Hg 2+, Pb 2+, Ca 2+, Cr 3+, Mg 2+, and Fe 3+ were measured. The relative standard deviation under optimum conditions was 1.43% ( n = 10). This system was applied for determination of silver ion in photographic waste and lakewater samples.

On-line separation and preconcentration of silver ion on amidino-thiourea immobilized glass beads packing in flow injection analysis with atomic absorption spectrometric detection.

Amidino-thiourea immobilized glass beads (AGB I) were prepared and used as the microcolumn packing for the flow injection (FI) on-line separation and preconcentration of Ag(I) coupled with atomic absorption spectrometry (AAS) determination. Base metal ions and anions with a concentration of 2.0 mg mL(-1) had no interference with the determination of Ag(I). The limit of detection (LOD) of Ag(I) for a preconcentration time of 60 s with a sampling flow rate of 5.0 mL min(-1) for 40.0 ng mL(-1) of Ag(I) were 0.50 ng mL(-1) with the peak-height absorbance mode and 1.26 ng mL(-1) with the peak-area absorbance mode, respectively. The relative standard deviations (RSD) of 7 replicate determinations were 0.9% and 0.7% for the peak-height absorbance (H) and the peak-area absorbance (A), respectively. The method was successfully applied to the determination of Ag(I) in ore samples.

Separation and preconcentration of silver ion using 2-mercaptobenzothiazole immobilized on surfactant-coated alumina

A new adsorbent for preconcentration and separation of silver ion from aqueous sample solutions has been reported. Sodium dodecyl sulfate (SDS), as a surfactant, makes admicelle on the surface of substrate γ-alumina, which allows the metal complexing agent, 2-mercaptobenzothiazole (MBT), to be immobilized in its hydrocarbon cores. This assemble, as a chelating adsorbent, has made the separation and preconcentration of silver ion possible. Factors influencing the adsorption of μg/ml levels of silver ion concentration from solutions by the adsorbent have been investigated. A preconcentration factor of 100 has been found. An aqueous solution containing thiourea has been used in order to selectively desorb the adsorbed silver ion from the surface of the adsorbent, which is a new stripping technique that is introduced in solid-phase extraction methods. No serious interferences have been observed due to the presence of another species in the sample. The separation selectivity of the adsorbent for other cations was studied. To improve this, EDTA was added to the source solution before applying to the column. The method is simple and inexpensive.