Preconcentration Of Ag Research Articles

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.

Cobalt determination with FI-FAAS after on-line sorbent preconcentration using 1-nitroso-2-naphthol

The suitability of 1-nitroso-2-naphthol (NN) as a complexing agent for on-line preconcentration of cobalt using C 18 microcolumn with FI-FAAS system has been tested. Various parameters affecting the complex formation and its elution were optimized. Reagent solution (2.5×10 −3 mol l −1) and aqueous sample solution acidified with 0.1% (v/v) nitric acid were on-line mixed in a reaction coil set at 65±1 °C and flowed through the microcolumn for 30 s. The pH of the mixed solution was adjusted to 3∼4 by adding HNO 3 (1 mol l −1) or NaOH (1 mol l −1) in the reagent solution. The adsorbed complexes in the microcolumn were eluted with ethanol (acidified to 1% nitric acid) in 10 s into the nebulizer of FAAS. A good precision (1.6% for 100 μg l −1 Co(II), n=10), high enrichment factor 17.2, with detection limit (3σ) 3.2 μg l −1, and sample throughput (90 h −1) were obtained. The method was applied on the certified reference materials (CRMs) i.e. NBS-362 and NBS-364 (special low alloy steel), for the determination of cobalt and the results were in good agreement with the certified values.

Electrochemical detection of silver ions and the study of metal–polymer interactions on a polybenzidine film electrode

Abstract Silver ions (Ag(I)) were preconcentrated efficiently at open circuit from aqueous silver nitrate solution into polybenzidine (poly-Bz) film electrodes. The poly-Bz films were electrodeposited by means of cyclic voltammetry from benzidine (Bz) in acidic aqueous solutions. It was found that preconcentration of Ag(I) ions into the film is highly dependent on the pH, being more favored at neutral pH, that is, when the nitrogen in imine–amine groups in the polymer chain are not protonated. Under these conditions the Ag(I) ions do not compete with the H + ions for the same site within the film. A simple diffusion model is assumed to explain the incorporation of Ag(I) ion into the poly-Bz electrodes. The distribution of the Ag(I) ion between the solution and film was established and a probable analytical application given.

Iron determination after on-line sorbent preconcentration by fi-fass using 1, 10-phenanthroline as a complexing agent

1, 10-Phenanthroline (phen) was tested as a complexing agent for on-line preconcentration of iron on RP-C18 material in a microcolumn with flow injection coupled with flame atomic absorption spectrometer (FI-FAAS). The on-line formed Fe(II)-phen complexes were adsorbed on the C18 sorbent material. Various parameters affecting the on-line Fe(II)-phen complex formation and its subsequent adsorption in the microcolumn as well as its elution into the nebulizer of AAS were optimized. A 2.5×10−3 mol/L phen in 2% through the microcolumn for 30 s. The adsorbed Fe(II)-phen complexes in the microcolumn were eluted with ethanol in 10 s into the nebulizer of AAS. Ascorbic acid (5×10−4 mol/L) was added to the sample solution for the reduction of Fe(III) to Fe(II). A good precision (RSD=1.1%,n=10), high enrichment factor (19) and sample throughput (90 h−1) with detection limit (3σ) of 3 μg/L were obtained. The method was applied on standard reference materials (i. e. mussel and tomato leaves,) for iron determination and yielded results agreeing well with certified values.

Copper determination after FI on-line sorbent preconcentration using 1-nitroso-2-naphthol as a complexing reagent

The suitability of 1-nitroso-2-naphthol as a complexing agent for on-line preconcentration of copper using RP-C18 material in a microcolumn with flow injection coupled with flame atomic absorption spectrometry (FI-FAAS) has been tested. Various parameters affecting complex formation, such as pH, sample flow rate, etc. and its elution into the nebulizer of FAAS were optimized. ¶A 5 × 10–3 mol/L reagent was on-line mixed with aqueous sample solution acidified with 0.1% (v/v) nitric acid ¶(pH 3–4) and flowed through the microcolumn for 30 s. The adsorbed complexes in the microcolumn were eluted with ethanol in 10 s into the nebulizer of FAAS. A good precision (1.7% for 50 μg/L copper, n = 12), high enrichment factor (19) with detection limit (3σ) 2.0 μg/L, and sample throughput (90 h–1) were obtained. The method was applied to certified reference materials seawater, mussel (biological), NBS-362 and NBS-364 (special low alloy steel), for the determination of copper, and the results were in good agreement with the certified values.

1,10-Phenanthroline as a complexing agent for on-line sorbent extraction/preconcentration for flow injection–flame atomic absorption spectrometry

1,10-Phenanthroline (phen) has been tested as a complexing agent for on-line preconcentration of copper, cadmium and cobalt, on RP-C 18 material in a microcolumn with a flow injection–flame atomic absorption spectrometric system. The on-line formed metal-phen complexes can be adsorbed on the C 18 sorbent material. Various parameters affecting complex formation and the subsequent complex adsorption in the microcolumn as well as its elution into the nebulizer of the spectrometer were optimized. A 2.5×10 −3 mol l −1 phen solution in 2% ethanol was mixed on-line with aqueous sample solution acidified with 0.1% (v/v) nitric acid to pH 5–6 and flowed through the microcolumn for 30 s. The adsorbed metal-phen complexes were eluted with ethanol in 10 s into the nebulizer. A good relative standard deviation (3.0%, 1.4%, 2.2% at 50, 50 and 100 μg l −1, n=14), high enrichment factors, 32, 32 and 22, with 3 σ detection limits of 0.3, 0.5 and 6.0 μg l −1 for Cu(II), Cd(II) and Co(II), respectively, and a sample throughput of 90/h were obtained. The method was applied to standard reference materials, i.e. seawater, mussel (biological) and GSS-1 (geological), for the determination of copper and cadmium; the results were in good agreement with the certified values.