Presence Of Masking Agents Research Articles

Spectrophotometric determination of iron and copper ions in industrial wastewater, cooling water and scale of power station

Sensitive and selective spectrophotometric procedures were proposed for the determination of Fe(III) and Cu(II) using simple chromogenic reagents. The procedure of iron determination was based on the formation of ternary complex between Fe(III) and 4,7-diphenyl-1,10-bathophenanthroline (DPBP)–eosin in acid medium. On the other hand, the procedure of copper (II) determination was based on the formation of ternary complex between Cu(II) and 4,7-diphenyl-1,10-bathophenanthroline (DPBP)–Eriochrome Black-T (EBT) in alkaline medium. The ternary complexes were extracted in the presence of cetyltrimethyl ammonium bromide with chloroform. The molar absorptivities of the Fe(III)–DPBP–eosin and Cu(II)–DPBP–EBT ternary complexes were 2.23 · 105 and 9.35 · 104 L mol−1 cm−1 at 542 and 565 nm, respectively. Beer’s law is valid over the concentration ranges from 0.280 to 7.814 and from 0.320 to 8.260 μg mL−1 for Fe(III) and Cu(II), respectively. Sandell sensitivity (0.0025 and 0.0679 ng cm−2), relative standard deviation (0.257–1.94 and 0.305–1.85), limits of detection (0.076 and 0.045 μg mL−1) and quantification (0.253 and 0.150 μg mL−1) for Fe(III) and Cu(II) ions, respectively, are calculated. The procedures are applied for the determination of Fe(III) and Cu(II) in different polluted water sources, drinking water, river water as well as cooling water and boiler scales. The results obtained are compared with those obtained using atomic absorption spectroscopy. The effects of different tolerances are studied in the presence of masking agents.

Complexation reactions between lanthanum, gadolinium, and ytterbium and reagents of Arsenazo III group on the surface of fibrous materials loaded with a Chelex 100 ion exchanger

The complex formation reaction between La(III), Gd(III), and Yb(III) with Arsenazo III, Arsenazo M, and Chlorophosphonazo III after adsorption on polyacrylonitrile fiber loaded with an ion exchanger with iminodiacetate groups Chelex 100 has been studied. The influence of medium acidity, duration of the contact of the solution with the adsorbent, the presence of masking agents, and the concentrations of ions on the analytical signals of complexes in the solid phase has been investigated. It has been shown that there is a possibility to perform sorption-spectroscopic determination of the total concentration of the indicated elements using Chlorophosphonazo and the sum of lanthanum and gadolinium with Arsenazo M after adsorption from malonic acid solutions.

Estimation of the role of side reactions in the simulation of complexometric titration

A mathematical model was selected to describe the titration of metal ions with an arbitrary reagent in the presence of masking agents. The model takes into account the stepwise character of the complexation reaction and side reactions of protonation, hydrolysis and masking. The computed titration curves were in good agreement with the data of potentiometric titration. The corresponding program was used to optimize the titration conditions, to select promising titrants (other than complexones), and to predict systematic errors due to the shift of the titration jump in the presence of masking agents. Because of the last-named effect, the results of analysis may be underestimated several times

Determination of Trace Arsenic and Selenium in Copper and Nickel Powders by Hydride-Generation Atomic Absorption Spectrometry after Chelex Separation

Trace arsenic and selenium in copper or nickel powder were determined, after separation with Chelex 100 resin, by hydride-generation atomic absorption spectrometry in the presence of masking agents. When recoveries of arsenic or selenium were checked in the presence of copper or nickel ion in solution, they were quantitative. On the contrary, the recoveries of arsenic or selenium added to copper powder were not quantitative without masking agents, which may be due to partial elution of copper from the resin. Accuracies tested with an NBS Standard Reference Material were within the certified values.

Extraction of Niobium (V) by Tri-n-butyl Phosphate from Strongly Acid Solutions in the Presence of Masking Agents

Extraction of Niobium (V) by Tri-n-butyl Phosphate from Strongly Acid Solutions in the Presence of Masking Agents

“Ligand Buffer”: A concept useful in the theoretical consideration of equilibria involving chelating agents : Precipitation and solvent extraction in Ligand Buffers

The concept “ligand buffer” is proposed for a system containing a ligand and an excess of metal. The general properties of the ligand buffer are discussed in connexion with the results of pA calculations under various conditions. The “ligand buffer” concept and pA calculations are useful in the consideration of various equilibria involved in solvent extraction, precipitation, etc., in the presence of masking agents.