Investigation of a new “N2S2O2” chelating agent with high Po(iv) affinity

2017 ◽  
Vol 53 (48) ◽  
pp. 6492-6495 ◽  
Author(s):  
Ali Younes ◽  
Gilles Montavon ◽  
Sébastien G. Gouin ◽  
Emy André-Joyaux ◽  
Roxane Peumery ◽  
...  
Keyword(s):  
Stability Constant ◽  
Chelating Agent ◽  
Water Soluble ◽  
Complexing Agent ◽  
Conditional Stability ◽  
Conditional Stability Constant

A water-soluble complexing agent for 210-polonium decorporation was designed and synthesised with a high conditional stability constant.

scholarly journals Spectrophotometric investigation of famotidine-Pd(II) complex and its analytical application in drug analysis

2004 ◽  
Vol 69 (6) ◽  
pp. 485-492 ◽  
Author(s):  
Zagorka Koricanac ◽  
Tatijana Jovanovic ◽  
Jelena Petkovic ◽  
Dragica Minic-Popovic
Keyword(s):  
Ionic Strength ◽  
Stability Constant ◽  
Drug Analysis ◽  
Dosage Forms ◽  
Conditional Stability ◽  
Buffer Solution ◽  
Conditional Stability Constant ◽  
Spectrophotometric Methods ◽  
Optimum Ph ◽  
Ph Range

By using different spectrophotometric methods, it was found that famotidine and palladium(II) ions form a complex, Pd(II): famotidine = 1:1, which has an absorptionmaximum at 345 nm. The formation of the complex between famotidine and palladium(II) chloride in Britton?Robinson buffer solution in the pH range 2.23?8.50 was studied. The conditional stability constant of the complex at the optimum pH 2.62 and ionic strength 0.5M was found to be log K?= 3.742 ??0.025. The Beer?s law was verified over the famotidine concentration range from 5x10-5?6x10-4 M. The proposed method was found to be suitable for accurate and sensitive analysis of famotidine both as the substance (RSD = 1.02?1.80 %) and its dosage forms (RSD = 1.75?1.83 %).

scholarly journals The solubility of Ca(OH)2 in extremely concentrated NaOH solutions at 25°C

2012 ◽  
Vol 10 (2) ◽  
pp. 332-337 ◽  
Author(s):  
Attila Pallagi ◽  
Ágost Tasi ◽  
Attila Gácsi ◽  
Miklós Csáti ◽  
István Pálinkó ◽  
...  
Keyword(s):  
Ionic Strength ◽  
Stability Constant ◽  
Solubility Product ◽  
Hydroxo Complex ◽  
Solubility Data ◽  
Alkaline Solutions ◽  
Conditional Stability ◽  
Experimental Protocol ◽  
Conditional Stability Constant

AbstractThe solubility of Ca(OH)2 in aqueous NaOH solutions up to 12.50 M at 25°C has been determined. The solubility data obtained for NaOH concentrations lower than 3 M was compared with those published in the literature. The solubility of Ca(OH)2 steadily decreases with the increasing NaOH concentration. The solubility data obtained at a constant ionic strength (I = 1 M Na(Cl,OH)) enabled the determination of the conditional solubility product of Ca(OH)2(s) (lgLCa(OH)2 = − 4.10 ± 0.02). Formation of the hydroxo complex CaOH+(aq) was invoked to describe the variation of [Ca2+]T with [OH−]T. Its conditional stability constant was found to be lgKCaOH+ = 0.97 ± 0.02. The experimental protocol employed was proven to be suitable for accurate solubility determinations in rapidly equilibrating systems comprising of highly concentrated, alkaline solutions and containing analytes in the ppm range.

Complexation of cadmium(II) with water- and soil-derived fulvic acids: effect of pH and fulvic acid concentration

1979 ◽  
Vol 57 (11) ◽  
pp. 1263-1268 ◽  
Author(s):  
Robert A. Saar ◽  
James H. Weber
Keyword(s):  
Stability Constant ◽  
Fulvic Acid ◽  
Stability Constants ◽  
Acid Concentration ◽  
Conformational Changes ◽  
Fulvic Acids ◽  
Conditional Stability ◽  
Conditional Stability Constant ◽  
Weak Binding ◽  
Conditional Stability Constants

We studied the conditional stability constants of cadmium(II) bound to fulvic acid derived from water and soil, and found that (1) stability constants increased with increasing pH, and (2) stability constants decreased as we increased the fulvic acid concentration toward 70 mg/L. The second effect does not occur for the copper(II)–fulvate system. Conformational changes that occur when a fulvic acid solution becomes more concentrated apparently weaken sites that are otherwise more accessible to weak-binding cadmium. From pH 4 to 8, the overall conditional stability constant increases from 1.4 to 12 × 103 for water-derived fulvic acid and from 1.7 to 43 × 103 for soil-derived fulvic acid. Increases in fulvic acid concentration from 20 mg/L to 70 mg/L halve the conditional stability constant at a given pH.

scholarly journals Spectrophotometric determination of dothiepin hydrochloride in pharmaceuticals through ion-pair complexation reaction

2012 ◽  
Vol 18 (2) ◽  
pp. 339-347 ◽  
Author(s):  
Sameer Abdulrahman ◽  
Kanakapura Basavaiah
Keyword(s):  
Ion Pair ◽  
Pure Form ◽  
Bromocresol Green ◽  
Bromophenol Blue ◽  
Complexation Reaction ◽  
Conditional Stability ◽  
Conditional Stability Constant ◽  
Accuracy And Precision ◽  
Significant Difference

Two simple, sensitive and extraction-free spectrophotometric methods are described for the determination of dothiepin hydrochloride (DOTH) both in pure form and in pharmaceutical tablets. The methods are based on ion-pair complex formation between dothiepin base (DOT) and two acidic dyes, namely, bromophenol blue (BPB) or bromocresol green (BCG) with absorption maximum at 425 nm for BPB method or 430 nm for BCG method. Beer?s law is obeyed over the concentration ranges of 1.0-15.0 and 1.0-17.5 ?g mL-1 DOT for BPB and BCG methods, respectively. The molar absorptivity values and Sandell?s sensitivity values are reported for both methods. The limits of detection (LOD) and quantification (LOQ) were calculated to be 0.18 and 0.53 ?g mL-1 for BPB method, and 0.17 and 0.50 ?g mL-1 for BCG method, respectively. The stoichiometry of the complex in either case was found to be 1: 1 and the conditional stability constant (KF) of the complexes has also been calculated. The proposed methods were applied successfully to the determination of DOTH in pure form and in its tablet form with good accuracy and precision. Statistical comparison of the results was performed using Student's t-test and variance ratio F-test at 95% confidence level and there was no significant difference between the official and proposed methods with regard to accuracy and precision. Further, the validity of the proposed methods was confirmed by recovery studies via standard addition technique.

Effect of UVB Irradiation on Cu2+-Binding Organic Ligands and Cu2+ Speciation in Alpine Lake Waters of New Zealand

2005 ◽  
Vol 2 (1) ◽  
pp. 56 ◽  
Author(s):  
Sylvia Sander ◽  
Jonathan P. Kim ◽  
Barry Anderson ◽  
Keith A. Hunter
Keyword(s):  
New Zealand ◽  
Surface Waters ◽  
Natural Waters ◽  
Austral Summer ◽  
Organic Ligands ◽  
Conditional Stability ◽  
Uvb Radiation ◽  
Dissolved Metals ◽  
Conditional Stability Constant ◽  
Uvb Irradiation

Environmental Context. The bioavailability of dissolved metals in natural waters is directly affected by metal-sequestering agents. These agents include soil-derived matter and compounds released by microorganisms, since copper can support or inhibit aquatic microorganisms depending on concentration. During summer the levels of copper increase in surface waters, an effect intuitively attributable to increased ultraviolet light degrading the sequestering agents more effectively, leading to a concurrent release of the metal. This paper shows that the amount of degradation attributable to light is too low to explain the metal release and that a biological influence may instead be responsible. Abstract. The influence of UVB irradiation on the Cu2+ binding by natural organic ligands in six alpine lakes on the South Island, New Zealand, has been investigated using competitive ligand equilibration with salicylaldoxime and detection by cathodic stripping voltammetry (CLE-CSV). During austral summer 2002–2003 the total dissolved Cu ([Cu]T), the concentration of strong Cu2+-binding ligands ([L]T), and their conditional stability constant K´´ were determined in surface samples of all six lakes. All lakes exhibited appreciable concentrations of a strong Cu2+ binding ligand with similar K´´ values and concentrations always exceeding [CuT], thus dominating Cu2+ speciation. Four lakes (Hayes, Manapouri, Wanaka, Te Anau) showed no appreciable trend in [LT] throughout the summer, whereas in Lakes Wakatipu and Hawea [LT] increased steadily throughout this period. Laboratory UVB irradiation of lake water samples using a 400 W mercury lamp with a Pyrex glass filter (λ > 280 nm) showed that Cu2+-binding ligands are destroyed by UVB radiation, causing [L]T to decrease with a rate of –0.588 nmol L–1 h–1 (r2 0.88). From this we calculate that the in situ ligand destruction rate by UVB in summer for surface waters of these lakes is too small to significantly affect [LT], and conclude that variations in ligand concentrations must result from seasonally variable biological factors.

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