Synthesis of four derivatives of 3,6,10-tri(carboxymethyl)-3,6,10-triazadodecanedioic acid, the stabilities of their complexes with Ca(ii), Cu(ii), Zn(ii) and lanthanide(iii) and water-exchange investigations of Gd(iii) chelatesElectronic supplementary information (ESI) available: tables of pM values and relaxivities; potentiometric titration curves for TTDA-PY, TTDA-HP, TTDA-H1P and TTDA-H2P; species distribution curves, plots of temperature dependence of transverse electronic relaxation rates and plots of pH dependence of conditional stability constants for Gd complexes of all four ligands and TTDA; 1H NMR and COSY spectra of [La(TTDA-HP)]–. See http://www.rsc.org/suppdata/dt/b1/b107456n/

2001 ◽  
pp. 3357-3366 ◽  
Author(s):  
Tsan-Hwang Cheng ◽  
Yun-Ming Wang ◽  
Kuei-Tang Lin ◽  
Gin-Chung Liu
Keyword(s):  
Water Exchange ◽  
Ph Dependence ◽  
Supplementary Information ◽  
Electronic Relaxation ◽  
Conditional Stability ◽  
Relaxation Rates ◽  
Titration Curves ◽  
Conditional Stability Constants ◽  
Derivatives Of ◽  
Cosy Spectra

Comparative study of organic Cd and Zn complexation in lake waters - seasonality, depth and pH dependence

2007 ◽  
Vol 4 (6) ◽  
pp. 410 ◽  
Author(s):  
Sylvia Sander ◽  
Léticia Ginon ◽  
Barry Anderson ◽  
Keith A. Hunter
Keyword(s):  
New Zealand ◽  
Stability Constants ◽  
Ph Dependence ◽  
Cadmium Concentration ◽  
Stripping Voltammetry ◽  
Alpine Lakes ◽  
Zinc Binding ◽  
Pyrrolidine Dithiocarbamate ◽  
Conditional Stability ◽  
Conditional Stability Constants

Environmental context. The bioavailability of trace metals such as zinc and cadmium strongly depends on what chemical form they are in, and not simply on the total metal concentration. Zinc is an essential micronutrient, whereas cadmium is extremely toxic, but when they occur in the same environment there is potential for the two metals to compete for the same biological binding sites. In this study we have studied the trends in Cd and Zn complexation in three alpine lakes in New Zealand. We conclude that, although the total concentration of cadmium is much lower than that of zinc and copper, it bares the highest risk of toxicity for organisms. Abstract. The variation with depth, pH dependence, seasonal variability and selectivity of strong, natural organic cadmium and zinc-binding ligands from three New Zealand alpine lakes (Hayes, Manapouri and Hauroko) have been investigated. Competitive ligand equilibration–cathodic stripping voltammetry (CLE-CSV) with APDC (ammonium pyrrolidine dithiocarbamate) was used to measure the ligand complexation by Zn2+ and anodic stripping voltammetry (ASV) for complexation of Cd2+. In all lakes, the total dissolved cadmium concentration [CdT] averaged 0.040 nM (standard deviation σ = 0.114), while the average concentration of Cd-binding ligands [LCd] was 5.17 ± 1.79 nM (1σ), with conditional stability constants relative to free Cd2+, log K′Cd2+L′, that ranged from 7.92 at depth to 10.58 at the surface. Calculated concentrations of the free aquo ion [Cd2+] averaged 0.0147 ± 0.0616 nM (1σ), and showed a higher percentage of Cd complexed by strong ligands in the summer and in surface waters. The selectivity of cadmium-binding organic ligands was low, and ligand-bound Cd2+ was easily displaced by Zn2+ and Cu2+. Total dissolved zinc concentrations [ZnT] were highly variable, and ranged from 1.04 to 10.94 nM. The corresponding ligand concentrations of strong zinc-binding ligands [LZn] were between 2.14 and 15.52 nM, with conditional stability constants log K′Zn2+L′ as low as 8.78 in deep water collected in summer from Lake Hauroko, up to a maximum of 12.41 at a depth of 5 m in Lake Hayes. The calculated concentrations of the free aquo complex [Zn2+] ranged widely between 0.001 and 1.620 nM.

Spectrophotometric study of the interaction of Chromazurol S and Eriochromazurol B with surface active substances - tensides

1981 ◽  
Vol 46 (5) ◽  
pp. 1090-1106 ◽  
Author(s):  
Irena Burešová ◽  
Vlastimil Kubáň ◽  
Lumír Sommer
Keyword(s):  
Critical Micellar Concentration ◽  
Spectrophotometric Study ◽  
Conditional Stability ◽  
Acid Base ◽  
Binary Complexes ◽  
Chromazurol S ◽  
Acid Base Equilibrium ◽  
Poorly Soluble ◽  
Conditional Stability Constants ◽  
Triton X

The acid-base and optical properties of Chromazurol S and Eriochromazurol B in the presence of 1 . 10-6 - 2 . 10-2M solutions of cetylpyridinium bromide, cetyltrimethylammonium bromide and 1-ethoxycarbonylpentadecyltrimethylammonium bromide (Septonex) and 0.001-1.0% w/v solutions of octylphenolpolyethylene glycol ether (Triton X-100), polyoxyethylenemonolauryl ether (Brij 35) and lauryl sulphate sodium salt were determined by graphical and numerical interpretation of absorbance curves. The poorly soluble ion associates, which can be extracted into chloroform and which have the defined composition [LH4-nn-.n T+] or [LH3-nn-.n T+] are formed at submicellar concentration of the tenside. In regions close to the critical micellar concentration of the tenside, soluble binary complexes of the acid-base forms of the reagent are formed with tenside micelles. The conditional stability constants of the reagent acid-base equilibrium depend on the type and concentration of the tenside, on the reagent concentration, on the concentration and type of inorganic acid anions and on the ionic strength of the solution. The mechanism of interaction of the reagent with the tenside and the probable structure of the binary species are discussed.

Effect of pH, humus concentration and molecular weight on conditional stability constants of cadmium

1988 ◽  
Vol 22 (11) ◽  
pp. 1381-1388 ◽  
Author(s):  
Jan John ◽  
Brit Salbu ◽  
Egil T. Gjessing ◽  
Helge E. Bjørnstad
Keyword(s):  
Molecular Weight ◽  
Stability Constants ◽  
Conditional Stability ◽  
Effect Of Ph ◽  
Conditional Stability Constants

Temperature- and pH-dependence of proton relaxation rates in rat liver tissue

1995 ◽  
Vol 13 (3) ◽  
pp. 429-440 ◽  
Author(s):  
E. Moser ◽  
E. Winklmayr ◽  
P. Holzmüller ◽  
M. Krssak
Keyword(s):  
Rat Liver ◽  
Liver Tissue ◽  
Ph Dependence ◽  
Proton Relaxation ◽  
Relaxation Rates
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