scholarly journals Determination of selectivity coefficients of ion selective electrodes by continuous variation method.

1988 ◽  
Vol 4 (2) ◽  
pp. 149-151 ◽  
Author(s):  
Kazuo HIIRO ◽  
Shin-ichi WAKIDA ◽  
Masataka YAMANE
Keyword(s):  
Continuous Variation ◽  
Variation Method ◽  
Ion Selective Electrodes ◽  
Selectivity Coefficients ◽  
Continuous Variation Method

scholarly journals SPECTROPHOTOMETRIC STUDY ON THE FORMATION AND ANALYTICAL APPLICATION OF THE RHODIUM (III) CHELATE WITH 2-THIOXO-4-THIAZOLIDINONE

2002 ◽  
Vol 10 (11) ◽  
pp. 89-96
Author(s):  
Ion Ganescu ◽  
Vasilica Muresan ◽  
Liana Simona Sbirna ◽  
Anca Ganescu ◽  
Sebastian Sbirna ◽  
...  
Keyword(s):  
Binary System ◽  
Spectrophotometric Determination ◽  
Spectrophotometric Study ◽  
Continuous Variation ◽  
Analytical Application ◽  
Variation Method ◽  
Instability Constant ◽  
Formation Conditions ◽  
Continuous Variation Method

The paper presents a spectrophotometric study of the binary system Rh(III)-2-thioxo-4-thiazolidinone. The formation conditions and the analytical application of the formed complex for spectrophotometric determination of Rh(III) were studied. The composition of the Rh(III) chelate with this particular ligand was determined by the continuous variation method, its instability constant being Kinst = 1,61·10-8 mol2L-2.

Cu(II) Ion-Selective Electrodes Based on Cu(II) Complex with Cyclized Salophen

2003 ◽  
Vol 58 (7) ◽  
pp. 658-662 ◽  
Author(s):  
Manal R. Al-Saraj ◽  
Salman M. Saadeh ◽  
Monzir S. Abdel-Latif
Keyword(s):  
Aqueous Solutions ◽  
Ion Selective Electrodes ◽  
Similar Response ◽  
Membrane Composition ◽  
Experimental Conditions ◽  
Selectivity Coefficients ◽  
Potentiometric Selectivity ◽  
Coated Disc ◽  
Coated Wire

Several versions of Cu(II) ion selective electrodes (ISE), based on cyclized N,N'-bis(salicylidene)-o-phenylenediamine (salophen) complexes with Cu(II), were fabricated for determination of Cu(II) in aqueous solutions. The response of the ISE was optimized by variation of membrane composition and evaluation of various experimental conditions. Near Nernstian slopes (~ 28-32 mV/decade) were obtained for some preparations. The linear range of the ISE ranged from 5 × 10-5 to 1 × 10-2M Cu(II). Coated-wire and coated disc ISE resulted practically in a similar response as screen printed electrodes (SPE). The potentiometric selectivity coefficients (Kij) for all electrodes were determined for Na+, NH4+, Ca2+, Mg2+, Ni2+, Pb2+, Zn2+, Cd2+, Co2+, Fe3+, Hg2+, CO32-, H2PO4-, HPO42-, SO42-, CH3COO-, Br-, I-, NO3-, and SCN-. The selectivity coefficients were in the range from 10-2 to 10-3 for all ions tested except Hg2+, I-, and to less extent Fe3+. Fabricated ISE using the Cu(II)-salophen complex are reliable and stable.

scholarly journals Determination of Stability Constants and Thermodynamic parameters of Cefotaxime –Fe(III) Complex at Different Temperatures

2020 ◽  
Vol 45 (4) ◽  
Author(s):  
O. V. Ikpeazu ◽  
I. E. Otuokere ◽  
K. K. Igwe
Keyword(s):  
Stability Constants ◽  
Chelating Agent ◽  
Continuous Variation ◽  
Molar Ratio ◽  
Variation Method ◽  
Ratio Method ◽  
Lactam Antibiotic ◽  
Different Temperatures ◽  
Mole Ratio Method ◽  
Continuous Variation Method

Cefotaxime, a β-lactam antibiotic, has a structure which enables it to act as a chelating agent. The formation of Fe(III) complex with cefotaxime has been studied colorimetrically at an absorption maximum of 480 nm at different temperatures. The data showed that Fe(III) and cefotaxime combine in the molar ratio of 1:1  at pH 7.4 with ionic strength maintained using 0.1M KNO3. The stability constants of the complex were calculated to be 1.56 - 1.90 x 104 by continuous variation method and 1.34 - 1.71 x 104 by mole ratio method at 25 and 40 oC respectively. ∆HƟ values for the complex were calculated to be -1.02 x 104 and -1.05 x 104 J by continuous variation method and mole ratio method respectively. ∆GƟ of the complex were calculated to be -2.44 – (-2.51) x 104 J by continuous variation method and -2.41- (- 2.48)  x 104 J by mole ratio method at 25 and 40 oC.  ∆SƟ of the complex were calculated to be 2.44 - 2.51 x 104 J/K by continuous variation method and -2.41 -2.48) x 104 J/K by mole ratio method at 25 and 40 oC respectively. Cefotaxime is a good chelating agent and can be an efficient antidote in the therapy of copper overload or poisoning.  

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