ABSTRACT
A new selective reagent, S,S'-bis(2-aminophenyl)oxalate (H2L), for the extractive spectrophotometric determination of copper has been prepared. The ligand, H2L, forms a 1:1 complex with copper(II) in methanol. The molar absorptivity of Cu(II)-S,S'-bis(2-aminophenyl)oxalate complex in methanol is 5365 M(-1) cm(-1) at 504 nm. The method has been applied for the determination of copper in pharmaceutical formulations, environmental and foodstuff samples.
Subject(s)
Copper/analysis , Oxalates/analysis , Copper/isolation & purification , Environmental Pollutants/analysis , Food Analysis , Hydrogen-Ion Concentration , Indicators and Reagents , Ligands , Plants/chemistry , Reproducibility of Results , Solvents , Spectrophotometry, UltravioletABSTRACT
The solutions of nine alpha, omega-bis(3-alkyl(aryl)-4,5-dihydro-1H-1,2,4-triazol-5-on-4-yl) alkanes were titrated with tetrabutylammoniumhydroxide (TBAH) in methanol, using potentiometric methods. The half neutralization potentials values were found for all cases. Potentiometric titration curves of compounds in methanol with 0.03 M TBAH are similar to those of weak acids obtained in aqueous media with strong bases. Methanol is found to be a suitable medium for the weakly acidic compounds titrated since they are poorly dissolved in other organic solvents. A comparison among the compounds having the same alkyl chains between the two ring systems has shown that basicity increases and acidity decreases as the size of alkyl chains increases. However, the compound with a substituted phenyl group was found to be the most acidic one among the examined compounds indicating that phenyl group donates ring electrons less effectively to the system. This can be attributed to the stability of the benzene ring.
