Extraction of electrolytes from aqueous solutions and their spectrophotometric determination by use of acid-base chromoionophores in lipophylic solvents.
The formation of non-absorbing complexes in an organic phase has been exploited for the spectrophotometric determination of ionic analytes in aqueous solutions. The method is based on liquid-liquid extraction of aqueous solution with lipophylic organic phases containing an acid-base chromoionophore, a neutral lypophilic ligand (neutral carrier) selective to the analyte and a cationic (or anionic) exchanger. The method avoids all difficulties of the preparation of the very thin membranes used in optodes, so that it can advantageously be used for the study of the role physical-chemical parameters of the system in order to optimize them and to prepare, if necessary, an optimized optode. Two lipophylic derivatives of Nile Blue and 4',5-dibromofluorescein have been synthesized, in order to ensure their permanence within organic phase. Two different neutral carriers previously characterized by us as ionophores for liquid-membrane Ion Selective Electrodes have been employed. Three different ionic exchangers have been tested. Furthermore, a model allowing the interpolation of experimental data and the determination of the thermodynamic constant of the ionic-exchange equilibrium has been developed and applied.
Barberi
Paola
P
Dipartimento di Chimica Generale ed Inorganica, Chimica Analitica, Chimica Fisica, Università di Parma, Parco Area delle Scienze 17/A, I-43100 Parma, Italy.
Giannetto
Marco
M
Mori
Giovanni
G
D004573:Electrolytes / Q000032:analysis*; D007474:Ion Exchange; D007476:Ionophores; D012997:Solvents; D013053:Spectrophotometry / Q000379:methods*; D013816:Thermodynamics; D014867:Water / Q000737:chemistry
D004573:Electrolytes; D007476:Ionophores; D012997:Solvents; D014867:Water