INVESTIGADORES
DASSIE Sergio alberto
artículos
Título:
Comparative analysis of alkali and alkaline-earth cations assisted transfer by monensin across the water/1,2-dichloroethane interface
Autor/es:
S.A. DASSIE; A.M.BARUZZI
Revista:
JOURNAL OF ELECTROANALYTICAL CHEMISTRY
Editorial:
ELSEVIER
Referencias:
Lugar: Amsterdam; Año: 2000 vol. 492 p. 94 - 102
ISSN:
0022-0728
Resumen:
In the first part of this paper the electrochemical transfer of alkali cations (M) assisted by monensin (HX) across the
water 1,2-dichloroethane (DCE) interface at pHB5, combined with a chemical exchange reaction at 5BpHB9, is proposed as
the only mechanism responsible for the transfer of these cations. At pH\9 the current is voltammetrically negligible. An equation
for the dependence of Do
wf1:2 on pH and Na concentration is developed. In the second part of the paper the transfer of alkaline
earth cations assisted by the same ionophore is studied. The electrochemical reactions (Me(w)
2HX(o)?MeHX2
(o) ) and
(Me(w)
2X
(o)? MeX
(o)) are responsible for the peaks observed at pHB5.0 and at pH\9.0, respectively. As expected, in both
cases DEp0.030 V while at intermediate pH the electrochemical exchange reaction (Me2
(w) HX(o) ?MeX
(o)H
(w)) is
proposed. The net charge transfer of 1 at the interface accounts for DEp0.060 V for the peak observed DEp in agreement with
the hyper-Nernstian slope of 60 mV found for Ca2 and Ba2 ISE based on antibiotics with carboxylic groups at intermediate
pH values. The higher selectivity for Ba2 and the tendency in selectivity at alkaline pH found in the ISEs are also observed and
thus explained according to the mechanism proposed.