POLYPYRIDINE DERIVATIVES AS IONOPHORES IN MERCURY ION SELECTIVE ELECTRODES
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Date
2010-02
Authors
BAKHTIARZADEH, FARIBA
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Abstract
This study reports on the fabrication, characterization and utilization of the
heterogeneous poly (Hg - 4-vinyl pyridine) membrane electrode. The electrode, with
tris (2-ethyl hexyl) phosphate as plasticiser, has a Nemstian response with slope of
30.71 ± 1 m V/decade in the concentration range of 10-7 to 10-2 M Hg2+, and in
solution of pH 3 to 4. It has response and life time of less than 25 s and 90 days,
respectively. The limit of detection is 5 x 10-8 M Hg2+. Interferences from other
cations are not serious, except of silver (1) at mercury (II) concentration less than 10-4
M. Analyses of water samples show that the proposed technique agrees well with the
standard method with correlation coefficient, R, 0.9998. The electrode is also
suitable as an indicator electrode in the potentiometric titration of Hg (II) with
iodide.
This study also investigate on the possibility of a composite graphite (CO)
electrode modified with poly (2, 6-diarninopyridine) (PDAP) used as a solid state-ion
selective electrode without plasticizer for the determination of mercury. The
monomer 2, 6-diaminopyridine (DAP) is polymerized onto CO from the 30 mM
DAP in sulfuric acid with ZnS04 supporting electrolyte. The resulting polymer
surface has been characterized by SEM, UV-Vis and FT-IR. The electrode displays
Nernstian response with slope of 28.3 ± I mV/decade in concentration range of
I x 10-6 to 1 x 10-1 M and in solution of pH 3 to 5. The limit of detection for the
electrode is 3 x 1 0-8 M. The electrode has a fast response time of 32 s. It is also used to
detennine mercury concentrations in natural waters. The electrode is also suitable as
an indicator electrode in the potentiometric titration of Hg (II) with iodide.
Description
Keywords
POLYPYRIDINE , IONOPHORES