Development of Perchlorate-Selective Coated Graphite Electrode Based on Crystal Violet and its Appliction to the Determination of Ethylene Glycol, Glycerol, Glucose and Mannitol Via Periodate Oxidation
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Date
2009-07
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Addis Ababa Universty
Abstract
An attempt was made to develop perchlorate-selective coated graphite electrode based on
crystal violet using 1-chloronaphthalene as plasticizer. The electrode prepared by coating crystal
violet-perchlorate ion association in 1-chloronaphthalene both as the plasticizer and the solvent
with a PVC matrix on a graphite rod was found to give a Nernstian response to perchlorate in a
wide concentration range. Proper response of the electrode was observed in test solutions made
in 0.1 moleL-1 potassium nitrate solution. The linear range, slope, and detection limit from the
plot of E vs log [ClO4
-] were found to be 1.0 x 10-5-1.0 x 10-1 mol L-1, 58±1.5 mV/decade and
3.16 x 10-6 mole L-1 perchlorate respectively. The electrode was also used to detect periodate
with linear range, slope and detection limit of 1.0 x 10-4-1.0 x 10-2 mol L-1, 57±1.5 mV/decade
and 5.7 x 10-5 mole L-1 periodate respectively. The response time of the electrode was found to
be < 20 s for concentrations higher than 1.0 x 10-4 M and the electrode functioned properly for
four weeks. The effect of the amount of the electroactive ion pair was also studied and it was
found that electrode prepared from 20-30 mg of the crystal violet perchlorate was chosen with
the best response. The effects of diverse ions on the electrode response to perchlorate were
studied and the potentiometric selectivity coefficients were evaluated. The electrode was found
to be highly selective to perchlorate and periodate. The analytical application of the electrode
was extended to the direct determination of perchlorate and periodate and to the indirect
determination of ethylene glycol, glycerol, glucose and mannitol via periodate oxidation.
KEY WORDS: Ion selective electrode (ISE), coated graphite electrode (CGE), ethylene glycol,
glycerol, glucose and mannitol.
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Keywords
Ion selective electrode (ISE); coated graphite electrode (CGE); ethylene glycol; Glycerol; glucose and mannitol.