Abstrakt

Development of perchlorate-selective coated graphite electrode basedon crystal violet and its appliction to the determination of ethylene glycol, glycerol, glucose and mannitol via periodate oxidation.

Atnafu Guadie, Sushil Kumar Sen, Ghirma Moges, Negussie Megersa

The developed perchlorate-selective coated graphite electrode based on crystal violet (crystalviolet-perchlorate ion association in 1- chloronaphthalene both as the plasticizer and solvent with a PVCmatrix on a graphite rod) gave Nernstan 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 with linear range, slope, and detection limit of 1.0 x 10-5- 1.0 x 10-1mol/L perchlorate, 58±1 mV/decade, and 3.16 x 10-6 moleL-1 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 10-2molL-1, 57±1.5 mV/decade and 5.7 x 10-5moleL-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 periodat. 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.