Application of a Hydrazone Derivative in the Construction of a Polymeric Membrane Sensor for Nickel Ions

Based on the results of the complexation reaction between 1-acenaphthoquinone 1-thiosemicarbazone (L) and some metal ions in methanol, it was found that the ligand forms a stable 1:1 complex with Ni2+ ions among the range of ions tested. Accordingly, this hydrazone derivative was chosen and evaluated as an ionophore for use in the construction of polymeric membrane sensors with selectivity towards Ni ions. The resulting membrane electrode, under optimal conditions, had a Nernstian slope of 29.5±0.2 mV/decade over a wide concentration window of 1.0×10-6-1.0×10-1 M, and its limit of detection was as low as 5.0×10-7 M. The electrode had very good selectivity coefficients for other commonly occurring cations in its response range. The proposed potentiometric sensors possess response times of 10 sec, good reversibility, and are applicable for over 12 weeks after their first use. The response of the membrane sensor was pH-independent in the pH range of 5.0–8.0, and it was used in the analysis of nickel ions concertation in real water samples with satisfactory results. The electrode was also used in the potentiometric titration of nickel ions using a standard ethylenediaminetetraacetic acid (EDTA) solution at pH=6.0.