A polystyrene-based membrane of 3,4:11,12-dibenzo-2,5,10,13-tetraoxo-1,6,9,
14-tetraazacyclohexadecane was prepared and investigated as a Ni2+-selectiv
e electrode. The best performance was observed with the membrane having pol
ystyrene to ligand composition of 1:6, which worked well over a wide concen
tration range, 3.16 x 10(-6)-1.00 x 10(-1) mol L-1 with a near Nernstian sl
ope of 30.7 mV per decade of activity between pH 2.5 to 7.0. The electrode
exhibits a fast response time of 10s and was used over a period of 2 months
with good reproducibility (S = +/- 0.2 mV). The selectivity coefficient va
lues for monovalent, bivalent and trivalent cations indicate excellent sele
ctivity for Ni2+ ions and it also works satisfactorily in a partially nonaq
ueous medium of methanol and ethanol. The practical utility of the membrane
sensor was observed in solutions contaminated with detergents, cetyltrimet
hylammonium bromide and sodium dodecyl sulfate and the sensor was used succ
essfully to determine nickel in electroplating waste.