A novel dithiomacrocycle (4-phenyl-11-decanoyl-1,7-dithia-11-azacyclotetradecane-4-sulfide) has been synthesized and used as a new ionophore in order to develop a plasticized poly(vinyl chloride) membrane for copper ion detection. The performance of these novel planar copper(II)-selective potentiometric microelectrodes was investigated using potentiometric measurements. The developed microelectrodes exhibits a good linear response of 29.5 +/- 1 mV per decade within the concentration range of 1.0 x 10(-6) to 1.0 x 10(-2) M (r = 0.9995) of Cu2+. The detection limit was determined as 5.62 x 10(-7) M and the selectivity coefficients for possible interfering cations were evaluated. The microelectrodes are suitable for use with aqueous solutions of pH 3.5-6.0 and were found to be insensitive to the nature of the anions used in the sample. (c) 2006 Elsevier Ltd. All rights reserved.