Becauseofeaseof fabrication and cost, ion optical sensors are used in determination of various ions in aqueous and organic solutions. In this work,an?ion optical sensor for the determination of Pb(II) and Cd(II) is reported. 2-amino-1-cyclopentene-1-dithiocarboxylic acid (ACDA) immobilized on cellulose acetate film. Cellulose acetate film had previously been subjected to a base hydrolysis and then ACDA was immobilized on it. This film is shown a maximum absorbance peak at 388 nm. The absorption spectra of the optode membranes in Pb(II) and Cd(II) solutions showed a new peak at 423 and 430 nm, respectively, and this property was used as an analytical criteria. The effect of different parameters such as hydrolysis time, concentration of ACDA, immobilization pH, complexation pH, immobilization time and contact time were investigated. Under the optimal conditions, this sensor has wide linear response range of 1.0 ´ 10 -6 – 5.0 ´ 10 -4 M of Pb(II) ions with a detection limit of 6.9 × 10 -7 M (0.23 ppm) and 3.0 ´ 10 -6 –1.0 ´ 10 -4 M of Cd(II) ions with a detection limit of 2.6 × 10 -6 M.(0.52 ppm). The response time of the optode thin film was 10 min to reach 98% of the final signal (t 98 ). The relative standard deviation for eight replicate measurements of 4.0 ´ 10 -5 M and 1.5 ´ 10 -4 of Pb(II) were 3.0% and 3.4%, respectively, and for 8.0´10 -6 M and 5.0´ 10 -5 M Cd(II) were 2.7% and 2.3%, respectively. The influence of potential interfering ions on the determination of Pb(II) and Cd(II) were studied and the main interferences were removed by extraction method. The sensor was applied for determination of Pb(II) and Cd(II) in real samples including water samples and alloys.
