Development a simple optical sensor for lead (II) based on immobilized 2-(5-bromo-2-pyridylazo)-5-(diethylamino) phenol

An optical sensor (optode) is described for a sensitive and selective spectrophotometric determination of Pb(II) ions in aqueous solution. A sensor is prepared by immobilization of 2-(5-Bromo-2-pyridylazo)-5-(diethylamino)phenol (Bromo-PADAP) on triacetylcellulose membrane[1]. The response of sensor is based on the complex formation between Pb(ІІ) and immobilized Bromo-PADAP at pH=7.5. Increasing in the absorbance of the sensing film at 575 nm was spectrophotometrically measured. Under the optimum conditions and 10, 15, 20 and 25 min response times, calibration curve was linear in the range of 0.5 – 25.0 mg L-1 of Pb(II) and the 3σ limit of detection was found 0.21, 0.12, 0.08 and 0.09 mg L-1, respectively. The optode developed here is found to be stable, cost, effective, easy to prepare, and efficient for direct determination of Pb(II) in a aqueous samples using spectrophotometry. The sensor can be regenerated by placing the film into a 0.010 M of hydrochloric acid solution for nine time sections that time of each section was 5 sec. This optical sensor was successfully used for measuring Pb(II)ions in different water samples[2].