An optical redox chemical sensor for determination of iodide

A novel optical sensor based on a redox reaction for the determination of iodide has been developed. The optode membrane is constructed by immobilization of methyltrioctylammonium chloride on triacetylcellulose polymer. The exchange of chloride as counter ion with iodate in the membrane changes the color to yellow, when it is placed in acidic solution of iodide. The sensor can readily be regenerated by 0.1 mol L−1 NaOH in less than 15 s. The optode has a linear range of 3.94 × 10−6 to 5.51 × 10−5 mol L−1 of iodide ions with a limit of detection 7.44 × 10−7 mol L−1. The relative standard deviation for eight replicate measurements of 3.94 × 10−6 and 1.57 × 10−5 mol L−1 of iodide was 2.83 and 1.38%, respectively. The sensor was successfully applied to the determination of iodide in tablet, powdered milk and urine samples.