Lanthanum (III) Ion Determination by a New Design Optical Sensor

A new selective and sensitive Lanthanum (La) ions optical sensor based on immobilization of -(2-aminoethyl)-salicylaldimine (AESI) on a triacetylcellulose membrane was prepared. The prepared optode exhibited a linear range of 30–150 part per billion (ppb) of the La (III) ion concentration with a detection limit of 14.38 ppb. The response time of the newly designed optode was derived within 30–60 s, depending on the La (III) ion concentration, however is independent to the pH of the solution in the range of 3–5. The proposed optode indicated a low detection limit, fast response time, and also remarkable selectivity regarding to the number of transition metals ions (i.e. Ce³⁺, Cu²⁺, Cd²⁺, Cr³⁺, Zn²⁺, Hg²⁺, and Fe²⁺). The optode was successfully regenerated with a thiourea solution, and its response which might be reversible and reproducible showed the relative standard deviation of less than 1.48%. This optode was applied for determining the La (III) ions in water samples.