A Novel Optical Chemical Sensor to Determine Samarium Ions in Aqueous Solutions

A novel, fast and sensitive optical chemical sensor has been prepared for the determination of samarium(III) in aqueous solutions using 4-(5-bromo-2-pyridylazo)-N,N-diethyl-3-hydroxyanilin (Br-PADAP) as an ionophore in the plasticized PVC membrane. The complex formation between Sm(III) and Br-PADAP caused a new peak in the absorption spectra at 525 nm. The prepared optode had a linear dynamic range for 2.6 × 10⁻⁶ to 2.6 × 10⁻⁴ mol L⁻¹ samarium(III) concentration. The lower and upper detection limits of the optode were found to be 1.9 × 10⁻⁶ and 3.0 × 10⁻⁴ mol L⁻¹ Sm(III), respectively. The response time of the optode for 2.4 × 10⁻⁵ and 2.4 × 10⁻⁴ mol L⁻¹ Sm(III) were found to be 300, and 200 s, respectively. The relative standard deviations for measuring the absorbance of the optode when immersed in the 2.8 × 10⁻⁵ mol L⁻¹ Sm(III) was 1.4%. Investigation of the selectivity of the optode revealed its good selectivity to Sm(III) when compared with other cations. The proposed optode was applied for the determination of Sm(III) in water samples and certified reference materials with satisfactory recovery.