Preparation and characterization of a novel Co(II) optode based on polymer inclusion membrane

A greener analytical procedure based on automated flow through system with an optical sensor is proposed for determination of Co(II). The flow through system consisted of polymer inclusion membrane (PIM) containing potassium thiocyanate (KSCN) that was placed between the measuring cell and fixed with optical sensor probe as an optical sensor for monitoring of Co(II) at 625 nm. In the presence of Co(II) ions, the colourless membrane changes to blue. The sensing membrane was prepared by incorporating SCN into a non plasticized PIM. The prepared PIM were found to be homogenous, transparent and mechanically stable. The optode shows reversible optical response in the range of 1.00 × 10⁻⁶ – 1.00 × 10⁻³ mol L⁻¹ with detection limit of 6.10 × 10⁻⁷ mol L⁻¹. The optode can be regenerated by using 0.1 mol L⁻¹ of ethylenediaminetetraacetic acid (EDTA). The main parameters of the computer controlled flow system incorporating the flow-through optode, a multi-port selection valve and peristaltic pump were optimized too. The calculated Relative Standard Deviation (R.S.D) of the repeatability and reproducibility of the method are 0.76% and 4.73%, respectively. This green system has been applied to the determination of Co(II) in wastewater samples with reduced reagents and samples consumption and minimum waste generation.