Effect of temperature on the selectivity coefficient of a polymeric membrane sensor for Gd³⁺ detection

In nuclear industry, gadolinium as gadolinium nitrate is used as neutron poison in the moderator system owing to its very high thermal neutron absorption cross section. Due to the same reason presence of gadolinium in the nuclear fuel is also not desirable. Therefore determination of gadolinium at trace level is very important. Potentiometric sensor has many advantages over other analytical techniques. However, determination of Gd³⁺ potentiometrically suffers from the possible interference from other lanthanide elements. Selectivity coefficient is a parameter by which the effect of interference is measured. Temperature can play a vital role to tune the selectivity coefficient of the sensor. In the present investigation the effect of temperature on the selectivity coefficient of Gd³⁺ over La³⁺ (model lanthanide) was determined using a Gd³⁺ based sensor prepared in house with a 9-membered aza crown ether scaffhold tethered with three diglycolamide (L_I) as ionophore in a polyvinyl chloride matrix. The selectivity coefficient data suggest that the La³⁺ is less interfering in the Gd³⁺ determination at lower temperature