Chemical sensor for lanthanum(III) determination using aza-crown as ionophore in poly(vinyl chloride) matrix Original Research Article

Lanthanum(III)-selective sensors have been fabricated from poly(vinyl chloride) (PVC) matrix membranes containing neutral carrier, monoaza-12-crown-4 as ionophore. Best performance was exhibited by the membrane having a composition crown:PVC:NaTPB:DBBP in the ratio 7:48:8:37 (w/w). This membrane works well over a wide concentration range of 3.16×10−5 to 1.00×10−1 M of La3+ with a Nernstian slope of 20.5±1.0 mV per decade of La3+ activity. The response time of the sensor is <15 s and the membrane can be used over a period of 5 months with good reproducibility. The proposed electrode can be used in a wide pH range from 3.0 to 7.0 and demonstrates good discriminating power over a number of monovalent, divalent, and trivalent cations. This can be used in non-aqueous medium having up to 25% (v/v) non-aqueous content. The sensor has been used successfully as an indicator electrode in the potentiometric titration of lanthanum(III) ions against EDTA and for the determination of La3+ in binary mixtures.