Aluminum(III) selective potentiometric sensor based on morin in poly(vinyl chloride) matrix

Abstract

Al 3+ selective sensor has been fabricated from poly(vinyl chloride) (PVC) matrix membranes containing neutral carrier morin as ionophore. Best performance was exhibited by the membrane having composition as morin:PVC:sodium tetraphenyl borate:tri- n-butylphosphate in the ratio 5:150:5:150 (w/w, mg). This membrane worked well over a wide activity range of 5.0 × 10 −7 to 1.0 × 10 −1 M of Al 3+ with a Nernstian slope of 19.7 ± 0.1 mV/decade of Al 3+ activity and a limit of detection 3.2 × 10 −7 M. The response time of the sensor is ∼5 s and membrane could be used over a period of 2 months with good reproducibility. The proposed sensor works well over a pH range (3.5–5.0) and demonstrates good discriminating power over a number of mono-, di- and trivalent cations. The sensor can also be used in partially non-aqueous media having up to 20% (v/v) methanol, ethanol or acetone content with no significant change in the value of slope or working activity range. The sensor has also been used in the potentiometric titration of Al 3+ with EDTA and for its determination in zinc plating mud and red mud.