Comparative Study of Poly(Vinyl Chloride) Based Polymeric Membrane Sensors for the Determination of Erbium (III)

The three chelates 1,5-bis(o-aminobenzoate)-3-thiapentane (l1), 1,5-bis(omethoxybenzoate)-3-thiapentane (l2), 1,5-bis(o-chlorobenzoate)-3-thiapentane (l3) havebeen synthesized and explored as a neutral ionophores for preparing poly(vinyl chloride)based membrane sensors selective to er3+. the addition of sodiumtetraphenylborate andvarious plasticizers, viz., o-npoe, tbp, dbbp, tep and dos has been found tosubstantially improve the performance of the sensor. the best performance was obtained withthe sensor no.6 having membrane of ionophore (l2) with composition pvc: o-npoe:ionophore (l2): natpb (%w/w) of 35:56:2:7. this sensor exhibits nernstian response withslope 22.1±0.3 mv decade-1 of activity in concentration range 3.0×10-9 to 1.0×10-2 m er3+,performs satisfactorily over wide ph range (1.5-6.7), with a fast response time (8 s). thesensor was also found to work satisfactorily in partially non-aqueous media up to 20%content of methanol, ethanol or acetone and could be used for a period of 5 months withoutany change in response characteristics. the er3+ selective sensor was used as an indicatorelectrode for the titration of 25 ml 1×10-3 m edta solution and for the determination of er3+ion in different synthetic samples. the proposed electrode no. 6 was also used for thedetermination of fluoride ion in two mouth wash sample.