PPb Level Monitoring of Dy(III) Ions by a Highly Sensitive and Selective Dy(III) Sensor Based on a New Asymmetrical Schiff's Base

摘要

A Dy(III) ion-selective membrane sensor has been fabricated from polyvinyl chloride (PVC) matrix membrane containing a new asymmetrical Schiff's base [(E)-N-(2-hydroxybenzylidene)benzohydraide] or BBH as a neutral carrier,sodium tetraphe-nyl borate (NaTPB) as an anionic excluder and nitrobenzene (NB) as a plasticizing solvent mediator.The membrane sensor displays linear potential response in the concentration range of 1.0 x 10~(-2)-1.0 x 10~(-6) M of Dy(III).The electrode exhibits a nice Nernstian slope of 20.1+-0.8 mV/decade in the pH range of 3.0-8.0.The sensor has a relatively short response time in whole concentration ranges (<20 s).The detection limit of the proposed sensor is 8.0 x 10~(-7) M (approx 128 ng/mL),and it can be used over a period of six weeks.The selectivity of the proposed sensor with respect to other cations,(alkali,alkaline earth,transition and heavy metal ions) and especially lanthanid ions,is excellent.The practical utility of the sensor has been demonstrated by using it as an indicator electrode in the potentiometric titration of Dy(III) with EDTA.