Strontium (II)-Selective Potentiometric Sensor Based on Ester Derivative of 4-tert-butylcalix(8)arene in PVC Matrix

Ajay K Jain,Vinod K Gupta,Jitendra R Raisoni

doi:10.3390/s40800115

Ajay K Jain, Vinod K Gupta + Show 1 more

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https://doi.org/10.3390/s40800115

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Abstract

Membranes of 4-tert-butylcalix(8)arene-octaacetic acid octaethyl ester (I) as an electroactive material, sodium tetraphenyl borate (NaTPB) as an anion excluder, and tri-n-butyl phosphate (TBP) as a solvent mediator in poly(vinyl chloride) (PVC) matrix have been tried for a strontium-selective sensor. The best performance was exhibited by the membrane having a composition 5:100:150:2 (I: PVC: TBP: NaTPB (w/w)). This sensor exhibits a good potentiometric response to Sr2+ over a wide concentration range (3.2 × 10 –5 –1.0 × 10 –1 M) with a Nernstian slope (30 mV/ decade). The response time of the sensor is 10 s and it has been used for a period of four months without any drift in potentials. The selectivity coefficient values are in the order of 0.01 for mono-, bi-, and trivalent cations which indicate a good selectivity for Sr2+ over a large number of cations. The useful pH range for the sensor was found to be 3-10 and it works well in mixtures with non-aqueous content up to 25 % (v/v). The sensor has been used as an indicator electrode in the potentiometric titration of Sr2+ against EDTA.

Highlights

Strontium is an important alkaline earth metal which finds application in production of glasses for colour television sets and ferrite magnets [1], in refining of zinc and added to tin and lead alloys for increasing hardness and durability [2]
It is seen that all plasticizers tend to improve the working concentration range, lower the response time and decrease the slope except DBBP, which increases it
A comparison of the performance characteristics of all the sensors clearly revealed that the sensor No 6 having a membrane with tri-n-butyl phosphate (TBP) plasticizer is the best as it exhibits the widest concentration range of 3.2 × 10 -5 - 1.0 × 10 -1 M, an almost Nernstian slope (30 mV/decade) and a minimum response time of 10 ± 1 s

Summary

Introduction

Strontium is an important alkaline earth metal which finds application in production of glasses for colour television sets and ferrite magnets [1], in refining of zinc and added to tin and lead alloys for increasing hardness and durability [2]. The results on the membranes of the derivative of 4-tert-butylcalix(8)arene are presented in this communication and show an improvement in selectivity, pH range and response time.

Results

Conclusion