Comparative study of Ag(I)selective poly(vinyl chloride)membrane sensors based on newly developed Schiff-base lariat ethers derived from 4,13-diaza-18-crown-6

摘要

The six Schiff-base lariat ether chelates based on 4,13-diaza-18-crown ether,have been synthesized and explored as a neutral ionophores for preparing poly(vinyl chloride)based membrane sensors selective to silver(I).The addition of potassium tetrakis(4-chlorophenyl)borate and various plasticizers,viz.,o-NPOE,DBP,DBBP,DOP and CN has been found to substantially improve the performance of the sensors.The best performance was obtained with the sensor no.5 having membrane of chelate(A6)with composition(w/w)chelate(2.8%):PVC(45.7%):o-NPOE(48.6%):KTpClPB(2.8%).This sensor exhibits Nernstian response with slope 59.3 mV/decade of activity in the concentration range 5.6 X 10~(-8)-1.0 X 10~(-1)M Ag(l),performs satisfactorily over wide pH range of(3.0-8.0)with a fast response time(12 s).The sensor was also found to work satisfactorily in partially non-aqueous media up to 25%(v/v)content of acetonitrile,methanol or ethanol and can tolerate the concentration 1.0 X 10~(-2)M of ionic(SDS,TBC)and nonionic(Triton X-100)surfactants.The proposed sensor can be used over a period of 4 months without significant drift in potentials.The response of the sensor was highly selective to Ag~+ over a large number of cations and it could therefore be used for Ag~+ estimation in blood of occupationally exposed persons.