Lead(II) and copper(II) ion-selective electrodes based on two heterocyclic compounds

摘要

In this paper, two nitrogen, sulphur or oxygen containing heterocyclic compounds were used as ionophores in ion-selective electrodes. In these two ion-selective electrodes, 2,6-di(5-methyl-1,3,4-oxadiazol-5-yl)pyridine (DMOP) gives the best Pb~(2+) sensitivity and 2,5-di(2'-methylpyridinethio) thiadiazole (DPTD) gives the best sensitivity for Cu~(2+). These electrodes are composed of KTpClPB as anion excluder and DOS as plasticizer. The two membrane electrodes show Nernstian or near-Nernstian response towards Pb~(2+) or Cu~(2+) (29.3 and 27.3 mV/decade, respectively) over the concentration range 10~(-5)～10~(-2) and 10 ~(-6)～10~(-3) M, respectively. The response time was less than 20 sec and a good reproducibility over a period of 2 months was observed. The electrodes exhibited good selectivities over a number of alkali, alkaline earth and transition metal ions. The proposed electrodes have also been used for the direct determination of Pb~(2+) and Cu~(2+) ions in real samples.