Use of a flow-injection system in the evaluation of the characteristic behavior of neutral carriers in lithium ion-selective electrodes

✍ Scribed by Robert Y Xie; Victor P.Y Gadzekpo; Azza M Kadry; Yehia A Ibrahim; Jaromir Růžička; Gary D Christian

• Book ID: 104100745
• Publisher: Elsevier Science
• Year: 1986
• Tongue: English
• Weight: 745 KB
• Volume: 184
• Category: Article
• ISSN: 0003-2670
• DOI: 10.1016/s0003-2670(00)86490-9

✦ Synopsis

A flow-injection system based on microconduits is used to investigate electrode characteristics such as selectivity, detection limit, and response and equilibrium times of the new ionophore, N,N,N',N'-tetraisobutyl-5,5-dimethyl-3,7-dioxanonane diamide, in lithium ion-selective electrodes. These characteristics were compared with those of the ionophore N,N'-diheptyl-N, N',5,5-tetramethyl-3,7-dioxanone diamide. The new ionophore has superior detection limits and shorter response and equilibrium time, but the other exhibits better selectivity for lithium with respect to sodium. Values of Kz', for the new ionophore vary from 0.0450 to 0.566, depending on the methods of measurement and solution conditions. This phenomenon is discussed. Stop-flow experiments effectively demonstrated the response and equilibrium time differences between these two ionophore membranes.

Flow-injection techniques have found wide application in several areas

of analytical chemistry. In the area of ion-selective electrodes, they offer advantages of increased sensitivity, decreased chemical and mechanical interferences, fast response time and very good reproducibility of results [l] . Flow-injection techniques with potentiometric detection have been applied to the determination of ions in blood serum [2--41. Few studies have used this technique to characterize electrode behavior. This paper describes an investigation of the characteristic behavior of a new compound, N,N,N',N'tetraisobutyl-5,5dimethyl-3,7dioxanonane diamide (ionophore l), as the ionophore in a lithium ion-selective electrode. Its behavior is compared to that of the previously reported N,N'-diheptyl-N,N',-5,5-tetramethyl-3,7dioxanonane diamide (ionophore 2) by using flow-injection measurements. Zhukov et al. [5] prepared several lipophilic diamides and investigated