高分子支持膜シュウ酸イオン選択性電極の試作とその性能第2報

概要

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Three kinds of quaternry ammonium salts with long alkyl groups having 8〜14 carbon atoms were applied to C_2O_4^<2->-ISEs as sensing materials and the electrochemical charactristics were studied. The three C_2O_4^<2->-ISEs had good linearties (10^<-4.5>〜10^<-1.5> moldm^<-3>), high Nernst slopes (-35〜42 mV/decade) and response time (<60s). The C_2O_4^<2->-ISEs based on quaternary ammonium salts affects that the effect of plasticizer (o-nitrophenyloctyl ether, NPOE) and for selectivity. On the other hand, preparation and characterization of oxalate ion selective field effect transistor (ISFET) electrodes were performed by use of conventional field effect transistor. It was found that the linear response range of the the ISFET electrode was from 10^<-5> moldm^<-3> to 10^<-1> moldm^<-3> for oxalate ion activity. The selectivity coefficient was so almost the same as that of the commercial ion selective electrode. The ion-sensing membrane containg PVC and quaternary ammonium salts could be continuously used for less than 4 weeks. The slope of the response curve was -42 mV/decade in the linearity. The analytical time used for electrode potential was less than 60 sec in concentration ranges of 10^<-4>〜10^<-1>M for oxalate ion and short response times (t_<90%> : generally, 5 sec). The proposed ISFET has some figure of merits such as easy and cheaper.