POTENSIOMETRISK ELEKTRODE OG ANVENDELSE DERAV

摘要

A potentiometric electrode includes an enclosure 22 containing an internal electrolyte 26 which couples the sensing area (eg membrane 24) to a lead 28 of electrically conductive material such as a noble metal inert to the electrolyte; the electrolyte comprising a thermodynamically reversible redox couple having a large exchange current (>/= 10<-6> amp/cm<2>). Examples of such redox couples are: 2e<-> + I3<-> &rang& 3I<-> e<-> + Fe<3+> &rang& Fe<2+> e<-> + Fe(CN)6<3-> &rang& Fe(CN)6<4-> 2e<-> + Br2 &rang& 2Br<-> This construction substantially improving the response time of the electrode to changes in ambient temperature. For ion-sensitive electrodes with internal buffers, the redox couple can be selected so that its temperature coefficient ( DELTA E/ DELTA T) is the inverse of the temperature coefficient of the buffer, thereby rendering the electrode substantially temperature insensitive.