Characterization of an ion sensitive field effect transistor and chloride ion selective electrodes for pH measurements in seawater

TitleCharacterization of an ion sensitive field effect transistor and chloride ion selective electrodes for pH measurements in seawater
Publication TypeJournal Article
Year of Publication2014
AuthorsTakeshita Y, Martz TR, Johnson KS, Dickson AG
JournalAnalytical Chemistry
Volume86
Pagination11189-11195
Date Published2014/11
ISBN Number0003-2700
Abstract

Characterization of several potentiometric cells without a liquid junction has been carried out in universal buffer, aqueous HCl, and artificial seawater media. The electrodes studied include Ion Sensitive Field Effect Transistor (ISFET) pH electrodes, and Chloride-Ion Selective Electrodes (Cl-ISE) directly exposed to the solution. These electrodes were compared directly to the conventional hydrogen electrode and silver?silver chloride electrode in order to report the degree to which they obey ideal Nernstian laws. These data provide a foundation for operating the ISFET|Cl-ISE pair in seawater as a pH sensor. In order to obtain the highest quality pH measurements from this sensor, its response to changes in pH and salinity must be properly characterized. Our results indicate near-ideal Nernstian response for both electrodes over a wide range of pH (2?12) and Cl? molality (0.01?1). We conclude that the error due to sub-Nernstian response of the cell ISFET|seawater|Cl-ISE over the range of seawater pH and salinity is negligible (<0.0001 pH). The cross sensitivity of the Cl-ISE to Br? does not seem to be a significant source of error (<0.003 pH) in seawater media in the salinity range 20?35.

DOI10.1021/ac502631z
Short TitleAnal. Chem.
Student Publication: 
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