Characterization of an ion sensitive field effect transistor and chloride ion selective electrodes for pH measurements in seawater.
Anal Chem
; 86(22): 11189-95, 2014 Nov 18.
Article
em En
| MEDLINE
| ID: mdl-25325617
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.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Água do Mar
/
Transistores Eletrônicos
/
Cloretos
Tipo de estudo:
Diagnostic_studies
Idioma:
En
Ano de publicação:
2014
Tipo de documento:
Article