Record Display for the EPA National Library Catalog


OLS Field Name OLS Field Data
Main Title Accuracy of Ross pH Combination Electrodes in Dilute Sulphuric Acid Standards.
Author Metcalf, R. C. ;
CORP Author Lockheed-EMSCO, Las Vegas, NV.;Environmental Monitoring Systems Lab., Las Vegas, NV.
Year Published 1987
Report Number EPA-68-03-3249; EPA/600/J-87/327;
Stock Number PB88-196308
Additional Subjects pH ; Sulfuric acid ; Electrodes ; Water pollution ; Chemical analysis ; Electrochemistry ; Environmental tests ; Reprints ; Acid rain ; Environmental monitoring
Library Call Number Additional Info Location Last
NTIS  PB88-196308 Most EPA libraries have a fiche copy filed under the call number shown. Check with individual libraries about paper copy. 09/04/1988
Collation 8p
The mean observed pH of a 5.00 plus or minus 0.05 x 0.00001 M H2504 solution was 4.06 plus or minus 0.05 (2s) for 485 pH measurements by seven different operators, using nine Orion Ross Model 81-94b pH combination electrodes and four different pH meters over 8 weeks. Traditional methods using activity coefficients give a pH of 4.005 for this solution and the liquid junction potential error, yields a calculated pH for this standard of 4.030. The difference between the calculated pH, corrected by a larger residual liquid junction potential error than was calculated for this electrode with the currently available methods. Consequently, the assumption of a negligible residual junction potential error in future pH measurements of dilute acid standards is subject to question in accurate work. Further progress in the field seems limited by the non-availability of technological innovations which provide highly reproducible liquid junction potential errors or minimize temperature equilibration errors in pH probes. (Copyright (c) Analyst, November 1987, Vol. 112.)