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RECORD NUMBER: 3 OF 329

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
Holdings
Library Call Number Additional Info Location Last
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Status
NTIS  PB88-196308 Most EPA libraries have a fiche copy filed under the call number shown. Check with individual libraries about paper copy. NTIS 09/04/1988
Collation 8p
Abstract
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.)