SYMPOSIA PAPER Published: 01 January 1986

A Simple Method to Measure pH Accurately in Acid Rain Samples


Conventional pH electrodes, which are designed to function in high-conductivity solutions, show slow and erratic response in pure water samples such as acid precipitation. Increasing conductivity without shifting pH solves the measurement problem. This method correctly measures pH in low conductivity solutions, using a Ross combination pH electrode, after the addition of a small amount of potassium chloride (KCl) solution to the sample. The Ross electrode, with its unique internal redox system, is chosen since it eliminates problems associated with temperature and because the precision and accuracy of data obtained in preliminary testing with it were comparable to those obtained with the standard hydrogen electrode. KCl addition to samples does not alter the pH significantly.

Author Information

Boyle, PF
Orion Research, Inc., Cambridge, MA
Ross, JW
Orion Research, Inc., Cambridge, MA
Synnott, JC
Orion Research, Inc., Cambridge, MA
James, CL
Orion Research, Inc., Cambridge, MA
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Developed by Committee: D19
Pages: 98–106
DOI: 10.1520/STP18456S
ISBN-EB: 978-0-8031-4990-8
ISBN-13: 978-0-8031-0492-1