Instrument: pH Sensor
An instrument that measures the hydrogen ion activity in solutions.
The overall concentration of hydrogen ions is inversely related to its pH. The pH scale ranges from 0 to 14 and indicates whether acidic (more H+) or basic (less H+).
pH data were recorded using Cole Parmer 350 pH/ORP controller units and Oakton epoxy body pH electrodes (UX-35801-00) calibrated weekly to a precision of 0.01 pH unit using NBS buffers. Output signals (4-20 mA) from the pH controllers were recorded at 10 minute intervals using the same NI data logger system and LabView software system used for the temperature data.