Why can't ORP reference solutions and pH reference solutions be used interchangeably for calibration?
pH/ORP sensor calibration differences.
ORP reference solutions and pH buffers are designed specifically for either ORP or pH, but are not interchangeable. ORP sensors by definition use the oxidation-reduction potential of ORP reference solutions, measured in mV. pH sensors by definition use the hydrogen ion concentration to generate a mV signal that is directly related the pH of the sample or buffer solution.