Abstract: A pH sensor comprising pH sensing instrumentation, reference sensing instrumentation, an electrochemical junction, and a pH determination unit. The pH sensing instrumentation comprises a pH fluid, a pH fluid chamber, a pH sensing chamber, and a measuring electrode extending through the pH fluid chamber and comprising a tip that resides in the pH sensing chamber. The reference sensing instrumentation comprises a reference fluid, a reference chamber filled with the reference fluid, a reference electrode immersed in the reference fluid, and monitoring instrumentation. The monitoring instrumentation comprises a monitoring fluid, a monitoring fluid chamber, a monitoring sensing chamber filled with the monitoring fluid, and a monitoring electrode extending through the monitoring fluid chamber and comprising a tip that resides in the monitoring sensing chamber. The monitoring fluid chamber and the monitoring sensing chamber are immersed in the reference fluid.