In-process verification of calibration status of ph probes

An automated system for low pH viral inactivation, comprising:

• a first vessel;
• a second vessel;
• a first pH probe associated with the first vessel and configured to measure the pH of contents of the first vessel;
• a source of a fluid known or suspected to contain at least one enveloped virus to be transferred to the first vessel;
• an acid pump configured to pump acid into the first vessel after the fluid is transferred into the first vessel and configured to cease pumping acid into the first vessel responsive to the first pH probe measuring a first pH value that is within a tolerance band of a target pH value for viral inactivation;
• a transfer pump configured to pump the acidified pool from the first vessel to the second vessel responsive to the first pH probe measuring the first pH value that is below the threshold pH value for viral inactivation, and responsive to the acid pump ceasing to pump acid into the first vessel;
• a first buffer pump configured to pump a first equilibration buffer, having a first known pH value, into the first vessel responsive to the entire acidified pool being pumped out of the first vessel;
• and
• an alert generator configured to:
• compare a second pH value, measured by the first pH probe after the first equilibration buffer is pumped into the first vessel, to the first known pH value of the first equilibration buffer;
• determine whether the second pH value measured by the first pH probe is different from the first known pH value of the first equilibration buffer by greater than a threshold pH value;
• and
• generate a first alert responsive to the second pH value measured by the first pH probe being different from the first known pH of the first equilibration buffer by greater than the threshold pH value.