Calibration in GxP Applications – PST/Rotronic RMS Solution

Calibration Procedure for Rotronic Monitoring System (RMS) Probes in a GxP Compliant Fridge

This procedure ensures traceable, accurate calibration of RMS temperature probes used in GxP-regulated environments, such as pharmaceutical storage, clinical trials, and biotech applications.

RMS will use the following vocabulary:

• As found: initial calibration as found value
• As left: as left calibration value after adjustment
• Reference: reference unit (device/probe) value
• UUT: unit (device/probe) under test (calibration)
• Error: difference between the reference value and UUT value
• Result: result of the calibration, either OK (pass) or Error (fail)

• Standard recommendation: Annually (every 12 months)
• Higher-risk applications (e.g., vaccines, biologics): Every 6 months or quarterly based on risk assessment. The risk assessment is the user’s responsibility.
• Real-time monitoring: If drift is observed, recalibrate sooner.

Required Equipment

• Reference unit: A high-accuracy, traceable ISO 17025-certified device/probe
• Using a device integrated into RMS will help reduce the human interaction and the measurement values can be taken directly from RMS.

• Calibration medium:
• Air calibration – Performed in a stable, controlled environment (inside the fridge or in a specific generator)
• Liquid calibration – Glycol buffer or distilled water to mimic the thermal response of stored products

• Calibration software: Calibrations can be done directly within the RMS software and the audit trail will be updated accordingly. Adjustments will also be documented within the audit trail. When calibrating directly within the RMS software the following details will be stored:
• Data of the calibration
• Equipment identification:
• Serial number of the unit under calibration
• ID of the unit under calibration
• Name of the unit under calibration

• Calibration type: as found or as left
• Tolerance for the calibration
• Serial number of the reference unit
• Information about the reference unit
• Environment where the unit was calibrated
• Calibration comments
• Reference value
• Unit under test value
• Error: difference between the reference value and unit under test value
• Result: automatic review of the error and tolerance difference
• User carrying out the calibration/adjustment, including name and signature
• The next calibration date can also be added to the RMS system and users can be notified when the next calibration is required.

• Documentation tools: RMS can generate calibration reports and service reports for traceability.

Calibration Procedure

• Review calibration history in RMS software and assess drift trends.
• Identify UUT location in the fridge. If multiple UUTs are used, verify their positions. It is crucial that the UUTs are returned to the same location in the fridge after calibration.
• Update RMS with the following data:
• Tolerance for the measurement
• Reference information
• Environment information

• Place the reference and the UUT together within the defined environment (e.g., generator or fridge):
• In a liquid buffer (preferred) or air
• As close as possible to each other to minimize environmental differences
• Allow at least 10-15 minutes for temperature stabilization
• Record readings from both the UUT and the reference directly within the RMS software

• RMS will automatically calculate the error between the UUT and the reference unit. Example: If RMS reads 4.2°C and the reference thermometer reads 4.0°C, the error is +0.2°C.
• Within RMS, we recommend carrying out the two calibration points before carrying out any adjustments.
• Once the two calibration points have been taken, the UUT can be adjusted to correct the error. This ensures that future readings align with the traceable reference.

• Once the UUT has been adjusted, the ‘as left’ calibrations need to be carried out for the same two points.
• If the deviation exceeds your defined tolerance, recalibrate or replace the probe.

Post-Calibration Documentation

• The results are automatically stored within the RMS system.
• Store records for audit purposes as per GxP regulations (FDA 21 CFR Part 11, EU Annex 11).
• The calibration documents can be reviewed directly within the RMS software.

Corrective Actions for Out-of-Tolerance Probes

• If deviation exceeds tolerance, perform a risk assessment on stored products.
• Investigate possible causes (e.g., sensor drift or handling issues).
• If deviation is significant, replace or send the probe for recalibration.

Additional Notes for RMS Users

• Audit trail compliance: Ensure all calibration activities are logged digitally.
• Reminders: Ensure that all users are aware of the next calibration date.

Related Blog Posts

Related Content