Calibration records are critical quality records kept by pharmaceutical manufacturers. A long list of measuring instruments is frequently used in making decisions which can impact product quality.
A calibration certificate will not necessarily ensure that the entire calibration system works as intended. The company needs to know what equipment was calibrated, with what standard, when it was done, who calibrated the equipment, the results of calibration and if the instrument met its specifications.
Calibration records can be crucial during inspections when an investigator follows a product or laboratory result back to the measuring equipment that generated it. A calibration record should be well-established enough that no personal memory is needed for the reconstruction of what the instrument endured.
Based on the apparatus, a calibration record may include:
Take for example the temperature sensor used for monitoring a pharmaceutical storage area. If the sensor reads 25°C but the real temperature varies significantly from this figure, the decisions made based on this figure will be wrong.
The same thing is true for:
Identification has to be analogous in all of the following:
The calibration label indicates the relevant information such as:
Instrument ID: BAL-025
Calibrated On: 15-Aug-2026
Next Due: 15-Aug-2027
Status: CALIBRATED
The label itself is not a replacement for the calibration records as it indicates the relevant information about the current situation while the rest of the information can be found in the complete records.
The calibration document must indicate the reference standards utilized.
For instance, if affecting the calibration of a temperature transmitter, the utilized reference thermometer must be recorded.
As-found results denote the condition of the instrument prior to any adjustment.
As-left results denote the condition of the instrument once it has completed adjustment, if any adjustment was made.
Note that this distinction is important, for adjustment of an instrument may bring it into tolerance even if it was previously operating beyond the acceptable limits.
If only a final result is ever recorded, then some important information about the past behavior of the instrument may be lost to the organization.
As-found conditions also allow us to evaluate whether previous readings could have been affected.
All criteria considered can include:
For instance, temperature sensor can have tolerances established at different calibration points and results can be shown as "PASSED" without showing the evaluations.
Some of the key aspects influencing calibration frequency may include:
Risk assessment may provide the necessary basis for the calibration program to be put in place. Instruments acting according to the historical data may need a different calibration frequency from instruments that drift.
All changes in calibration frequency need to be substantiated and carefully monitored.
Any company must establish the following:
For instance, if a scale used when producing active pharmaceutical constituents is outside of the limit, the investigation should involve all materials processed with the scale since the last successful calibration session.
Preventive maintenance is the entire process of keeping the equipment in good mechanical and operational condition. Therefore, a calibration program should not be thought to substitute for preventive maintenance.
Whenever applicable, calibration and maintenance records should be connected together so that the history of the equipment can be examined in its entirety.
Such systems can ensure:
When systems are used for GMP operations they should be qualified or validated to use for the intended purpose.
1. Assign unique identification to each instrument.
2. Define the requirements for calibrations based on their intended use and risks.
3. Make use of approved procedures related to calibrations.
4. Record the actual results obtained during calibration.
5. Maintain traceability of the reference standard.
6. When applicable, document as-found and as-left conditions.
7. Keep track of the status of calibration at the place of use.
8. Investigate any non-compliance.
9. Evaluate the possible effects if any on previous measurements.
10. Identify the trends of the calibration performance and the occurrence of malfunctioning over time.
Regular analysis of the calibration information may disclose the instruments which either drift always in one direction or require regular recalibration.
The significance of calibration records comes from the fact that they provide proof that the measuring and control equipment used by the pharmaceutical company meets its intended use. However, the significance of calibration records is not limited to providing information that a certain instrument was calibrated on a certain date.
A good record must provide information about the identification of the instrument, the procedure used, the reference standards applied, the measurement results, the acceptance criteria, and the final calibration results. If an instrument is found not to be calibrated, the company has to analyze the possibility that all measurements made earlier and all products manufactured could have been influenced by the erroneous readings.
Calibrations programs having quality-system view treat the data related to calibrations as the source of information about the processes. The data can demonstrate that there was the instrument drift, the repeated failures of the instrument, the problematic calibration intervals, and problems with the reliability of the equipment.
A calibration certificate will not necessarily ensure that the entire calibration system works as intended. The company needs to know what equipment was calibrated, with what standard, when it was done, who calibrated the equipment, the results of calibration and if the instrument met its specifications.
Calibration records can be crucial during inspections when an investigator follows a product or laboratory result back to the measuring equipment that generated it. A calibration record should be well-established enough that no personal memory is needed for the reconstruction of what the instrument endured.
What are Calibration Records?
Calibration records are proof of the calibration process carried out on various measurement and testing equipment.Based on the apparatus, a calibration record may include:
- Identification number of the apparatus
- Description of the instrument
- Location
- Calibration date
- Expiry date
- Calibration method
- Standard used for calibration
- Identification of the standard
- Calibration status of the standard
- Calibration points
- As found results
- As left results
- Acceptance criteria
- Adjustment information
- Calibration results
- Environmental conditions if appropriate
- Name and signature of the calibrator
- Approval by the reviewer
Importance of Calibration Records
Calibration process ensures that measurement equipment gives reliable figures.Take for example the temperature sensor used for monitoring a pharmaceutical storage area. If the sensor reads 25°C but the real temperature varies significantly from this figure, the decisions made based on this figure will be wrong.
The same thing is true for:
- Weighers
- Dissolution cells
- HPLC system
- Temperature sensors for autoclave
- Pressure meters
- Differential pressure transducers
- pH measuring meters
- Devices for measurement of conductivity
- Temperature mapping devices
Identification and Calibration Status
All instruments that are critical for measurement should be identifiable by means of a unique number.Identification has to be analogous in all of the following:
- Equipment
- Calibration label
- Calibration record
- Maintenance documents
- SOPs
- Qualification documents for equipment
- Electronic systems
The calibration label indicates the relevant information such as:
Instrument ID: BAL-025
Calibrated On: 15-Aug-2026
Next Due: 15-Aug-2027
Status: CALIBRATED
The label itself is not a replacement for the calibration records as it indicates the relevant information about the current situation while the rest of the information can be found in the complete records.
Reference Standards and Traceability
Calibration should take place with the help of standards controlled properly and traceable to the accepted reference standards for measurements where applicable.The calibration document must indicate the reference standards utilized.
For instance, if affecting the calibration of a temperature transmitter, the utilized reference thermometer must be recorded.
- Reference thermometer ID
- Calibration status
- Certificate number
- Calibration time limit
- Relevant uncertainty or accuracy information if required
As-found and As-left Results
When we look at what might be the most useful method to document calibration, a clear distinction between as-found data and as-left data is one of the very major things.As-found results denote the condition of the instrument prior to any adjustment.
As-left results denote the condition of the instrument once it has completed adjustment, if any adjustment was made.
Note that this distinction is important, for adjustment of an instrument may bring it into tolerance even if it was previously operating beyond the acceptable limits.
If only a final result is ever recorded, then some important information about the past behavior of the instrument may be lost to the organization.
As-found conditions also allow us to evaluate whether previous readings could have been affected.
Calibration Acceptance Criteria
The criteria for acceptance must be predefined and supported by scientific proofs.All criteria considered can include:
- Specifications by the manufacturer
- Requirements by pharmacopoeia
- Requirements by process
- Qualification of equipment
- Analytical method requirements
- Internal specifications
- Risk evaluation
For instance, temperature sensor can have tolerances established at different calibration points and results can be shown as "PASSED" without showing the evaluations.
Calibration Frequency
The intervals for calibration must be set up based on scientific and historical evidence.Some of the key aspects influencing calibration frequency may include:
- Importance of the instrument
- Historical calibration results
- Frequency of use
- Environmental conditions
- Manufacturer's instructions
- Instrument technology
- Impact on product quality
Risk assessment may provide the necessary basis for the calibration program to be put in place. Instruments acting according to the historical data may need a different calibration frequency from instruments that drift.
All changes in calibration frequency need to be substantiated and carefully monitored.
Handling Calibration Failures
An equipment that is discovered outside of the limits of accuracy should not be approached as a singular maintenance problem.Any company must establish the following:
- How long the equipment has been out of calibration.
- What materials and products were handled.
- What data were collected during the use of this equipment.
- Whether previous records are still valid.
- Whether another equipment was influenced by the incident.
- Whether there is a need for investigation.
For instance, if a scale used when producing active pharmaceutical constituents is outside of the limit, the investigation should involve all materials processed with the scale since the last successful calibration session.
Calibration and Preventive Maintenance
Although calibration and preventive maintenance are related activities, they are different. Calibration is the process of determining if an instrument is performing within the specified limits of measurement or not.Preventive maintenance is the entire process of keeping the equipment in good mechanical and operational condition. Therefore, a calibration program should not be thought to substitute for preventive maintenance.
Whenever applicable, calibration and maintenance records should be connected together so that the history of the equipment can be examined in its entirety.
Electronic Calibration Records
It is common in many pharmaceutical plants to use a computer management system or other electronic systems for calibration.Such systems can ensure:
- Automated notifications of due dates
- Calibration plans
- Instrument history
- Certificate management
- Approval processes
- Alerts of overdue items
- Condition of equipment
- Trends
When systems are used for GMP operations they should be qualified or validated to use for the intended purpose.
Common Calibration Record Deficiencies
Some of the common shortcomings are:- Lack of calibration results.
- Only "Pass" is recorded without any details.
- No evidence of traceability to calibration standards.
- The results prior to calibration are missing.
- Calibration performed after the scheduled date without documented assessment.
- Calibration tags not matching the calibration records.
- Signatures and approvals are incomplete.
- Calibration certificates not being controlled properly.
- Instruments that are out of tolerance not being investigated properly.
- Previous measurements are not properly investigated in case of calibration failure.
Good Practices for Calibration Records
A good system of calibration records must:1. Assign unique identification to each instrument.
2. Define the requirements for calibrations based on their intended use and risks.
3. Make use of approved procedures related to calibrations.
4. Record the actual results obtained during calibration.
5. Maintain traceability of the reference standard.
6. When applicable, document as-found and as-left conditions.
7. Keep track of the status of calibration at the place of use.
8. Investigate any non-compliance.
9. Evaluate the possible effects if any on previous measurements.
10. Identify the trends of the calibration performance and the occurrence of malfunctioning over time.
Regular analysis of the calibration information may disclose the instruments which either drift always in one direction or require regular recalibration.
A good record must provide information about the identification of the instrument, the procedure used, the reference standards applied, the measurement results, the acceptance criteria, and the final calibration results. If an instrument is found not to be calibrated, the company has to analyze the possibility that all measurements made earlier and all products manufactured could have been influenced by the erroneous readings.
Calibrations programs having quality-system view treat the data related to calibrations as the source of information about the processes. The data can demonstrate that there was the instrument drift, the repeated failures of the instrument, the problematic calibration intervals, and problems with the reliability of the equipment.

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