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Frank Gray


Calibration Documentation 101

Back to basics: Common sense tactics to put quality back into your calibration

Published: Monday, December 15, 2008 - 10:52

In sports, it's always the fundamentals that your coaches emphasize, like the techniques that you first learn when you’re starting to play baseball—how to hold the ball properly, how to stand and hold a bat, or how to field a grounder. The basics about the sport, if performed perfectly, yield a positive outcome and add to the whole game experience. It's the same with calibrations. With all the new technology and advancements that come with calibration tracking and performance, we tend to overlook the basics, which in the long run, may lead to an unfavorable outcome during an audit.
Calibration documentation is a function of your quality unit. Engineering, metrology team, vendor, or production personnel may perform the task of calibration, but the documentation review, verification, and follow-up is a quality function and should be treated as such. Whether you use upscale calibration software that complies with Food and Drug Administration (FDA) 21 CFR part 11, or a paper documentation trail, your systems still may seem to lack the required quality functions to keep the systems compliant. Why is it that during an audit, the auditors always find a documentation or traceability issue within your calibrations? It's those little issues that make it seem like you have no control of your systems.

What should you do to ensure compliance with your calibration system? Get your quality department involved and go back to the basics.

Review, verify, follow up, and comply
It happens all the time. You have a calibration company come in and perform calibrations of your equipment, they hand you calibration certificates and then you file them in a cabinet until the next time they come in to perform calibrations again. Where are the controls, compliance, and basic checks and balances?

Calibration is a quality function and should be treated as such. Although the actual calibrations may take place using engineers, an internal metrology team, or a contract metrologist, it’s still the quality function to ensure compliance with all data generation and any form of data documentation. Regardless of who provides the calibration services, the manufacturing company is responsible for reviewing, managing, recording, and ensuring calibration compliance.

All data generated need to be reviewed to ensure compliance to all aspects of accuracy, precision, and documentation. Once the information is reviewed, then it should be reviewed and verified against procedures for acceptance criteria, compliance to documentation, and compliance to accurate data entry. All data generated electronically should coincide with any paper documentation. In addition, any required investigation for equipment that was found out of tolerance needs to be performed. Once the data has been verified, a follow-up should be performed to ensure total accuracy in all aspects of the performance calibration, documentation, and the data capture.

Follow up is an important aspect of this system. Any investigation concerning out-of-tolerances, incorrect labels, incorrect data recorded, or incorrect data entry need to be addressed and taken care of in a timely manner. The follow-up ensures that all aspects of the data-review process have been verified and addressed. Most errors are overlooked and missed because a follow-up hasn’t been performed.

Labeling your equipment
One of the most missed aspects of calibration is the identification requirement of your equipment.

Most equipment has serial and model numbers, and some facilities will use the serial number as the identification (ID) number. This is fine, just as long as your equipment ID label has the serial number written on it. The label is classified as being part of the calibration records. At a minimum, the label should include the following: equipment ID number, calibration-performed date, next calibration due date, and initials of the person who performed the calibration. The ID should be displayed on or near the equipment and be readily available to the personnel using such equipment and to the individuals responsible for calibrating the equipment. Remember, the identification is a requirement used during the production or testing of a product to show the specific equipment used in the testing or production of a batch. The quality function should ensure all equipment that requires calibration have a calibration ID label with the required information.

To calibrate a piece of equipment you usually need another piece of equipment or solution to perform the calibration. This piece of equipment or solution would be classified as a "standard." The standard used for the inspection, measuring or testing of equipment should be traceable to national or international standards. Standards should always be documented on the calibration form or certificate along with any National Institute of Standards and Technology (NIST) or other traceable references. Whether you perform calibrations internally or outsource to a contractor, it’s important to document all the standards being used for your calibration records and compliance. The equipment being calibrated has to be within a certain precision and accuracy to meet operation requirements. The standards being used must also maintain their precision and accuracy to accurately perform adjustments to the equipment being calibrated with very little margin of error. The quality group should also maintain the documentation for the standards. Your equipment calibrations are only as good as the standards being used to perform them. If your calibrations are outsourced, then I recommend you request calibration documentation for the standards or, at a minimum, NIST-traceable reference numbers

Standard operating procedures (SOPs):
Calibrations of equipment SOPs are essential and needed if your quality group is to perform verifications of accuracy, precision, and compliance.

How will the calibration be performed? How often does the equipment require calibration? What will be the nominal values tested? What is the range of acceptance? Documentation of "as found" (the values in which the instrument was found at each testing point) and "as left" (the values in which the instrument was adjusted and left at each testing point). What standards will be used? What happens if the "as found" acceptance is out of range?  

All of these are critical for any calibration procedure. Your facility must establish and maintain SOPs to ensure that calibrated equipment is routinely calibrated, inspected, and maintained. The due dates (frequency) are usually established by the equipment manufacturer. If not, then the frequency should be based on your daily usage and the need for precision and accuracy. (Note: Some frequency and other instrument parameters may also be established during any required validations)

These activities in your processes should include provisions for handling, storage, and preservation to ensure the fitness and accuracy of a device. Your procedures should also include specific directions and limits for accuracy and precision and what investigations need to be performed to evaluate whether there were any adverse effects on the device's quality or any product produced using the equipment. In addition, documentation should include any remedial actions needed to reestablish the limit. It’s extremely important to know what your "as found" values were when performing your calibrations. Even though you may have to make adjustments to place the equipment back into the optimal operational range, it’s important to record these "as found" values as well as the "as left." If the "as found" value isn’t within the acceptable working ranges, then an out-of-tolerance (OOT) investigation must be performed.

Subclause b of FDA 21 CFR 820.7 states: "When accuracy and/or precision limits are not met, there should be provisions for remedial action to reestablish the limits and to evaluate whether there was any adverse effects on the device quality. These actions shall be documented." A thorough investigation on what effect the OOT device may have had since the last calibration on the quality of the manufactured product that was associated with the OOT device usage during the time between the last calibration and the recent must be performed. The equipment may be able to be placed back into acceptable range, the equipment may have to be replaced because it can’t go back into usable range, or an evaluation of the frequency or performance of the equipment may need to be reevaluated.

Trilogy: Label, paper documentation, database documentation
One of the biggest reasons for receiving an audit observation is that your various pieces of documentation don't correspond with each other. The equipment ID number, the person performing the calibration, the date of calibration, and the date of the next calibration should all coincide with the label on the equipment, the paper documentation in which the data was recorded, and the database in which the data is being kept. The person entering the data may make a mistake, often inputting a wrong value. We’re all human and these errors do occur. Sometimes your calibration team will inadvertently put a wrong due date on the label or certificate. That's why you need a quality function to constantly review recent calibrations, not only for acceptance criteria but also for documentation accuracy. In addition, ensuring that all calibration records are reasonably accessible to responsible officials when needed is important. There’s nothing worse than having an auditor ask for calibration records and the records can’t be found.

The little steps that we sometimes overlook can cause larger compliance problems down the line. The quality aspect shouldn’t be overlooked when it comes to compliance of your calibration system. You may have all the elaborate calibration tracking databases and software, but without a quality department's involvement to ensure compliance you might as well just be asking for trouble.

If you go back to the basics and make sure your quality functions are involved in your calibration review, verification, and follow-up, you can eliminate the task of correcting a faulty system later.

Copyright John Wiley & Sons Inc. Published with permission. Previously published in Pharmaceutical Formulation & Quality, September 2006, www.pharmaquality.com


About The Author

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Frank Gray

Frank Gray is an ASQ-certified quality auditor/lead quality investigator for Cardinal Health of Raleigh, North Carolina. Reach him at (919) 327-5518 or e-mail him at Frank.Gray@cardinal.com.