Application Note – GLP N.1 – Calibration interval for laboratory measurement instruments

Calibration interval for laboratory measurement instruments

Measuring equipment, test equipment should be calibrated at interval established with the intent of achieving and maintaining a desired level of accuracy and quality.

Calibration intervals

Measuring equipment should be calibrated as often as necessary to maintain prescribed accuracies.

Initial intervals for new equipment should be based on equipments manufacturer’s recommendation, engineering judgment, past equipment history or other appropriate sources.

Calibration intervals are normally established by the laboratory manager along with technicians and internal departments support.  Intervals are determined based on manufacturer’s recommendations, critically to each site process and /or usage, and industry standards. Calibration records play an important role in the establishment of calibration intervals and interval adjustments. 

Interval adjustment

Justification of interval adjustment can be made based on previously generated calibration results.  

If calibration records indicate frequent adjustments were made, the calibration interval can be shortened.  Calibration intervals can also be lengthened if the results of historical  calibration data reveal that the accuracy of the equipment or instrument will not be adversely affected.  

Interval adjustment documentation

Any calibration interval adjustment should be documented to include the equipment involved and the reason for the change.

Documentation of specified allowable tolerances for each instrument or group of similar instruments must be defined and documented prior of performing any calibration. Allowable tolerances can be defined in a SOP or an individual instrument calibration specification forms.