Pipette Calibration SOP Template

1.Purpose

To confirm each pipette delivers volumes within its stated accuracy and precision so that dilutions, dosing and test results made with it stay reliable.

2.Scope

Applies to all single-channel and multichannel air-displacement pipettes used for testing or sample preparation. General instrument calibration is covered by the equipment calibration SOP.

Definitions

Gravimetric test

A calibration method that weighs dispensed water on an analytical balance to calculate the actual volume delivered.

Accuracy

How close the average delivered volume is to the target volume.

Precision (CV%)

How consistent repeated deliveries are with each other, expressed as a coefficient of variation.

3.Responsibilities

Lab Technician

Submits pipettes for calibration on schedule and reports suspected inaccuracy between calibrations.

Calibration Technician

Performs the gravimetric test, records results and applies the pass or fail label.

QA Manager

Sets tolerance criteria, reviews failed results and approves pipettes returning to service.

RACI matrix

R = Responsible, A = Accountable, C = Consulted, I = Informed

4.Materials and PPE

Materials, tools and systems

• →Analytical balance with calibration weights
• →Distilled or deionized water and thermometer
• →Calibration weights table for water density at temperature
• →Manufacturer-approved pipette tips
• →Calibration log or CMMS asset register
• →Pass or fail calibration labels

Personal protective equipment

• →Disposable nitrile gloves

5.Procedure

1. 5.1

   Check the calibration due date

   Lab Technician

   Check the label on the pipette or the CMMS asset register to confirm it is due, and remove it from the bench rotation for testing.

2. 5.2

   Record room conditions

   Calibration Technician

   Record the ambient temperature, humidity and barometric pressure in the calibration log, since these affect the water density calculation.

3. 5.3

   Inspect the pipette for damage

   Calibration Technician

   Check the shaft, tip cone, piston and seals for cracks, debris or wear, and clean the exterior before testing.

4. 5.4

   Perform a leak test

   Calibration Technician

   Attach a tip, draw up liquid, and hold the pipette vertically for 20 to 30 seconds to check for a falling meniscus, which indicates a seal leak.

   Warning: Do not proceed to gravimetric testing on a pipette that fails the leak test; tag it out of service.

5. 5.5

   Set the balance and tare

   Calibration Technician

   Place the weighing vessel on the analytical balance, close the draft shield, and tare the balance to zero before each dispense.

6. 5.6

   Dispense at minimum, mid and maximum volume

   Calibration Technician

   Dispense the target volume into the weighing vessel and record the weight for at least ten replicates at each of the minimum, mid and maximum volumes for that pipette.

   Checkpoint: At least ten replicate weighings are recorded at each test volume before calculations begin.

7. 5.7

   Calculate accuracy and precision

   Calibration Technician

   Convert each weight to volume using the water density at the recorded temperature, then calculate the mean volume, percent accuracy and percent CV for each test volume.

8. 5.8

   Compare results to tolerance

   Calibration Technician

   Compare the calculated accuracy and precision against the manufacturer's stated tolerance for that pipette model and volume.

9. 5.9

   Adjust or tag out of service if failing

   Calibration Technician

   If results are out of tolerance, adjust the pipette per the manufacturer's instructions and retest, or tag it out of service and arrange vendor service.

10. 5.10

    Apply the pass or fail label

    Calibration Technician

    Attach a label to the pipette showing the calibration date, due date, result and technician initials.

11. 5.11

    Log results and notify the owner

    Calibration Technician

    Enter the results into the calibration log or CMMS and notify the pipette's regular user that it is back in service or remains out for repair.

12. 5.12

    Review failure trends

    QA Manager

    Review pipettes with repeated failures or adjustments across calibration cycles and decide whether replacement is more cost-effective than continued repair.

6.Quality checks

• →Every calibration record shows at least ten replicates per tested volume.
• →Room temperature is recorded and used in the volume calculation.
• →Pipettes that fail the leak test are not gravimetrically tested until repaired.
• →Pass or fail labels match the result recorded in the calibration log.

7.Records

• →Calibration log or CMMS asset register
• →Gravimetric test data sheets
• →Pass or fail calibration labels
• →Vendor service records

8.KPIs

• →Percentage of pipettes calibrated on schedule
• →First-time pass rate on gravimetric testing
• →Number of pipettes requiring adjustment per cycle
• →Average pipette downtime for repair

9.Common mistakes

• →Skipping the leak test and going straight to gravimetric testing.
• →Not recording room temperature before calculating volumes.
• →Testing with tips that are not the manufacturer-approved brand for that pipette.
• →Using fewer than the required number of replicates per volume.

10.Revision history