1. Purpose

To define the procedure for calibration of the Slit-to-Agar Air Sampler used for environmental monitoring to ensure accurate measurement of microbial air contamination.

2. Scope

This SOP applies to all STA air samplers used in microbiology or cleanroom environments within the facility.

3. Responsibility

• QC/Microbiology Analyst: Perform calibration as per procedure and record results.

• QC Supervisor: Verify and review calibration data.

• QA Department: Ensure compliance with GMP and approve calibration reports.

• Engineering/Service Personnel (if external): Perform annual calibration and maintenance.

4. Materials & Equipment

• Slit-to-Agar Air Sampler

• Certified Calibrated Flowmeter (traceable to national standards)

• Stopwatch / Timer

• Sterile agar plates (TSA/SDA as applicable)

• Calibration certificate template / logbook

• Cleanroom wipes and disinfectant

5. Procedure

5.1 Pre-Calibration Checks

1. Verify sampler is clean and free from dust/contamination.

2. Ensure equipment ID and calibration due date label are intact.

3. Place sampler on a vibration-free surface in a controlled environment.

4. Verify agar plates are within expiry if used during calibration check.

5.2 Calibration of Air Flow Rate

1. Connect the calibrated external flowmeter to the air inlet of the STA sampler.

2. Switch on the sampler and set the flow to its nominal value (commonly 1 CFM / 28.3 LPM, as per pharmacopeia requirements).

3. Record the actual flow rate measured by the external flowmeter.

4. Repeat the measurement three times to ensure consistency.

5. If deviation is observed beyond acceptance criteria, adjust flow setting (if allowed) or label equipment as “Out of Calibration.”

5.3 Timer Verification

1. Set the sampler to run for a defined time (e.g., 1 minute).

2. Simultaneously start the stopwatch.

3. Compare actual run time with set time.

4. Acceptable tolerance: ±2 seconds.

5.4 Acceptance Criteria

• Flow rate: Within ±5% of set value (as per USP/Ph. Eur.).

• Timer accuracy: Within ±2 seconds.

• If results are out of limits, sampler shall not be used until recalibrated/serviced.

5.5 Post-Calibration

1. Record results in Calibration Logbook.

2. Affix “Calibrated” label with next due date.

3. If out of calibration, report to QC/QA for investigation and corrective action.

6. Frequency

• Internal Verification: Every 6 months.

• External Calibration by Qualified Agency: Annually (or as per manufacturer recommendation).

7. Precautions

• Perform calibration in controlled clean area.

• Handle equipment carefully to avoid mechanical shock.

• Use only certified calibration instruments.

• Do not operate sampler without agar plate during routine use (except calibration).

8. Documentation

• Calibration record/logbook with flow rate, timer accuracy, and analyst details.

• Certificate of calibration (for external service).

• Deviation report in case of failure.

9. References

• USP <1116> “Microbiological Control and Monitoring of Aseptic Processing Environments”

• Ph. Eur. 2.9.18 “Microbiological Monitoring of Cleanrooms and Controlled Environments”

• Manufacturer’s User Manual