Standard Operating Procedure (SOP)

Here is a comprehensive Standard Operating Procedure (SOP) for Calibration of Plunger Operated Pipette—commonly used in laboratories for handling precise liquid volumes. This SOP ensures consistent pipetting accuracy and reliability.

1. Objective

To establish a standard procedure for the calibration of plunger-operated pipettes (single or multi-channel) to ensure accuracy and precision in liquid handling.

2. Scope

This procedure applies to all types and volumes of plunger-operated pipettes used in [Company/Laboratory Name].

3. Responsibilities

• Analyst/User: To perform and record the pipette calibration.

• QA/Lead Analyst: To review and verify calibration records.

• Maintenance (if applicable): To assist in pipette servicing and troubleshooting.

4. Definitions

• Plunger-Operated Pipette: A hand-held device used for measuring and transferring specific volumes of liquid via a spring-loaded piston (plunger).

• Accuracy: Closeness of measured value to true value.

• Precision: Repeatability or reproducibility of the measurement.

5. Materials and Equipment

• Plunger-operated pipette (e.g., 10 µL, 100 µL, 1000 µL)

• Calibrated analytical balance (readability: 0.0001 g for ≤100 µL pipettes, 0.001 g for ≥200 µL)

• Distilled or deionized water (at 20 ± 1°C)

• Weighing boats or containers

• Temperature and humidity monitoring tools

• Calibration worksheet/logbook

6. Procedure

6.1 Preparation

1. Clean the pipette if necessary.

2. Ensure balance is calibrated and leveled.

3. Perform calibration in a controlled environment (recommended: 20–25°C and 40–60% RH).

4. Label each pipette with an ID and calibration due date.

6.2 Calibration Method (Gravimetric)

1. Set the pipette to its nominal volume (e.g., 1000 µL for a 1000 µL pipette).

2. Tare a container on the analytical balance.

3. Pre-wet the tip by aspirating and dispensing water 3–5 times.

4. Aspirate the set volume and dispense into the container.

5. Record the weight. Repeat for 10 replicates.

6. Convert weight to volume using the formula:
   Volume (µL) = Weight (mg) / Density of water (mg/µL)
   (Density at 20°C ≈ 0.9982 mg/µL)

6.3 Accuracy and Precision Calculation

• Mean Volume (µL) = Σ(volume readings) / n

• % Accuracy = [(Mean Volume – Nominal Volume) / Nominal Volume] × 100

• Standard Deviation (SD) = √[Σ(xi – x̄)² / (n–1)]

• % CV (Coefficient of Variation) = (SD / Mean Volume) × 100

7. Acceptance Criteria

(Refer to manufacturer specs or ISO 8655)

• If values are outside limits, the pipette must be serviced or recalibrated.

• Pipettes that pass shall be labeled with a calibration sticker (Date / Due Date / By Whom).

8. Frequency of Calibration

• Every 6 months (routine)

• After service or repair

• After accidental dropping or suspected damage

• Prior to critical analysis (e.g., stability testing)

9. Documentation

• Pipette Calibration Logbook

• Calibration worksheet (printout or software-generated)

• Label on pipette with calibration status

• Out-of-specification report (if applicable)

10. Abbreviations

• SOP – Standard Operating Procedure

• µL – Microliter

• mg – Milligram

• CV – Coefficient of Variation

• SD – Standard Deviation

11. References

• ISO 8655-2: Pipettes — Calibration and Operation

• Manufacturer’s user manual

• Internal Quality Guidelines.

🎓 Discover one of the best Quality Assurance courses available — click below to explore the course that’s shaping future QA skills.

https://trcjw.on-app.in/app/oc/306166/trcjw