Pipettes are essential tools in laboratories for accurately measuring and transferring liquids. Proper pipetting techniques and best practices are crucial to ensure accurate and reliable results, prevent contamination, and maintain the integrity of samples. Here are some common pipette techniques and best practices to follow:
1. Pipetting Techniques:
Calibration and Zeroing:
- Before use, ensure that the pipette is calibrated and zeroed correctly according to the manufacturer’s instructions.
Choosing the Right Pipette:
- Select a pipette with the appropriate volume range for the desired measurement. Using a pipette that is too small or too large for the volume can lead to inaccuracies.
Preparing the Pipette:
- Attach the correct tip size to the pipette, ensuring a secure fit. Make sure the tip is free of contaminants or moisture.
Pipetting Up and Down:
- Pipette up and down several times to mix the sample thoroughly before aspiration, especially for viscous or concentrated solutions.
- Immerse the tip into the liquid to the desired depth, then gently press the plunger to the first stop to draw the liquid into the tip.
- Position the tip at the destination container’s surface, and depress the plunger slowly and steadily to release the liquid. Avoid rapid or forceful dispensing to prevent splashing.
- For accurate and complete dispensing, some pipettes have a second stop on the plunger. Use this feature to expel any remaining liquid from the tip.
Touching the Liquid Surface:
- Do not allow the tip to touch the liquid’s surface during aspiration or dispensing, as this can lead to contamination or inaccurate volumes.
- Use filtered pipette tips or barrier tips for handling potentially infectious or hazardous materials to prevent contamination of the pipette.
2. General Best Practices:
Maintaining Pipette Hygiene:
- Regularly clean and disinfect pipettes, particularly the exterior surfaces and plunger, to prevent cross-contamination.
Using Disposable Tips:
- Always use disposable tips and change them between samples to prevent cross-contamination.
- Use a fresh pipette for each solution, especially when working with sensitive samples, to prevent cross-contamination.
Avoid Vapors and Aerosols:
- When pipetting volatile or hazardous substances, work in a well-ventilated area or use a fume hood to prevent exposure to vapors or aerosols.
- Store pipettes upright in designated stands or racks to prevent damage to the tips and maintain accuracy.
Routine Calibration and Maintenance:
- Regularly calibrate pipettes according to the manufacturer’s guidelines and perform routine maintenance to ensure accurate measurements.
- Train users on proper pipetting techniques and safety practices to maintain consistency and accuracy across the lab.
Adhering to proper pipetting techniques and best practices is essential for producing reliable and consistent results in laboratory work. It ensures accurate measurements, prevents contamination, and contributes to the overall quality of scientific research and experimentation.