How to Use Pipettes and Their Functioning?

Introduction

When talking about scientific research and laboratory work, know that accuracy and precision are the key factors on which the absolute workflow depends upon. In laboratory terms, a pipette is a fundamental laboratory instrument that plays a crucial role in ensuring the qualities of accuracy, precision and reliability. 

From transferring tiny volumes of liquid to ensuring consistent measurements across experiments, pipettes are counted as the indispensable tools. Here, we’ll be discussing how to use pipettes effectively and delve into their functioning, covering different types of pipettes, proper techniques, and maintenance tips. 

Types of Pipettes

Before getting on with the usage and functioning of pipettes, it’s important to know its types that are available for use. Here are some of the commonly used pipettes for lab & research work.   

1. Glass Pipettes:

• Volumetric Pipettes: These are designed for measuring a single, fixed volume of liquid with high accuracy.
• Graduated Pipettes: These have graduation marks along their length, allowing for the measurement of varying volumes.

2. Micropipettes:

• Single-Channel Pipettes: Used for transferring small volumes (microliters) of liquid, commonly used in molecular biology.
• Multi-Channel Pipettes: Feature multiple tips for transferring liquids into multi-well plates, ideal for high-throughput assays.

3. Electronic Pipettes:

The electronic pipettes are functioning upon various dispensing protocols. More so, they offer high precision and reduced manual effort in laboratory workflow. 

How to Use Pipettes?

Using a pipette correctly is of high importance for obtaining accurate and reliable results. To do that, you must follow a proper guide that’s provided by the manufacturer of the product. 

Here’s a step-by-step guide on how to use different types of pipettes:

Using Glass Pipettes: 

1. Preparation:

• Choose the appropriate pipette for the volume you need to measure.
• Ensure the pipette is clean and dry before use.

2. Filling the Pipette:

• Attach a pipette bulb or a pipette filler to the top of the pipette.
• Submerge the tip of the pipette into the liquid sample.
• Gently squeeze the bulb to create suction and draw the liquid up to the desired mark.

3. Dispensing the Liquid:

• Move the pipette to the receiving container.
• Slowly release the liquid by either releasing the pressure on the bulb or using the pipette filler mechanism.

Using Micropipettes: 

1. Setting the Volume:

• Turn the volume adjustment dial to set the desired volume. Make sure to check the digital or analog display for accuracy.

2. Attaching a Tip:

• Attach a disposable tip to the pipette by firmly pressing the pipette shaft into the tip box.

3. Aspiration:

• Press the plunger to the first stop (first resistance point).
• Immerse the tip into the liquid sample, just below the surface.
• Slowly release the plunger to draw the liquid into the tip.

4. Dispensing:

• Move the pipette to the receiving container.
• Press the plunger to the first stop to dispense the liquid.
• Press to the second stop (second resistance point) to expel any remaining liquid in the tip.

5. Ejecting the Tip:

Press the tip ejector button to dispose of the used tip into a waste container.

Using Electronic Pipettes

1. Programming the Volume:

•  Use the control panel to set the desired volume and any specific dispensing protocols.

2. Attaching a Tip:

•  Attach a disposable tip as with manual micropipettes.

3. Aspiration and Dispensing:

• Follow the prompts on the electronic display to aspirate and dispense liquids accurately.
• The electronic pipette will control the speed and precision, reducing manual effort.

4. Tip Ejection:

•  Use the eject button to dispose of the tip.

Functioning of Pipettes

The functioning of pipettes, whether manual or electronic, is based on basic principles of physics and fluid dynamics. Here’s a closer look at how they work:

1. Suction Mechanism:

• Manual pipettes use a suction mechanism created by pressing and releasing a bulb or plunger. This suction draws the liquid into the pipette or tip.
• Electronic pipettes use a motorized mechanism to create suction, providing more precise control over the volume aspirated and dispensed.

2. Volume Measurement:

• Volumetric pipettes are calibrated for a single volume, ensuring high accuracy for that specific measurement.
• Graduated pipettes and micropipettes allow for variable volume measurements, with calibrations indicating the amount of liquid being measured.

3. Dispensing Mechanism:

• Manual pipettes rely on the user’s control to release the liquid, requiring careful technique to avoid errors.
• Electronic pipettes automate the dispensing process, minimizing human error and ensuring consistent delivery of the liquid.

Tips for Accurate Pipetting

To achieve accurate and precise results, follow these best practices:

1. Pre-Wet the Tip: Aspirate and dispense the liquid multiple times before taking the final measurement to condition the tip and reduce errors caused by surface tension.
2. Hold the Pipette Vertically: When aspirating, hold the pipette vertically and immerse the tip just below the surface of the liquid.
3. Smooth Operation: Press and release the plunger smoothly and consistently to avoid introducing air bubbles or inconsistencies.
4. Temperature Considerations: Ensure that the pipette, tips, and liquids are at the same temperature to prevent volume variations due to thermal expansion or contraction.
5. Regular Calibration: Regularly calibrate pipettes to maintain their accuracy and reliability. This is especially important for micropipettes used in critical applications.

Maintenance of Pipettes

Proper maintenance is essential for the longevity and accuracy of pipettes:

1. Cleaning: Regularly clean the pipette according to the manufacturer’s instructions. Disassemble the parts if necessary and use appropriate cleaning agents.
2. Calibration: Schedule regular calibration checks, especially for micropipettes. Use calibration services or perform in-house calibration using standard weights.
3. Storage: Store pipettes vertically in a stand to prevent damage to the tips and internal mechanisms. Avoid exposing them to extreme temperatures or direct sunlight.
4. Replacement of Parts: Replace worn-out parts such as O-rings, seals, and tips to maintain the performance and accuracy of the pipette.

Conclusion

Pipettes are one among the significant tools in the scientific community that enable precise and accurate results as a liquid handling instrument. Similarly, it’s important to understand how to use different types of pipettes and their functioning for achieving reliable experimental results. Furthermore, you can follow proper techniques for maintaining the equipment. Additionally, by adhering to the best practices, researchers & lab technicians can ensure the effectiveness of their pipetting activities; further contributing to the advancement of scientific knowledge and technological innovation.