How to Improve Accuracy and Precision With Advanced Laboratory Pipetting Techniques

Laboratory pipetting is a fundamental skill in the life sciences, and it is essential for achieving accurate and precise results.

Poor pipetting technique can lead to errors in measurement, which can have significant consequences for experimental outcomes. In this article, we will discuss the advanced laboratory pipetting techniques that can help to improve accuracy and precision in pipetting.

1. Calibration of pipettes.

The first step in improving pipetting accuracy and precision is to ensure that your pipettes are calibrated correctly. Calibration is the process of verifying the accuracy of laboratory pipettes and adjusting them if necessary.

It should be performed regularly, preferably once a year, or more frequently if the pipettes are used heavily. Calibration can be done using a gravimetric or colorimetric method.

Gravimetric calibration involves weighing the volume of liquid dispensed from the pipette, while colorimetric calibration involves using a colorimetric reagent to measure the absorbance of a known volume of liquid.

1. Correct pipetting technique.

Correct pipetting technique is crucial for achieving accurate and precise results. The following steps can help to ensure that you are pipetting correctly:

• Choose the correct pipette for the volume of liquid you wish to dispense.
• Ensure that the pipette tip is securely attached to the pipette.
• Immerse the pipette tip into the liquid to be dispensed.
• Depress the plunger to the first stop to draw the liquid into the pipette.
• Withdraw the pipette from the liquid and wipe the tip against the side of the container to remove any excess liquid.
• Depress the plunger to the second stop to dispense the liquid.
• Withdraw the pipette from the container and release the plunger to expel any remaining liquid.

1. Pre-wetting of pipette tips.

Pre-wetting of pipette tips can improve the accuracy and precision of pipetting by ensuring that the liquid adheres to the tip. It involves dispensing a small amount of liquid into the tip before aspirating the desired volume. This can be done by depressing the plunger to the first stop and then releasing it to expel the liquid.

Also, pre-wetting is particularly important when working with viscous liquids or when dispensing small volumes.

1. Air displacement.

Air displacement is a technique used to dispense small volumes of liquid accurately and precisely. Air displacement pipettes work by creating a vacuum in the pipette tip, which draws the liquid into the tip.

This technique is particularly useful for dispensing small volumes of viscous liquids or for working with volatile compounds that may evaporate during pipetting. To use air displacement pipettes, follow these steps:

• Immerse the pipette tip into the liquid to be dispensed.
• Depress the plunger to the first stop to create a vacuum in the tip.
• Wait for a few seconds to allow the liquid to flow into the tip.
• Withdraw the pipette from the liquid and wipe the tip against the side of the container to remove any excess liquid.
• Depress the plunger to the second stop to dispense the liquid.
• Withdraw the pipette from the container and release the plunger to expel any remaining liquid.

1. Reverse pipetting.

Reverse pipetting is a technique used to dispense viscous or volatile liquids accurately and precisely. This technique involves aspirating the liquid into the pipette tip beyond the desired volume and then expelling the excess liquid before dispensing the desired volume.

Further, it can help to ensure that the desired volume of liquid is dispensed accurately and can also reduce the risk of introducing air bubbles into the liquid. To use reverse pipetting, follow these steps:

• Immerse the pipette tip into the liquid to be dispensed.
• Depress the plunger to the second stop to aspirate the liquid into the tip beyond the desired volume.
• Withdraw the pipette from the liquid and tap the tip against the side of the container to remove any excess liquid.
• Depress the plunger to the first stop to expel the excess liquid.
• Immerse the pipette tip into the destination container.
• Depress the plunger to the second stop to dispense the desired volume of liquid.
• Withdraw the pipette from the container and release the plunger to expel any remaining liquid.

1. Multichannel pipetting.

Multichannel pipetting is a technique used to dispense multiple samples simultaneously. This technique can save time and increase throughput, but it requires careful attention to ensure accuracy and precision.

To use multichannel pipettes, follow these steps:

• Ensure that the pipette tips are securely attached to the pipette.
• Immerse the pipette tips into the liquid to be dispensed.
• Depress the plunger to the first stop to draw the liquid into the pipette.
• Withdraw the pipette from the liquid and wipe the tips against the side of the container to remove any excess liquid.
• Immerse the pipette tips into the destination containerDepress the plunger to the second stop to dispense the liquid simultaneously into all the channels.
• Withdraw the pipette from the container and release the plunger to expel any remaining liquid.

1. Use of electronic pipettes.

Electronic laboratory pipettes are a modern alternative to manual pipettes, and they offer several advantages over traditional pipettes.

Electronic pipettes are more accurate and precise than manual pipettes, and they can also reduce the risk of repetitive strain injuries. Electronic pipettes are available in single-channel and multichannel versions, and they can be programmed to dispense specific volumes of liquid automatically. Electronic pipettes are particularly useful when working with high-throughput samples or when dispensing small volumes of liquid.

In conclusion, laboratory pipetting is a fundamental skill in the life sciences, and it is essential for achieving accurate and precise results.