3 types of pipetting contamination

1. Pipette-to-sample contamination:  The pipette or pipette tip contaminates the sample.

How to avoid it:

Use sterilized filter tips, for example, SafetySpace tips from Sartorius, to keep the pipette body free from contaminants.

Change the pipette tip after each sample.

Autoclave or disinfect the pipette with ethanol regularly. Choose pipettes that are autoclave compatible. For example, Tacta from Sartorius.

2. Sample-to-pipette contamination: Pipetted samples enter the pipette body, contaminating it.

How to avoid it:

Use filter tips or positive displacement tips to prevent samples from entering the pipette body.

While pipetting, hold the pipette in a vertical position. Store pipette in an upright position.

Tilt the bottle while pipetting.

Avoid splashes of samples from entering the pipette by slowly releasing the button. Choose pipettes equipped with soft ejection feature. For example, Picus or Tacta from Sartorius.

3. Sample-to-sample contamination: Residue pipetted samples are carried over to the next sample. Typically occurs when the same tips are used multiple times.

How to avoid it:

Change the pipette tip after each sample.

Use filter tips or positive displacement tips to prevent samples from entering the pipette body, and into the next sample.

Ensure pipette tips make a leak-tight seal on the pipette to avoid sample leaks. For example, Optifit Tips by Sartorius.