Why is the Liquid Contact Angle important?

Answer

This is the angle the liquid makes to the labware surface and relates to many factors, including adhesion and cohesion.

Figure 1

Figure 1: The contact angle of a droplet relies on the relationship between the liquid and the surface. It's how much the droplet spreads out or avoids the surface. Water and alcohol spread out a lot onto a table, they have a low contact angle. Mercury maintains it's shape and has a high contact angle.

Fluids with a low contact angle (e.g. water or alcohol) spread out thinly across a surface, meaning there is greater adhesion. This makes it hard to pipette in low volumes. Combat this by using a reverse pipetting technique. 

A high contact angle can make both aspiration and dispensing difficult as the liquid may deform around the tip. Using a deeper aspirate/dispense depth or greater 'Liquid Level Detection Extra Travel' will help to ensure the pipette tip breaks through the surface.

If you require more information please contact [e-mail] for assistance.