Hi there,
in our lab we are having some nasty issues with bubbles ejected during the dispense procedure. The issue seems random or, at least, we did not find any pattern in this behaviour.
We nornally use the standard 300uL black filtered tips, but the non-transparency of the tip does not allow to investigate at which point of the process the air enters the tip (during aspiration? during transport? during dispense? etc…).
To investigate the source of issue, we were thinking about using the 300uL clear tips so that we hope to “see” the source of issue and solve it, maybe by modifying some parameters in the LiquidClass, and then get back to the standard black ones for “real” experiments.
However, clear tips are available only unfiltered.
My question is:
are the clear unfiltered tips identical to the black filtered ones as far as geometry is concerned?
what can happen if I set a LiquidClass by using the unfiltered tips and, then, I switch back to the filtered ones? Do I have to expect minor consequences (e.g. slightly worse precision/accuracy) or I risk to nullify any advantage introduces by the optimized LiquidClass?
Tips are probably a smaller contributing factor than the type of liquid and/or liquid class in use. Is this a soapy or viscous solution? Things like dispense speed, blowout, etc are all going to have much bigger impact than the tip type.
For a quick test you can likely just pick up a benchtop pipette and try to figure out some cases that lead to bubble formation.
Lots of great resources on this site to help with LC creation, and feel free to add some info about your specific liquid type and folks will definitely chime in with suggestions
As far as clear vs black tips, you use them interchangeably. For filter vs unfiltered tips, I am sure it is the same since I did look into the liquid class for both, and they are identical. I also use them interchangeably in my protocols, as long as cLLD is not used, which then requires the black tips.
As for optimizing the liquid class, as @evwolfson stated, you can reference the Hamilton liquid handling ebook for guidance on how to optimize your pipetting technique based on the type of liquid you are working with.
Just to clarify that Hamilton does offer clear, filtered tips. To answer your questions -
Yes, they are the same geometry
For development purposes, I would recommend just using the same tip rack definition and liquid class you’re currently using, but physically use clear tips. The LC parameters would be very similar if not identical, clear vs. conductive.
In general, I recommend having some clear tips handy for such work! Feel free to DM me if you just need some samples sent out.