Don’t get stuck in a sticky situation trying to suck up sticky solutions! Pipetting viscous (syrupy) liquids can be annoying - and annoyingly inaccurate if you aren’t changing your strategy! blog form: bit.ly/pipetting_problems
Here are some tips - including: don’t cut the pipet tip! (unless you’re just transferring liquids and don’t care about accuracy). What you can do…
Try reverse pipetting, where you depress to the second stop when aspirating (sucking up liquid), then the first stop when dispensing (pushing the liquid out), leaving the leftovers in the tip (as opposed to the “normal” forward pipetting we typically do where you go down to first stop when aspirating (so you suck up just what you need) and the second stop when dispensing, pushing it all out.
Pipet really slowly - give the liquid time to make its way in and out
Pipet at a slight angle onto the wall of the container - let adhesion give you a hand
Don’t immerse your tip farther than you need to - liquid can stick on the outside of the tip, leading you to transfer more than you wanted
Consider making stock solutions of viscous liquids (like 80 or 50% glycerol) which are easier to work with - you can make these by pouring into a graduated cylinder of water-volume you want - pour to line, parafilm the top, and invert for a much flowy-er fluid.
If you’re really worried about pipetting viscous solutions, you can try a positive displacement pipet, where there’s a solid thing pushing the liquid down and out of the pipet rather than just air, like most of our pipets use.
And although you shouldn't cut your tips, they do make special wide bore tips you can use.
For a comprehensive guide to this sort of thing, I found this great resource: Sartorius Techniques for Pipetting Challenging Liquids, Sandra Söderholm and Paulus Artimo, 2021 www.sartorius.com/resource/bl...
And here’s a cool teaching guide on making training tips with marker lines: Douglas A. Bernstein; Training Tips: Tools to Teach Pipetting in the Classroom and Lab. The American Biology Teacher 1 September 2018; 80 (7): 536-539. doi: doi.org/10.1525/abt.2018.80.7...
                   
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