Friday, 18 October 2013

Good pipetting rules of thumb


Accurate micro-pipetting is probably the single most important physical skill that a molecular or cell biologist need learn. It is the foundation upon which the vast majority of our experiments are built.

Pipettes are to us as brushes are to painters. They are the tools by which we achieve our aims; any mistake in pipetting at any stage stands to affect the outcome of our experiment.

Understandably, there are many resources available to help inform best pipetting practice, which I recommend budding biologists make use of. This is a nice one, and there are plenty of (cheesy) videos around too. People should also know a bit (if not a lot!) about how they work, how they can go wrong, and the different ways in which they can be used – there’s an unwieldy if thorough guide covering these here.

However, all this advice tends to focus on what’s best for the experiment – which is important – but overlooks another concern; your body.

Experiments can often involve highly repetitive movements, for extended periods of time. This isn’t that great on your mechanisms, particularly those of your thumb and wrist (as well I know!), and can cause repetitive strain injuries. There are a number of ways you can cut down on these risks, but here’s a quick rundown of the ones I think are worth bearing in mind:

         Don’t rush. Be fast, by all means – if you’re able – but hurrying usually means you do things the wrong way (both in terms of your data’s and your own safety)

         Set up your bench. My bench might look a mess when I’m working, but it’s organised so that I can access everything I need to without stretching or moving lots of stuff around. Which leads onto…

         Minimise. The injuries you’re at risk of are cumulative in nature, so you want to get away with using the minimum force and number of repetitions you can get away with. Maximise use of master mixes, reverse-pipette when needed, use multi-channel/step pipettes where possible, and for the love of all that is good, don’t bang your pipette tips on as hard as you can! (This is a bit of a bugbear of mine; the more you push it on just adds to the force required to get it off! It’s also damaging to the pipette in the long run. Gentle but firm pressure with a slight twist should be more than enough to form a strong enough seal for aspiration)

         Mix it up. If you’re able, swap hands every now and then to split the load. Admittedly, most people’s weaker-hand is probably less reliable than their stronger-hand, but accuracy’s sometimes less important – for instance, a lot of your larger-volume wash steps can probably afford to take the hit

         Take breaks. The most effective, but least practical option (which I am guilty of ignoring most of the time!). Try to break up your experiments, either with pauses or activities that don’t put so much pressure on your wrists and hands (so you can still be working, fear not PIs!).

The best part is that most of these tips help improve both the accuracy and speed of your work too.

Remember, you only get one pair of hands (if you’re lucky), so don’t put them at risk for your work, no matter how important you think it is at the time. Speaking from experience, it can also impact directly on your research, as my current bout of tendonitis tenosynovitis (damn you qPCR!) put me out of commission lab-wise for a fortnight*. It’s in everyone’s best interest for you to take the time and effort to pipette safely, and that includes your data.

OK now I’m anthropomorphising results. Time to end blog post.

* I know it seems rich me writing this article after admitting I have the injuries I claim knowledge of preventing, but it's a bit of a 'do as I do and not as I say' situation. I happen to have always had dodgy wrists, no doubt from a childhood spent on computer games, an adolescence spent typing, and an adulthood spent pipetting. I think the addition of thumb-swipey smart phone ownership was the last straw.

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