Imagine pipetting your publication experiment and then your favourite lab mate has an urgent question, which of course you helpfully answer. But when you finally turn back to your experiment you suddenly are not sure which pipetting step you were at. It’s happened to us all!
Efficiently keeping track of your samples in a sometimes loud and distracting environment (such as a lab) is a skill I wish I had learned earlier in my lab life. One way I found useful to keep my focus and reduce mistakes is to use patterns; it can help you organize your bench, Eppendorfs, labels and even the tips inside the pipet box.
If you are a well-organized person with a concentration of steel, following these tips might feel redundant to you. But if you are easily distracted (like myself) or just want to improve your workflow and spend less time and concentration on labelling and reading labels, some of them might come in handy.
1. The Pipetting Scheme.
- Tick off everything. The most basic tip to keep on top in your pipetting scheme is to tick off everything you have already added to your reaction. This might seem obvious, but is nevertheless something we always have to stress to undergraduate students joining the lab. It provides a nice safeguard when interrupted and gives you the reassurance that you have added everything into the mix in case your experiment fails.
- Order your reagents. Some pipetting schemes conveniently come in pipetting order, already reducing the chance of mis-pipetting. However, if this is not the case, I find it helpful to place my reagents on my bench/in my icebox in the order I want to pipet them, and put them aside once used. That way, you don’t pipet anything twice and you also don’t forget anything you overlooked in your scheme.
- Pipetting multi-well plates. This one was a real eye-opener when I watched my lab mate do it for the first time. Keeping track of where you are in multi-well plates is fairly easy if you realize that your pipet box has the same format as your 96-well plate. If you use the tip/row of tips corresponding to your well/s, no distraction can throw you off your experiment. (The only thing better is to find a robot that does your pipetting for you.) To further mark your current well position you can use the plate lid to cover the parts you’ve already pipetted or, analogously, move the plate along a piece of paper below it.
2. Labeling Your Samples.
- Naming. Our samples usually have complicated names, with descriptions and distinguishers. But life is just too short to label Eppendorfs in detail – especially when faced with a multitude of samples so similar that you would need three caps to put all the necessary information. For these kinds of experiments it is quite useful to abbreviate your sample with numbers, letters or symbols (just don’t lose that reference sheet!). I find it helpful to distinguish Eppendorfs of numerous, parallel time traces by using Latin (1, 2, 3) or Roman numbers (I, II, III), the alphabet (A, B, C) or symbols (circle, triangle, rectangle).
Generally, it is always advantageous to use patterns already existing, such as numerical and alphabetical order. You could, for example, always pipet your PCR primer with the lower number first (providing you give them a number), or when you express several proteins in parallel always handle them in the order of the alphabet.
- Color-coding. This was the one of the most practical “tricks of the trade” I learned from my Master’s thesis supervisor. The brain is much faster at recognizing colors than it is in reading words or multiple-digit numbers. Reading words on the labels and fitting them to the corresponding writing on another item takes concentration you’d most probably rather invest in more interesting tasks. Color-coding is applicable to almost anything. You can use it to distinguish your protein preparations (protein one always in red, protein two always blue), your buffers and reagents, time traces, experiments, the structure of your lab book and so on.
One note of caution though: don’t overdo it with colors. They are extremely useful if they stand out, but can cause even more chaos if you use too many.
In my experience, using patterns gives you reassurance and saves time, and the more you use them, the more secure you will feel and the less mistakes you will make in your experiments. I’m sure many of you have developed your own strategies I would be curious to hear about. Comment below with any suggestions you have to help us keep track of our pipetting!