Analysis of tip-usage methods

Warning: the following may not be comprehensible for those not working in a lab.

So the other day, baymate and I were discussing how we use up our pipette tips. Not in terms of experimental procedures or in the types of orifices we jam them in, but in the order we remove our pipette tips from the pipette tip-box.

I tend to start off in one corner and work my way diagonally through to the other end:


i-82c8376af2fed6b085d89f982e480b17-tips2.jpgIn contrast my baymate likes to cut right through the middle of the box to form a horse-shoe pattern. (Quite a bold strategy)

In order to investigate this further we went around the lab and asked people how they used up their pipettes. The results of this informal survey are bellow the fold.

We first visited a postdoc in the neighboring bay. Her strategy, when using sterile tips, is to start from the periphery and work inwards, in this way she used those tips that are most likely to become contaminated first and those tips that are more resistant to contamination last. An example is shown below.


i-c2e2c02d4d8263d32a561f9843b60fa2-tips4.jpgWhen employing non-sterile tips, her tip-using habits were very bizarre - a combination of the diagonal method combined with single tip extractions from the tip bulk. (An example is shown on the right.)

After this initial success we decided to examine all the tip-boxes in the room. We soon discovered that the most widely spread tip-utilization practice was the linear ordered tip usage method. Yes, most researchers around here utilized tips by picking them out in order along a single row. When a row was finnished they would move on to the next row. We dubbed this practice, the anal-retentive tip usage method (ARTUM). Here are two examples:


To the right is a clasic ARTUM box.
Below is a diagonal version of the ARTUM technique. i-14f8c670aae170495ab53a2c19e15216-tips5.jpg

When we quizzed a practitioner of ARTUM, he informed us that he would secretly steal tips from his ex-baymate who was a devoted disciple of this method. In order not to be caught, the postdoc we questioned informed us that he would take his baymate's tips in order. Soon our tip felon found that he was practicing ARTUM on his own tips. Obviously the ARTUM technique is very contagious and potentially addictive. You have now been warned.

Interspersed between the ARTUM boxes were the remains of very chaotic and seemingly random tip usage strategies. In the following example a strip of tips was cleared from the center.i-0a1764760d1ce0fc83258c38249b0e52-tips7.jpg

Does this tip usage pattern indicate something? We though that the tip-free region resembled a fish. Was this researcher gone on a two-hybrid fishing expedition? Or perhaps they're suppressing some deep scar inflicted by their christian upbringing. We'll never know.

There were other boxes with very interesting patterns. Here's one that was seen in the tissue culture room.i-cd1f7498787252ccdcc46a4018c6b10b-tips8.jpg Was this an example of a reverse sterile tip utilization method? We are currently setting up a camouflaged camera in order to get to the bottom of this interesting tip-usage phenotype. Stay tuned ...

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Actually, the method you so derisively name ARTUM is superior on those occasions when it is possible to utilise an 8-tipped pipette, for example when preparing an 8 x 12 container of PCR samples for sequencing.

Where will your fancy patterns leave you then, eh?

By Ian B Gibson (not verified) on 20 Jul 2007 #permalink

Hilarious! We used to talk about this in our lab as well. I was an ARTUM. Only one person in the lab used tips completely randomly, and he was probably the smartest one of us.

LOL! This is so awesome. It could only have been better if the photos were labeled as Fig.1, Fig.2, etc. :)

Sadly, I am an ARTUM practitioner. As Ian pointed out, this makes it easier to go back and forth with my single- and multi-channel pipetters. When I was in grad school, my labmates and I used to do interesting patterns like making faces in the field of tips, or using every other tip at a time (making a cool dotted pattern).

He he! I am an ARTUM definitely. In my last lab we also talked about this and we decided to do artwork with the remaining tips - you know, a smiley face, a gun. Tried to do a naked woman but couldn't get it to look right!

It's interesting that you consider the ARTUM method anal-retentive, but not any of the other obsessive compulsive activities you describe.

I started using the "start from the outside and move in" method after I'd tired of loosing them to the autoclave tape used to reseal the boxes, which seems to have some sort of magnetic attraction for clean/sterile equipment.

With the non-sterile ones I attempted to write childishly tame rude words.

To be honest, it has been so long since I have used many pipette tips, that I can't remember what method I used. I do remember a guy in grad school who would go row-by-row, but only use every-other tip, to create a checkerboard pattern.

Even though I don't use tips myself anymore, if I see a tip box with the lid off when I walk through the lab, I do compulsively put the lid back on.

By PhysioProf (not verified) on 21 Jul 2007 #permalink

A post-doc I worked with thought there was a correlation between the way people eat corn on the cob and the way they select tips.

I'm surprised no one uses a symmetric method. Sometimes, I'll take tips in random locations on either side of a line of symmetry, making interesting patterns. Other times, I'll spiral towards the middle. So much fun to be had.

I use a variety of methods according to my mood and how complex the experiment is. So for doing things where I don't have to think much (or count tubes) I'll do a 'diagonal bounce' effect - start in one corner, move along the diagonal until hitting an edge, then mirror bounce. This makes for fun when crossing your tracks of course, but by the time you have used 48 tips you have ended up in a corner again and left a nice alternating pattern.

ARTUM is good if I'm doing lots of repetitive stuff and I need to keep count. I also spiral in, and spiral out from the centre. And when I'm using a communal set, say in the gel room, I take them randomly to piss off the ARTUMers.

I am absolutely a classic ARTUM pipetter. However, since I have the tidiest bench in the lab, others often use my bench for their bacteria work, and they tend to randomly pick out pipettes. It aggravates me beyond description -- so I guess anal retentive is a pretty accurate title.

Has anyone ever seen a Jesus face in the tips or the tip holder-holes left in the tip box?

Also, is there any correlation between personality type and the pattern left in tip boxes? Just wondering.


That correlation between corn and tips may extend to taking out eggs from a carton. My baymate (who takes tips from the center first) also takes her eggs from the center of the carton and works her way outwards. She claims that this technique prevents "unbalance" and also reduces the number of tips/eggs that may fall out as she removes tips/eggs from the edge of the box (an often precarious procedure).

Okay, here's my quirk: When the tip box has got only one tip left and I don't need to use that tip, I throw it away, just so that my tip box will not look "snaggle-toothed".

Sometimes I will even do this to the last tip in the row, but not always.

How many tips do you use up in one day?

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