Demystifying Pipet Tips

 

Background

I earned my B.S. in Medical Technology from Indiana University in 1971.  This was just a decade after its introduction into the market. 

The first micropipette was patented in 1957 by Dr Heinrich Schnitger (Marburg, Germany). The founder of the company Eppendorf, Dr. Heinrich Netheler, inherited the rights and started the commercial production of micropipettes in 1961.

The adjustable micropipette is a Wisconsin invention developed through interactions among several people, primarily inventor Warren Gilson and Henry Lardy, a professor of biochemistry at the University of Wisconsin–Madison.

I began my career in lab distribution sales with Scientific Products in the fall of 1971 so I literally “grew up” with pipettors.  Having used some of the most unsanitary and inaccurate glass pipette in my training (yes, we sucked dichloromethane into our mouths routinely) I was fascinated by the idea of a better way to move liquid from one place to another.

I retired from VWR International in 2013 and started LPS.  Five years prior to my retirement, I approached VWR with the idea of having a web based pipet tips selector.  “I have pipettor X, tell me what tips will fit.”  I presented this to the company who literally laughed at the idea and sent me home.

I was convinced that this was a tool that was really needed and so I began, in my spare time, to do the research required to construct what became Pipettipfinder.com.  It took me five years and I collected samples of every pipet tip I could find.  I carefully measured and recorded everything.  I visited many of the manufacturers.  Working with programmers, I prepared a huge database and on roughly the same day I was ready to launch, VWR announced that they had developed a “Pipet selection tool.”  It only “found” the brands VWR sold, of course, but after being told my idea was foolish, I was never credited by anyone at VWR with the idea.  

 

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The Beginnings of a Classification System

 

What makes a tip “proprietary”?

 

Pipettor manufacturers have struggled mightily since the 1970’s to find a way to make a pipet tip that will ONLY fit on the pipettor they make.  If you can prevent anyone else from making a tip that will work on your pipettor, you create a de facto monopoly.  How do you go about this?

 

It’s got to be a “better mousetrap.”

• - It reduces repetitive stress, is easier to eject, and takes less force to load.  (E.g., Rainin Light Touch)

• - It loads more easily and doesn’t tend to fall off.  (E.g., Thermo Clip-Tip.)

• - It accommodates multi-channel specialty pipettors (E.g., Thermo Matrix)

• - It has a unique tip ejector which requires a special hub to work properly.

 

And, it goes without saying, but all of these “better” ideas are patented to keep competitors out.

 

These are just some of the selling points that convince some people to overlook the major downside of buying a pipettor that uses a proprietary tip:  If there is ever a supply chain problem (e.g., the Covid-19 pandemic) you have no second source of supply.  You either stop pipetting or buy a universal fit pipette to tide you over until the proprietary tip maker starts production again.

 

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What makes a tip “universal”?

This is my definition and I’m sure there are other definitions:  Here is a condensed list:

 

• - It fits on a cone shaped pipettor hub.

• - It fits on many different types of pipettors.

• - For non-macro pipettors, it comes in three standard sizes, small (micro), medium and large.  Small = 10 or in some cases 20uL or less), Medium - >20 to 499 uL and Large = 500ml to 2ml.

 

What are Macro tips (5 & 10ml) advertised as “universal” fit?

There are four different major “styles” of macro tips (and there may be more!):

 

(J) Finnpipette Style - 147mm (L) by 8mm (Hub diameter)  Thermo Finn & Brand pipettors

(I) Eppendorf Style - 120mm X 12mm  Eppendorf & Socorex pipettors

(K) Gilson Style - 123mm X 12.5mm  Gilson, Rainin (non-LTS) 

(H) Universal Style - 145mm X 13mm  Nichiryo, Scilogex, VWR Private Label

 

There is one proprietary macro tip, the (L) LTS Style which, of course, only fits the Rainin LTS pipettor.

 

As you will notice, each grouping has been given a letter designation which I will describe next.

 

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Pipet Tip Attributes

 

In order to classify pipet tips, I have developed a coding system to help locate the exact tip you are searching for.  Here is a list of the classifications:

 

 

The following is a list of the codes assigned to various robotic tips:

 

 

How do I search for tips on LabProServices.com website?

 

• Example 1:  A 200 uL yellow universal fit tip, in racks, sterile.  Search for 200-R-S-YL.

• Example 2:  A 1250uL non-sterile bulk tip.  Search for 1250-B.

• Example 3:  An LTS style 300uL low retention filter tip in racks, sterile.  Search for 300-LTS-R-F-S-L

• Example 4:  A 5ml tip in bulk, for a Finnpipette.  Search for 5000-I-B.

 

All of the pipet tips on LPS’ website have these codes embedded in the description making it easy for you to find just the tip you are looking for!  If you do not get a result, make sure you have the search in the correct order and try again.  We may not have that particular tip in our offering.  Many of the robotic tips listed above we do not offer for sale.

 

Just one note, I have not differentiated different rack types.  There are single racks, stack racks, side-by-side racks and more that this system doesn’t classify.  Make sure you look at the rack type you prefer.

 

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Summary

Wouldn’t it be nice if every tip maker adopted this coding method?  That would really take the guesswork out of finding the right tip.  Hopefully by publishing this someone may see the value.

 

I never miss the opportunity to give this advice:  DON’T BUY A PROPRIETARY PIPETTOR.  A follow up on this, if you HAVE bought them and you are struggling to find tips, BUY A UNIVERSAL PIPETTOR TO PLUG THE GAP RATHER THAN PAY A FORTUNE FOR SCARCE BRANDED TIPS!  A new pipettor is far less than the cost of a case of tips.  Can you think of a better time to try something new and different?

 

If you are in search of a pipette to reduce repetitive stress, there are many great options available today that weren’t years ago when the LTS pipette was introduced.  The quality, accuracy, and reproducibility of pipettors today is nearly identical in most popular brands.  Making a poor quality pipettor is the kiss of death - word spreads quickly.

 

Finally, don’t be afraid to try something you haven’t used.  There are lots of great options out there and while a familiar “feel” is comforting, looking over the horizon is always a good idea.  Most manufacturers offer demo models for you to try before you invest.