Have Pipettor Manufacturers Buried Your Head in the Sand?

Have Pipettor Manufacturers Buried Your Head in the Sand?

Is this the position you have been put in by your pipettor manufacturer?

Have they convinced you that if you do not use their brand of tips – no matter what the cost – that you will be (insert gasp here…) introducing error into your experiments that may jeopardize your results? Why take the risk? Just accept this "truth" and bury your head in the sand. It makes your wallet much more accessible to them!

As I scientist, you should be asking questions:

  1. Can you measure the decrease in error in a real-life test?
  2. What are the other sources of error that will have a greater impact on my results? And, most importantly,
  3. What is the risk-reward ratio?

The argument for buying tips from the

company who made your pipettor.

#1 - We made the pipettor, and to ensure you get the error rates we advertise, you must buy the tips we used to perform the tests.

Since pipettors were first introduced in the late 1960’s, companies making pipettors have done whatever possible to convince buyers that only they know the REAL secret of making quality pipet tips because they designed and built the pipettor. Who else could possibly do it better?

#2 Why would you risk the results you are going to publish by going out and buying cheap pipet tips and take a chance on introducing error?

If you are pipetting samples that are worth thousands of dollars per milliliter, can’t you afford to spend ten to thirty cents on a pipet tip? (If you are saying, I’ve heard this all before, you’ve got the point.)

#3 We run a quality lab. We only buy name-brand, quality products.

This is the classic IBM argument: Nobody ever got fired for buying IBM.

#4 We bought a pipettor with a proprietary tip. So we really don’t have an option. We have to buy the manufacturer’s tips.

The decision to buy a pipettor, with a life span of many years, that you know only accepts a tip made by that manufacturer, carries its own risk set. You have accepted that you will never use any other tips than those made by the pipettor vendor, presumably because you have complete faith in this vendor. But the new risk is that this vendor at some point may have a supply problem and if so, you have no options. You are out of business. Even large companies, such as Mettler-Toledo’s Rainin division, have had serious stock-outs, recently sending panicked buyers scrambling to find product.


Pipettor makers make “razors.” They do NOT want you buying “blades” somewhere else!


It’s odd how aware people are of the razor blade / razor analogy (“The money is in the blades, not the razor!”) For years these same people have scoffed at some of the obvious attempts people have made to convince them to stick with the “brands you trust” even though the potential savings for finding an alternative are far less expensive. Here are some that come to mind:

#1 - Razor blades. Is there any reason we pay $25 for 4 blades now when just a few years ago paying this much would have been considered ludicrous.

#2 - Toner Cartridges. Only an H-P toner cartridge will truly give me the right results in my H-P printer. Why take a chance?

#3 - Reagents for my _____ instrument. Have you ever been told that if you don’t use our brand of reagents in the instrument you bought from us, your warranty will be void? If you haven’t experienced this strong-arm (and illegal) tactic yet, you are lucky. Manufacturers have been playing this gambit for years. And it works as well today as it did back in the late 1970’s when it was first popularized. I’ve often asked people who have been victimized in this manner if they would listen if their Ford dealer told them that the warranty on their new car would be void if they used anything other than Ford antifreeze? I mostly hear crickets at that point.

So why all of these shenanigans? Because they realize that the profits are in the consumables! And it is well worth the expense to do whatever necessary to keep the fear in place and get people to pay 3 – 10X what they should to get a “quality” product. And, sadly, because we scientists are so risk-averse, it works.

The arguments FOR buying tips from someone other than

the company who made your pipettor.

#1 Few pipettor manufacturers make their own tips. They buy these from companies whose core competency is making pipet tips.

If you ever visited one of the very few companies who actually manufacturer pipet tips as I have, you can’t help but notice that the tips are going into boxes with logos of a panoply of companies. Many of them are well-known pipet manufacturer brands. And this makes sense. If you are good at designing and building pipettors why would you want to invest in injection molding machines? You would, of course, sign a contract and outsource this process. And that’s exactly what companies do. They won’t tell you who they outsource it to, but it’s pretty easy to tell if you look at the tips.

#2 The errors that may be introduced because of pipet tip design rank at the very bottom of a long list of potential sources of error and pale by comparison.

Thermo Scientific, one of the world’s largest manufacturers of pipettors and tips has published a very useful guide titled “Good Laboratory Pipetting Practices (GLP).

Thermo hasn’t lost sight of the fact that profits are in the tips. However this guide is one of the first – and best – documents written by a manufacturer who treats this topic as a scientist would. On page 14, the closest they come to pusing customers to purchase their tips is: “Check that you are using tips in agreement with the manufacturer’s specifications. Thermo Scientific pipettes are calibrated using Thermo Scientific pipette tips.”


*On page 21, there is listing of factors affecting the accuracy of air displacement pipettors. These include:

  • Temperature

  • Density

  • Altitude

Taking into account all the sources of error, the biggest variable of all is pipetting technique. Are you performing EXACTLY the same procedure sample to sample, day-by-day? Person-to-person? Be honest!


A recent study (May 11, 2017) by Tatjana Bosnjak from the University of Oslo, Norway Department of Pharmaceutical Biosciences published in a Quartzy.com Blog post goes even further:

1: Choose the proper pipette: Most of you likely work with air-displacement pipettes. There is nothing wrong with that approach—they are, indeed, highly accurate and used for standard pipetting applications. A few physical factors such as altitude, temperature, and density of liquid can influence pipetting accuracy—even if your pipetting technique is perfect—and that is something you should keep in mind. The most important factor is temperature. If there is a difference between the temperature of the liquid you are pipetting and the room you are in, the volume you wish to aspirate will not be the same as the nominal pipette volume. So take your time and bring your liquids to ambient temperature. Positive-displacement pipettes are more accurate because they don’t have an air cushion inside, which can be affected by temperature and pressure. Instead, they have a unit comprised of a barrel and a tip, which are both dispensed when pipetting. As a result, they are used only in certain occasions, as this characteristic makes them more expensive. They are more suitable for work with volatile reagents and are mostly used for amplifying techniques, such as PCR.

2: Clean it up: Make sure your pipette is clean by wiping it with 70% ethanol before use.

3: Eliminate that troubling temperature factor: If your liquid is colder than the room temperature, the first aspirated volume will be larger than expected. When working with warmer samples, the volume will be smaller. Interestingly, all subsequent volumes would be accurate if using the same tip. The solution is simply to pipette up and down a couple of times, empty the pipette tip, and then aspirate your desired volume.

4: Work with the proper mode: Use the standard rather than reverse pipetting mode when pipetting aqueous solutions, and the opposite when working with viscous materials. Reverse mode implies pressing the pipette past the first stop, aspirating the sample, and then pressing the plunger until the first stop. With aqueous solutions, this technique will result in over-delivery, just as standard mode will result in under-delivery of viscous samples.

5: Pause: I always pause for a second after aspirating my sample and before taking out the pipette. This ensures that the liquid receives the needed time to move up the tip.

6: 90°/45°: Remember to aspirate at 90° and dispense at 45°. These angles have been proven in tests to increase accuracy.

7: Put it down! When you’re not pipetting, put your pipette aside. Holding it in your hand causes heat transfer, which subsequently affects your measurements.

8: Pre-wet the tip: Pre-wetting the pipette tip is an important and very commonly overlooked factor that can influence your accuracy and data integrity. Pre-wetting has multifold advantages, such as preventing cross-contamination by flushing out any residual substances or increasing the humidity within the tip, thereby reducing the amount of sample evaporation. Pipetting several samples without pre-wetting results in lower volume for the first few samples. So aspirate and eject your sample 2-3 times before aspirating for the actual delivery.

9: Test yourself: More often than not, users are confident about their pipetting technique. Nevertheless, it won’t harm you to conduct a little experiment on yourself. Take a 100 µL of distilled water and dispense it into a tared container on a balance with sufficient precision to weigh this volume. The number on the analytical balance should be 0.100 g. In the case that the mass is different than expected, you can calculate actual pipetted volume by using the following formula: volume = mass/density. As you all know, the density of dilute aqueous solutions is 1.000g/mL at standard temperature and pressure (apply correction factors if needed). Repeat the same procedure 10 times and record the masses you acquire. If the variation is more than +/- 0.5%, then you have some practicing to do!

Techniques among pipette users vary greatly depending on their background and training. It is something that is often overlooked and somewhat taken for granted. Rarely is any scientist a sole practitioner of a particular experiment, so these variations can influence overall results. By improving our technique, we improve accuracy and secure data integrity. And remember, even the most experienced users can make improvements!

#3 It makes a huge difference to your budget!

Let’s use an example of a lab who buys Eppendorf brand filter tips:


The price per tip ($173 / 960 ) = $0.18 per tip. The comparable tip, found on PipetTipFinder.com is made by Labcon and it costs about $0.07 per tip when purchased by the case of 11,520.

So let’s see what the difference would be given different annual usages of tips:

Annual Usage

$ 0.18

$ 0.05



$ 1,800.00

$ 500.00

$ 1,300.00


$ 9,000.00

$ 2,500.00

$ 6,500.00


$ 18,000.00

$ 5,000.00

$ 13,000.00

Now you can see why the pipettor manufacturers spend so much to make sure you continue to be afraid to purchase your tips anywhere else?

Exactly what is it about a “bad” pipet tip that makes it “bad?”

The most important thing is that the tip fits on the barrel of the pipettor with no air leaks. So let’s assume that this is what’s happening because if it isn’t you would be able to draw a sample up. You won’t miss that.

If it’s got particulates or liquids in it that you can see, that’s not going to be good. If it has chemicals or contaminants in or on it, especially those that may interfere in your experiment, that’s not going to be good. But neither of these is going to have an impact on your reproducibility. These are show stoppers.

So assuming you are looking at a clean tip that has no air gap, the only remaining variable is the interaction of the sample with the tip – especially the inner surface of the tip. And the variability you are trying to eliminate is having a tip that retains some of your sample once it is dispensed. And even retention might not be an issue if the volume were uniform from tip-to-tip. You may suffer some inaccuracy, but it won’t impact your precision! And you can compensate for precision if your pipettor is adjustable. A simple dye test will tell if there is fluid retention in the tip.

Everything I have described in this last paragraph is something the end user should be considering. In other words, checking for fit, contamination, retention, accuracy and precision is your responsibility! You should always select the right tip for the sample. If you need a low retention tip (myth buster: low retention is not always preferred) then it’s your job to have these on hand.

So what should you look out for when choosing a tip from someone other than your pipettor manufacturer?

#1 Choose a manufacturer with a proven track record of quality.

There are only a few U.S. companies who actually make tips. And even fewer still who take all of the steps necessary to ensure that you are getting a fully qualified product from lot-to-lot, month-to-month and year-to-year. This assurance means that they must:

A: Test every lot of tips and havea Certificate of Analysis available for a wide range of potential contaminants.

B: Test the tips, by lot, on a variety of actual pipettors to ensure they fit properly.

How many companies take all of these steps? Very few. And you can’t be sure a company is taking them, just because their brand name is well known.

#2 Choose a manufacturer who uses automation to eliminate human contact as much as possible.

Loading pipet tips into racks is a tedious process. We’ve all done it. You put on your nitrile gloves, and maybe don a mask. But what contaminants are getting on the tips? Many manufacturers, rather than invest in automation to ensure tips are automatically loaded, produce tips in big barrels which are sent off to low cost-of-labor countries where they are loaded, by hand, into racks then shipped back to the U.S.

#3 Avoid buying tips if you can’t verify their path from mold to market.

Yes, there are very cheap tips being made in China. But this should not be an excuse for just saying ‘no’ to looking at other options. Most tips come out of molds in pristine condition. It’s what happens from that point forward that you should be concerned about.


There are only a few objects coming in contact with your sample – the vessel and the pipet tip. If you want to reduce risk then don’t buy tips if you can’t verify where they have been or you don’t know who makes them. If you want to reduce error, start with the person in the mirror.

And if you are still losing sleep at night trying to decide if saving money on pipet tips might lead to increased error rates, consider that all of these things lend more error to your experiment than the tip you use.

The view is so much better when your head is out of the sand and when the blinders have been removed!

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