Pipetting of samples and reagents is essential for reliable results. To meet this goal, pipetting has to be done with the highest precision and accuracy, but it must be done safely, without causing undue levels of repetitive strain injuries (RSI) for the lab technician.
In this interview, Dirk Freystadt (DF) (Figure 1), Vice President of Strategic Marketing for the Lab Products & Services Division of Sartorius (Goettingen, Germany), discusses the importance of accurate and precise pipetting in the face of industry trends toward smaller amounts of reagents.
Freystadt also weighed in on how new electronic technology makes pipetting easier and more accurate, and on how new ergonomically correct pipetting designs reduce the risk for laboratory employees, while at the same time ensuring reliable and precise results.
Q: Why is precise and accurate pipetting of samples and reagents so important for achieving reliable analytical results?
DF: Pipetting in the microliter range is a basic laboratory technology in biological, clinical, and analytical labs, used for nearly all processes, including transferring of liquids, dilution, or performing assays, so it is involved in nearly every step taken in a lab. It therefore follows that whenever you are imprecise, or not accurate, it’s going to affect your downstream results. Because pipetting often starts very early in a process, a high mistake or failure rate adds up through the process, and in the end the failure is much higher than it was in the beginning.
Figure 1 – Dirk Freystadt.
And there’s another factor at play—related to the industry trend toward reducing the amount of reagent to save on costs. Using less reagent means sample volumes are getting smaller, but the pipets are not reduced in size because of the physical limitations associated with manual pipetting. This means that whenever there is a failure caused by the operator, it has a higher impact. So the skills and the tools have to be the best that you can get; make sure that your people are trained, know how to do precise and accurate pipetting, and have the right tools to support a high level of precision and accuracy (see Figure 2).
Q: Can you tell us a little more about what you mean by precision?
DF: Precision means when you pipet five times, you are going to get the same volume each time. Accuracy means that you hit exactly the volume that you wanted to hit. When you specify 5 µL, you pipet, and it is 5 µL. You may always be precise, but you might not always hit the right volume. You must make sure you have both precision and accuracy. This is absolutely critical. You have to make sure that the outcome of your experiment is reproducible (even with other pipets and operators) and that the work flow is not harmed by this kind of interaction, whether you’re performing manual, electronic, or automated pipetting.
Q: Can you share your thoughts on how new electronic pipetting technology is improving ergonomics as well as pipetting accuracy?
DF: One of the most exciting technologies to come along in recent years is electronic pipetting. Halfway between mechanical (manual) and robotic liquids handling, an electronic pipet makes pipetting faster and more reliable, with a much lower error rate than mechanical pipetting. It reduces sample volumes while increasing the numbers of samples processed. In addition, beginners can work more safely and efficiently with an electronic pipet.
Concerning ergonomics, the most significant advantage of electronic pipets is actually the reduced force and fewer hand movements required for operation, which reduces the risk of repetitive strain injuries.1
With a mechanical pipet, you may be using your thumb a thousand times per day−some laboratory technicians perform as many as 1000 pipetting operations in a single day. You can imagine that you want to be sure this is done in the right way, at the right angle, and with the right amount of force. If the force is too strong, it can affect the thumb, but if it is too light, you may lose control.
Figure 2 – Pipetting precision and accuracy.
With an electronic pipet, this kind of issue has been taken away, because there is little force and no personal control over using the plunger. The setting of the volume is electronic, and you push the button, and the plunger moves up and down electronically as well.
In the Picus electronic pipet from Sartorius Biohit (Helsinki, Finland), for example, there is an electronic brake and piston control system that can stop piston movement quickly and accurately, guaranteeing high precision, especially during serial dispensing This is an important feature, especially with the smaller and smaller volumes used in today’s pipetting (see Figure 3).
Optical sensors that monitor and control piston movement in real time are another good feature for ensuring accuracy and precision. Electronic tip ejection is a feature that prevents contamination and thus damage to the pipet, and autoclavable parts provide added safety from contamination. It is also an ergonomic feature that reduces the force applied to the operator’s thumb.
Applications for electronic pipets and mechanical pipets
Q: What are the types of applications that benefit most from electronic pipetting and which are best handled with mechanical pipetting?
DF: Electronic pipets are optimal for applications in which a high number of pipetting operations have to be repeated, such as filling microtiter plates. Generally speaking, an electronic pipet should be used for all applications that border on automation. Mechanical pipetting is used most when you have a limited number of different samples, with fewer repetitive steps. Mechanical pipets can be used for transfer of liquids or dilutions, but not for dispensing.
There are a lot of rational reasons for using an electronic pipet, namely accuracy and precision, but there are also emotional factors associated with why people use mechanical pipets. You have to understand, the pipet is the most emotional tool you have in the lab. Because it’s with you all day and every day, it sometimes feels like it is virtually part of your own arm. People feel very safe when they have control over what they are doing, so using mechanical pipets and getting the feedback from the plunger is very important to them.
It may not always be easy for people to upgrade to an electronic pipet, because of this attachment to plunger use. So, the benefits of using an electronic pipet need to be significant enough for people to make this big step. And I would say that these key benefits come primarily from increased ergonomics, the ability to perform dispensing operations, increased speed, and the ease of conducting repetitive activities.
Figure 3 – Picus featuring Sartorius Biohit electronic pipetting technology.
Pipetting ergonomics, service/calibration, and training
Q: Aside from the general trend that reagent volumes are getting smaller, are there other important industry issues that have an effect on pipetting?
DF: The three trends I would focus on are ergonomics, service or calibration, and training. With regard to ergonomics, the issue arises as laboratory workers are pipetting more and more. Some operations cannot be done accurately with automation, so they are being done manually. Some laboratories simply cannot afford automation. Whatever the reason, people are performing pipetting operations manually, and many laboratory employees are pipetting the whole day. If the pipet is not ergonomic and the key ergonomic factor is actually the weight of the pipet—the risk of developing RSI increases, especially carpal tunnel syndrome. The weight is a central issue because you are holding the pipet all day long. And you are not just holding it; you’re concentrating on the sample, trying to move as slowly as possible. This puts a great deal of strain on your hand and the handgrip, and leads to stiffness, which can have a negative effect on the carpal tunnel. So the method of pipetting, the design of the pipet, its weight, and the forces used to push the plunger are very important.
In fact, the National Institute for Occupational Safety and Health identified repetitive pipetting as the most common contributory factor in developing RSI in the laboratory.2 One study3 agreed that pipetting poses the highest risk for getting RSI within a laboratory environment, noting that an astounding 44% of lab professionals suffer from disorders caused by pipetting. According to this study, pipetting for more than 300 hr per year (1.5 hr/day or roughly 6 hr/week) exposes a worker to a fivefold risk of hand and shoulder injuries.
Frequently, laboratory workers think the symptoms “belong” to pipetting work and simply accept them as a given, even as the work becomes very painful. But ergonomically designed, light, and small electronic pipets can ease the pain. For example, the Picus from Sartorius Biohit rests comfortably and optimally in the user’s hand, making it both easy to use and ergonomically sound (see Figure 4).
Q: What trend are you seeing with regard to service and calibration?
DF: The more valuable the sample, the more laboratories need to ensure that their pipetting is done correctly the first time. Some kinds of samples cannot be reproduced, so they might not have a second try.
Here’s where service, in terms of calibration, of cleaning of pipets, makes a huge difference in my opinion. When a pipet comes from the manufacturer, of course it works to specification. But while you are using it, the pipet is getting worn, and after a period of time, it needs cleaning and, eventually, recalibration. Remember the all-important factors of precision and accuracy−you can only be precise and accurate with a tool that has been calibrated properly. The timing of recalibration depends upon the standard operating procedure, or SOP, that has been defined for this process, and may range from four times a year in the pharmaceutical industry to once a year for other industries.
Q: What training trends are you seeing?
DF: In my opinion, training is extremely important to improve both pipetting behavior and ergonomics. Improving the quality of pipetting, by which I mean improving the skills of those doing the pipetting, is critical.
Of course, you can always take a pipet from the box and use it. It appears to be very intuitive, but if you do it incorrectly, you might fall into bad habits, or what I call “misbehavior.” Most of the mistakes I see come from this misbehavior.
I had the same experience myself 20 years ago, when I was working in a laboratory. Imagine you pipet into a 2-mL reaction vessel. You have the pipet in your right hand and the vessel in your left hand. You hold the vessel straight up, and to get a better look into the vessel, you hold the pipet at a different angle. Totally wrong! The pipet should be vertical, and you should tilt the reaction vessel. You could not look at the vessel anymore, but the pipet would be precise, because the pipet is precise when it’s straight up. If you tilt it, then you already have a certain percentage of failure there.
Figure 4 – Lightweight electronic Picus.
I use the example to illustrate that many people are just performing pipetting in a manner that is convenient for them, rather than the correct way. One of the features that I think might develop in the future is designs that ensure that this type of misbehavior cannot happen anymore. I’m not sure how that will play out, whether in the pipet or perhaps in related tools.
So to sum it up, it’s very important that people know how to do pipetting correctly and get the right information, whether it’s from a manual, tools like the Sartorius Biohit Pipetting Academy, or in courses from universities or other educational training companies.
Sartorius Biohit was among the first companies to establish formalized training, and our Pipetting Academy trains customers on how to pipet correctly, how to hold the pipet in an ergonomic way, and how calibration affects pipetting accuracy.
Q: Can you give us an example of the kinds of information lab workers get from the Pipetting Academy?
DF: These tips for lab workers working with pipetting series come from the Sartorius Biohit Pipetting Academy, a training program for improving laboratory health and safety and focused on achieving better results and more comfortable working postures: