Pipettes are an essential tool in the laboratory. This is the case no matter the sophistication level of the lab that’s in question. In this article we’ll explore the best way to use pipettes, the history of pipettes, types of pipettes, and how they are applied in a lab setting.
What Is a Laboratory Pipette?
Pipettes are multipurpose tools that allow lab professionals to appropriately transfer or measure liquids in the lab. They are piston-driven instruments that look like syringes, and come in a variety of designs. Pipettes can range from single-piece glass pipettes to electronic pipettes. These different types of pipettes vary in terms of accuracy, precision and design, and can be either hand-operated or automated. Researchers should be mindful of what specific tasks they need pipettes for before they select pipettes.
How Do They Work?
Most pipettes work via an air vacuum that makes it possible for the pipette to draw up and expel liquid. The part of the pipette known as the plunger then has pressure put on it which causes fluid to go into the tip of the pipette. For the liquid to be let go from the chamber part of the pipette and out its tip, more pressure has to be applied to the plunger.
The History of Laboratory Pipettes
As a concept, pipettes have existed for over a century. However, it wasn’t until 1957 that a pipette model was patented by the German scientist Dr. Heinrich Schnitger, founder of the laboratory equipment maker Eppendorf. The commercialisation of pipettes started with Eppendorf’s sale of micropipettes which quickly became widely endorsed by laboratories.
Adjustable micropipettes are said to have been created by American inventor Wareen Gilson and biochemistry professor Henry Lardy. These pipettes vary both in size, functionality and volume capacities.
Micro and Macro Pipettes
The point of micropipettes is to improve precision. They help properly remove and distribute liquids in the microlitre range. The capacity of a micropipette can range from 1 to 1000 microlitres. For greater quantities, macro pipettes are used. Their capacity can range from 0.25 – 5mL.
Lab Pipette Types
Manufacturers have designed different pipettes for a wide variety of uses over time. Accuracy and precision between pipette models vary greatly because of their different designs. Here is a list of pipettes that are commonly used in the laboratory:
Single-channel pipettes
Single-channel pipettes can be used for a myriad of purposes. They are also known as variable volume air displacement pipettes. The range of volume capacity they offer can be between 0 to 2500 microlitres. Both adjustable and fixed-volume single-channel pipettes can be of great use to lab professionals.
When small containers need to have liquid drawn out of them or need to be filled with liquid, single-channel pipettes are the most suitable instrument.
Good single-channel pipettes are ergonomic. A user should be able to make the most out of them in a way which is not strenuous. Repetitive strain injury can be avoided this way.
When using single-channel pipettes you can only transfer one liquid at a time. This can mean that performing some tasks with these instruments can be difficult and time-consuming.
Multichannel pipettes
When doing repetitive tasks, multichannel pipettes are superior to single-channel pipettes. This is because these pipettes usually have 8 to 12 heads and make it possible for researchers to move a range of liquids at the same time.
Multichannel pipettes’ ability to reduce the amount of times liquids need to transfer individually makes some scientists opt for them when doing cell culture research.
Multichannel pipettes reduce the amount of times lab personnel have to individually transfer liquids, but they don’t completely stop scientists from incurring repetitive strain injuries. However, if multichannel pipettes have spring loaded tips they are less likely to cause hand injuries. Overall, these pipettes improve any laboratory task they are used for.
Electronic pipettes
Repetitive strain injury is an issue that is regularly encountered by researchers in the lab. Electronic pipettes automate the air displacement process, reducing the likelihood of strain. They can perform the same exercises that hand-operated pipettes can without putting so much stress on the hand. Multi dispensing is when reagents have to be divided, this is when electronic pipettes are the most appropriate pipettes to use.
Electronic pipettes also come in handy because they can be programmed to suit specific tasks. This can help improve the effectiveness of tasks being carried out in the lab. Electronic pipettes offer adjustable tip spacing which helps professionals move multiple liquids.
Not only do multichannel electronic pipettes make use of multiple heads to help improve performance, but they are also ergonomically designed. This makes for maximum comfort when lab professionals are microplate filling. A lot of tasks can be done in less than one minute.
Serological pipettes
Generally these pipettes are made from glass or polystyrene. Researchers that are mindful of sterilisation will use these disposable pipettes that are made of durable plastic. They are also usually used when liquid dosages are more than 1mL.
Manual Stepper pipettes
When it comes to simple tasks or tasks that need to be done multiple times, the Manual Stepper pipettes are very helpful. The tool has a dispensing range of 5 mL. Liquids that change a lot or are harsh are best to be handled using Manual Stepper pipettes because the pipette relies on the positive displacement principle.
Selecting the Appropriate Pipette
You should make sure to choose the right pipette before carrying out any task. Depending on what model is being used, pipettes differ in terms of functionality. Consider these factors before selecting the appropriate pipettes:
- Consider what type of tasks you will use. Does it prioritise speed, accuracy or precision?
- The type of liquid you plan to be transferring. How harsh is it? Is it harsh enough to damage the pipette that is being used?
- What is the operator recovery time supposed to be between sessions? It might be that whoever is conducting a task should be expected to take breaks or switch with lab partners at regular intervals.
- How repetitive is the task? The more repetitive the tasks, the more likely it is that ergonomically designed pipettes should be used. They reduce the stress on your hand, and therefore affect the accuracy and precision achieved when using pipettes as well as reducing the risk of injury.
- What’s your budget? This will affect the type of pipette you can get. Electronic pipettes are usually more expensive than manual ones. For this reason, they are less likely to be found in technical laboratories.
- Read the instruction booklet. This is an important step to take before using all pipettes. Pipettes can be the same type but still vary slightly from model to model. Personnel in the lab should be conversant with all the pipettes used in their lab setting. Lab personnel not having adequate pipette know-how will not only hinder the performance of lab work, but will also cause health and safety issues.
Technique is important when pipetting. The common errors that arise when pipetting are mishandling of pipette tips, rhythm or timing. Some lab professionals might even make the mistake of using the wrong pipettes. Other errors researchers often make is not using the right volume pipette for a particular task and using an air displacement pipette when handling nonaqueous liquid. A positive displacement pipette should always be used when it comes to viscous fluids.
There are a few things that should be considered before pipetting procedures are carried out. The type of experiment at hand, the type of liquids that are involved, and the desired throughput, should all be factored in before a pipette is selected. Once you have the right equipment, the next important thing to be done is conducting the right procedures.
Steps When Using an Air-Displacement Pipette
These steps, when followed properly, help improve how accurately and frequently a specific volume can be measured:
- Adjust the volume on the pipette
- Depress the plunger.
- Make sure to immerse the tip of the pipette to the correct depth. This can differ based on the pipette and the tip. Place the plunger cautiously to its resting position.
- Stall for a second so that the liquid could rise to the tip of the pipette slowly.
- At 10-45 degree angle put the pipette aside the barrier of the container that is receiving the liquid and gradually depress the plunger to the first stop.
- Before you depress the plunger to the second stop, wait for a second.
- To withdraw the pipette, slide the tip up the wall of the container.
- Then let the plunger be in its rest position
When it comes to an electronic pipette a lot of the above steps are automated, volume can often be easily adjusted via a digital display, and a motorized piston allows for aspiration and dispensing that gets most of the job done. Researchers can use preset programs and custom modes to create their own set of instructions.
Pipettes play a pivotal role in laboratories. At Techmate we have different pipettes available for you to choose from. You can browse through our catalogue yourself or contact our team to help you pick out a pipette or any other lab supply you are looking for. We are confident we have something in store for you that will make a great difference to your lab work.
