A serological pipette is an important equipment in the serology laboratory. Serology is a science that studies in vitro antigen-antibody reactions conducted in the laboratory to aid in rapid diagnosis of diseases among other uses. The tests are sometimes called immunological rapid tests.
These tests usually check if there is an immune response to a specific antigen. the tests can take a very short time to perform and report the results. That is what makes them very popular.
Although these tests don’t need a lot of skills to perform, they need good skills to report because they can show false negativity/positivity if due care is not taken. Hence, they should be performed by highly trained laboratory clinical immunologists.
In this article we shall discuss what serological pipettes are, the different types of serological pipettes, how they are used, and quality assurance in the use of these pipettes.
What is a Serological pipette?
A serological pipette is a glass, but mostly plastic graduated laboratory equipment that you can use to measure small volumes (in milliliters) when performing laboratory tests.
Most of pipettes are made from transparent medical grade polystyrene. The pipettes are normally irradiated by gamma to make them sterile before they are released to the market.
Serological pipettes are sometimes referred to as blow-out pipettes. This name emanates from the fact that you must blow them out using their attached bulb-like filler to expel all the fluid contained therein.
Serological pipettes are standard in the sense that they all can fit into any serological pipette filler (bulb-rubber). Fitting a serological pipette to the bulb-rubber filler enhances efficiency in volumetric measurements.
This, also, certainly brings convenience on the part of the user when making the measurements. The pipettes form part of the equipment that is almost synonymous to a serological laboratory – always present therein.
A serological pipette can be sterile or non-sterile, class A or class B, and may be classified as pipette meant to deliver or to contain. We shall get to further understand about these terms when we describe specific serological pipettes.
What are Serological pipettes used for?
Serological pipettes can really simplify measurements if they are well used. However, wrong use of these equipment perhaps because of some sort of ignorance on their accurate use can mess up the measurements.
There is, therefore, the need to learn how to use serological pipettes. A serological pipette can be used in various ways as highlighted here.
Serological pipettes are useful in:
- Transferring cell colonies from broth (liquid culture medium) to a different container as the process of isolation and identification of cells continues.
- Serological pipettes are extremely important when making serial dilutions where you can use them to transfer liquids from one tube to the other in the series. This makes the making of serial dilutions efficient and easy.
- Serological pipettes are used to transfer and mix cell suspensions during experiments in the laboratory
- You could also use them to mix reagents before your main experiments or as part of the testing process.
- Used to transfer solutions of DNA/RNA structures during DNA analysis and in forensic serology.
How to Use a Serological Pipette
When it comes to operating this laboratory equipment, it is one of the simplest to operate. You only need to immerse the tip of the serologic pipette into the solution you want to transfer.
Then squeeze the rubber to create suction pressure which when you to start release will allow the fluid to get into the pipette up to the level you want.
For fixed-volume pipettes you release the bulb-like rubber filler completely to allow the pipette to fill to the maximum. Just release it gradually to ensure that no air bubbles are trapped in. Trapped in air will most likely cause an error of insufficient volume.
Quality Control in the Use of Serological Pipettes
Under this subheading we shall discuss two issues that can make the measured volumes turn out to be inaccurate.
1. Wiping the pipette tip
There is need to wipe the outer side of the serological pipettes after dipping the pipette into the solution. As we’ve already stated, these pipettes measure volumes in milliliters. Therefore, not wiping the outer side with an absorbent material would increase the margin of error especially when measuring viscous fluids.
But you need to be careful to check the meniscus level again after wiping because if you accidentally touch the mouth of the pipette, you could absorb some fluid from the inside of the pipette.
2. Calibration of Serological Pipettes
For quality reasons, it is important for you to calibrate pipettes in a routine manner. This is because of the small volumes that these pipettes measure, where a small error can greatly affect your measurements in the laboratory.
However, since serological pipettes are not adjustable, they are not calibrated. They are single use pipettes and so chances of losing the accuracy of the scale is very minimal if the manufacturer and/or product is known to be credible.
Types of serological pipettes
There are generally three types of serological pipettes, and they are all made of polystyrene plastic or glass material. They are all single-use pipettes that are discarded once used to minimize chances of carry-over contamination. Let’s now describe the three types of serological pipettes here.
1. Aspirating Pipettes
Aspirating pipettes are for mixing fluids during experiments or laboratory tests. To avoid possibility of carry-over contamination these pipettes are designed to be single-use equipment then discarded.
Like other types of serological pipettes this type is non-pyrogenic, gamma-sterilized, and well packaged to ensure they are not contaminated after leaving the companies where they are manufactured.
2. Open-ended Serological pipettes
These serological pipettes have fiber filter plugs meant to minimize contamination. They are sterilized, non-pyrogenic pipettes that are quite popular in serological laboratories. Their packaging is further specially designed to prevent contamination.
Open-ended pipettes are specialized for measuring fluids that highly viscous. They are particularly useful when you are transferring fluids like paints, oil, and sludge among others. We believe their open-end design helps enhance their suitability for these fluids.
The open-ended pipettes come in many sizes including 1 mL, 2 mL, 5 mL and 10 mL pipettes. Some manufacturers may have even bigger capacity pipettes than the ones listed here like 25ml and the 50ml serological pipettes.
3. Bacteriological Pipettes
This type of pipettes is used to transfer and mix fluids like milk when testing for the presence of bacteria. As you would expect the pipettes are sterile and non-pyrogenic sterilized by strong gamma rays.
Different manufacturers make them in different volume capacities. The most common pipettes sizes here include the 1.1 mL and 2.2 mL capacities. However, the other higher-capacity serological pipette may be available.
Reading and Reporting the Volume of a Serological Pipettes
This step is critical because if not well done can yield serious errors. Though it can look easy, this is not an activity for every Tom, Dick, and Harry. You can mess up tests and mislead diagnosis if ignorant.
Expertise in reading meniscus is needed here. What you should do is to lift the pipette, hold it at the level where your eyes are looking at the meniscus horizontally. Your eyes at the same level as the meniscus.
Further, the pipette should not be twisting but should be vertically upright from the ground. For quality reasons and to ensure that there are minimal errors you shouldn’t rely on a single measurement.
Repetitive measurements can help in enhancing accuracy. At least three measurements can help you build confidence of accuracy if there is consistency in your measurements.
Conclusion
A serological pipette is a vital equipment in a serological laboratory without which measurements cannot be done accurately. There are three common types of serological pipettes that include aspirating, open-ended, and bacteriological pipettes.
Very impressive one Sir 🙏
great work, very educative.
Thanks a lot Mr. Maina
Detailed and useful information.. Thank you
Thank you too for your positive comment