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In a digitally fast-paced dynamic world of laboratory research, the parameters of precision, accuracy, and safety are paramount. Each and every drop of reagent matters and precaution against exposure to hazardous materials counts.
That is where efficient equipment/instrument or tool are indispensable since they optimize the way liquids are handled in laboratories across diverse areas such as biotechnology, pharmaceuticals, chemistry testing.
Precision and accuracy are priorities, particularly when dealing with micro- to low-milliliter volumes. The success of experiments and the reliability of results hinge on the meticulous handling of liquids.
A wide range of instruments/equipment are available to navigate the variety and it is essential to understand how these tools work and their suitability for specific applications. When it comes to low to medium throughput liquid handling, two primary categories of instruments are commonly used: air displacement pipettes and positive displacement pipettes.
Air displacement pipettes
Air displacement pipettes are used in most labs and for a wide variety of applications and are the ‘workhorse’ of the lab. As the name implies, a column of air does the actual work of moving the liquid with these instruments. The piston in the pipette moves an air column which allows liquid to be drawn into a disposable tip and then dispensed out.
With an air displacement pipette, there should never be any direct contact between the liquid and the pipette or piston. If liquid is drawn into the pipette at any time, the pipette must be cleaned before further use to maintain proper performance and accuracy.
Air displacement pipettes excel when handling liquids with characteristics similar to water. With proper technique and a well-fitted tip, they offer remarkable accuracy. However, as the physical properties of the liquid deviate from those of water, such as differences in density, viscosity, or vapor pressure, the accuracy of pipetted volumes decreases.
These pipettes can be operated manually or electronically. Manual air displacement pipettes, such as the brand Transferpette S, comes in both single and multichannel variations. Single channel pipettes can have fixed or adjustable volumes, spanning from 0.1 µl up to 10 mL. Multichannel manual pipettes are available as 8-channel or 12-channel models, with volumes ranging from 0.5 µl to 300 µl.
Electronic air displacement pipettes offer the advantage of minimizing user-to-user variability. Electronic control of piston movements reduces the physical effort required during pipetting and making it a valuable equipment for laboratories with medium throughput pipetting needs.
Positive displacement pipettes
Positive displacement pipettes differ significantly from their air displacement counterparts. They allow direct contact between the liquid and the pipette piston, offering greater accuracy when handling liquids with diverse densities, viscosities, and vapour pressures. Unlike air displacement pipettes, which require liquids similar to water in physical characteristics, positive displacement pipettes can accurately handle a wider range of liquids.
Positive displacement pipettes are particularly valuable when accurate dispensing of partial volumes is essential. For multi-dispensing of partial volumes with precision, a positive displacement pipette is the ideal equipment.
The brand Transferpettor is an example of a manual positive displacement pipette, and is available in volumes from 100 µl to 10 mL. It can be used for dispensing viscous or volatile liquids that cannot be accurately dispensed with an air displacement pipette.
The tips and piston seals for the ‘Transferpettor’ are reusable, and the piston seal is designed to push the liquid entirely out of the tip, minimizing carryover between samples.
A specialized version of positive displacement pipette is the repeating pipette. This is a category of positive displacement pipettes that is specifically designed to handle multi-dispensing of partial volumes accurately. The brand ‘HandyStep S’ has nine step settings (1 to 5 with ½ settings) which allows for dispensing volumes ranging from 2 µl to 5 mL – depending on the size of the tip.
Electronic repeating pipettes, such as the brand ‘HandyStep touch and touch S’, offer much more versatility than manual repeating pipettes through flexibility in volume setting, more options in functionality, and touchscreen operation. With the electronic repeating pipette, it is possible to perform auto-dispensing, sequential dispensing, multi-aspirating, and even titration.
Since the piston movements are electronically controlled, there is a wide range of speeds for both aspiration and dispensing, which is helpful for liquids that tend to foam or bubble. Additionally, an electronic instrument reduces strain due to repetitive motion, which can be an important consideration when performing repeat dispensing for long periods of time.
Automated liquid handling
When a lab’s throughput begins to increase, or for other considerations, an automated pipetting system may be the appropriate tool. Liquid handling automation differs from handheld pipetting in that it uses a robotic system to move liquid from a source to a destination.
Some systems, like the brand liquid handling station, use air displacement liquid ends which are suitable for many types of liquids. They can compensate for liquids that would be a challenge with manually operated air displacement pipettes. The volume range for pipetting robots can range from nanoliter to milliliter volumes.
Manual air displacement pipette
Manual air displacement pipette is the workhorse of the lab. This is the ‘go-to’ instrument for most people. With volume ranges from 0.1 µl to 10 mL it can handle many tasks and a variety of liquid types.
If user-to-user variability or repetitive strain are a concern, then an electronic air displacement pipette should be considered. When pipetting viscous or volatile liquids or performing accurate repeat pipetting, a positive displacement pipette is the instrument of choice.
Finally, if the laboratory has increasing throughput, needs to improve repeatability, or simply wants to optimize processes, it may be time to consider automation.
Choosing the right dispenser
When selecting a dispenser, considerations such as the type of reagent and compatibility with laboratory protocols are crucial. Different instrument models cater to specific needs, with options available to suit various chemical compositions and applications.
By investing in quality instruments like brand ‘Dispensette S’ dispensers, investors/researchers ensure long-term reliability and performance in their laboratories.
Separation technology is often an important element in laboratory-based research, development, analytics and diagnostics across all major applications and workflows.
At the heart of laboratory workflows, accurate and efficient equipment is crucial tools for controlled handling of liquids. Unlike traditional glassware like graduated cylinders and volumetric flasks, precision dispensers operate on the principle of positive displacement. This means that the volume dispensed is precisely what is delivered to the receiving vessel, ensuring the highest level of accuracy and reproducibility.
Conclusion
Accurate and precision laboratory dispensers offer researchers a safer and more efficient means of handling liquids. Selecting the appropriate equipment/instruments is crucial for the efficiency and reliability of a laboratory system.
Each laboratory technology has its advantages and limitations, making it essential to consider the specific requirements of the application. A modern laboratory in pharmaceutical sector is significant and it needs high precision equipment.
A wide number of instruments are used in pharmaceutical laboratory for quality control. Selection of correct laboratory equipment is very important to get the right process and product that will perform for the right price with fast and efficient service.
Laboratory equipment in pharmaceutical sector have great significance as that in chemical and other process sectors, rather it is more important in pharmaceuticals, which needs sophisticated equipment for analysis of samples for quality control purpose.
(The author is a retired chemical engineer)
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