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Although there is an initial investment when purchasing automated liquid handling systems, costs can be recovered quickly. This is achieved through more efficient use of manpower, overcoming repeated experiments due to errors, and by preventing product rejects. Additionally, the intelligent burets help avoid using the wrong solutions by giving a warning before the experiment starts.
Automated liquid handling – The key to accurate and reproducible results
May 20, 2024
Article
Liquid handling is one of the most important (yet tedious) tasks in the analytical laboratory. However, analytical results are only accurate and reproducible when using the correct volume of sample, solvent, reagent, titrant, or auxiliary solution. With each manually prepared sample or solution, the risk for falsified results rises. This blog article discusses the many advantages of automating liquid handling steps.
What is automated liquid handling and what equipment is needed?
The main concept of liquid handling is to transport a solution or reagent completely, accurately, and precisely from one place to another. Contrary to manipulating liquids with e.g., graduated cylinders, glass burets, or pipets, automated liquid handling utilizes piston-driven burets to perform this job.
A piston-driven buret from Metrohm consists of three major parts: the piston, cylinder, and dosing drive (Figure 1). Inside of the buret is a piston which is mounted in a cylinder. The piston is coupled to the spindle of a motorized dosing drive that moves the piston up and down within the cylinder.
Figure 1.
Illustrative cross-section of a piston-driven buret from Metrohm.
Depending on the dosing device used, the drive can be mounted as shown in Figure 1 or turned by 180°. In the example shown here, liquid can be aspirated through the IN port when the piston goes down. Conversely, liquid is dosed through the OUT port when the piston goes up. A valve disk is used to switch between these ports.
Figure 2.
Metrohm 807 Dosing Units come in various sizes from 2 mL up to 50 mL.
Flexibility of dosing devices
Metrohm offers dosing devices that can handle either exchange, dosing, or cylinder units. Metrohm burets e.g., 807 Dosing Units, come in various sizes from 2 mL up to 50 mL (Figure 2).
Depending on the application, different materials are used to best suit the specific task. Glass cylinders (Figure 2) are used for general purpose liquid handling, while ETFE 807 Dosing Units (Figure 3) are used for more aggressive chemicals e.g., for dosing alkali reagents or hydrofluoric acid (HF).
Figure 3.
Example of an 807 Dosing Unit ETFE (5 mL) used for dosing aggressive chemicals like hydrofluoric acid.
Flexibility of control means that these burets can be used for various liquid handling tasks, e.g., the addition of titrants or auxiliary solutions, pipetting, diluting, sample preparation, and much more. This flexibility allows automated liquid handling to be used for many different applications like sample measurement, sample preparation, dilution, and standard addition for analysis techniques such as titration or ion chromatography (IC).
It is very useful to work with automated liquid handling devices in all kinds of industry sectors like pharmaceuticals, petrochemical refining, chemical manufacturing, environmental analysis, and more. Whenever an exact, known amount of a liquid must be used, automating this work is a must for the most accurate and dependable results.
Read our blog post to learn more about automated liquid handling solutions for the petrochemical industry.
Lab of the future: Automated robotic analysis of petroleum products
Benefits of using automated liquid handling
Automating liquid handling tasks can dramatically improve your daily lab routine. The following benefits are gained when manual liquid handling practices are automated.
Liquid handling tasks are completed more quickly or even completely automatically, allowing you to focus on other more demanding tasks. For example, an eluent can be mixed automatically at the touch of a button, or even an entire series of titrations can be processed overnight without the need for lab personnel.
How can you save money by using automated titration systems? Read our blog post to find out more.
Automation of liquid handling steps allows potentially hazardous or toxic substances to be handled more safely, as direct contact with these substances is minimized. The solution is added to a bottle to which a dosing device is attached. When the solution is required, the user only needs to press a button.
Whether the dosing device is used for the addition of titrant, reagent preparation, or accurate aspiration of a sample solution, it has a direct impact on the analysis results. This is mainly due to the much smaller dosing steps that can be made with an electronic piston-driven buret in comparison to other manual technology that can only provide the solution dropwise.
The pharmaceutical definition of a drop is equivalent to approximately 50 µL. This volume sounds quite small, but it is actually 6000 times greater than the smallest possible dosing steps (0.008 µL) achievable with a modern electronic buret.
Additionally, the results from using standard glass burets and measuring cylinders for manual liquid handling tasks are highly dependent on the person reading the volume and handling the equipment. With an electronic buret, the volume is measured automatically and the result is displayed digitally. This ensures a high degree of objectivity for the results.
Learn more about the main error sources from liquid handling practices during manual titration in our related blog post.
Why your titration results aren’t reproducible: The main error sources in manual titration
Using automated liquid handling enables more precise documentation through tracking of all dosing steps. This is particularly important in regulated industries such as pharmaceuticals, biotechnology, and for food and beverage manufacturing. Through automatic data acquisition of e.g., reagents used, volumes, time, and other relevant parameters, a complete record of the experiment is obtained. Overall, this helps to improve data integrity, fulfill compliance requirements, and increase the efficiency of laboratory processes.
The majority of Metrohm burets have a chip implemented that saves all information about the solution, its titer, the validity, and expiry date, to ensure the experiment will only be carried out with the correct solutions and conditions.
Conclusion
If you are still working manually with pipets, glass burets, and other kinds of measuring cylinders in your lab, it’s time to consider automation for your liquid handling processes. These days, electronic burets can do much more than just simply transfer a liquid from one place to another. Accurate, precise, cost-efficient liquid additions and sample preparation are only some of the benefits of switching to using automated liquid handling in the laboratory.
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