The Power of an Expanded Toolbox for Liquid Handling

When researchers think about liquid handling, the main focus is usually throughput. But liquid handling is affected by a host of other factors. Researchers must contend with a wide range of liquids differing in properties such as viscosity, volatility, and toxicity. They also need to balance accuracy and precision demands alongside throughput and cost efficiency. Finally, liquid handling workflows can create ergonomic strains on scientists. As such, scientists should take care to identify and obtain optimized solutions for their specific situations and needs.

The Importance of Comfort

The micropipette is the workhorse of the typical life science laboratory, and it represents the primary point-of-contact for most scientists with liquid handling. As such, handling and using the instrument is a major source for potential ergonomic issues. Micropipettes should ideally be lightweight and intuitive; designed so that they can be used with a natural-feeling grip. Moreover, tip insertion and ejection should be smooth, as excessive force here can create strain on the instrument, hand, and arm.

Fortunately, ergonomic considerations are becoming front-and-center when designing all-purpose micropipettes. For example, the Eppendorf Research® plus is designed according to the Eppendorf PhysioCare Concept®—seeking to optimize the interactions between instrument, work environment, and user. The Research® plus strives to reduce operator strain by decreasing instrument weight and operating forces. It does this through a spring-loaded tip cone that maximizes tip tightness while minimizing the required attachment force. This technology also helps ensure consistent tip pick-up and seal even in multi-channel pipettes.

Strategies for Different Solutions

Liquid handling in the life sciences means working with more than just water-based solutions. Researchers commonly encounter substances that are difficult to fully dispense due to high viscosity such as glycerol or detergents, or volatile substances such as organic solvents that leak from pipette tips. Scientists can handle these situations by employing different pipetting techniques. For example, pipetting more slowly than usual improves aspiration and dispensing accuracy when working with viscous substances. Pre-wetting the tip—a strategy where a pipette tip is rinsed by aspirating and dispensing the desired volume multiple times—can decrease leakage when working with volatile reagents. Finally, reverse pipetting—where a greater volume is aspirated than dispensed—can offer more precision when working with small volumes or liquids that tend to foam.

Automation takes these strategies into consideration, with today’s electronic pipettes offering pre-established settings corresponding to these techniques. For example, the Eppendorf Xplorer® electronic pipette has pre-set modes for forward pipetting, reverse pipetting, and creating dilution series, among others. It also offers a lower and more controlled flow speed compared to manual pipetting, helping to reduce potential shear stress damage to delicate elements within solutions, such as cells and nucleic acids, during liquid handling.

Moving Workflows Forward

Transferring aliquots from a larger reservoir to smaller vessels is a very common liquid handling procedure, especially for PCR applications. However, repeating this process with each well in a 96- or 384-well plate is highly labor intensive. Further, while multi-channel pipettes strive to streamline this process by enabling researchers to perform multiple pipetting operations at once, they do not always have the flexibility to accommodate discrepancies in well size and spacing. For example, a 96-well plate for real-time PCR and a 96-well plate for enzyme-linked immunosorbent assays (ELISAs) will have different well diameters and spacings.

Considering this, the latest multi-channel pipettes can now be equipped with adjustable tip spacing. Eppendorf’s Move It® pipette lets operators set the distance between pipette tips in 1 mm increments between 4.5 and 33 mm. It is also equipped with pre-defined settings for rapid toggling between commonly used formats within the laboratory. The Move It® pipette exists in 4-, 6-, 8-, and 12-channel varieties and is compatible with both Xplorer® electronic and Research® manual pipettes.

A Pipette for Each and Every Situation

Liquid handling is a fundamental day-to-day aspect of life sciences laboratories, but this has arguably caused scientists to take it for granted. There is no “one-size-fits-all” approach to liquid handling, but there are a wide range of tools, technologies, and techniques that scientists can harness to take their liquid handling workflows to the next level in terms of accuracy, speed, and comfort.