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Pipetting innovations drive analytical solution: improvements in pipetting performance in the past 40 years have allowed scientists to obtain more accurate and precise data.

pipettes are one of the most frequently used instruments in the majority of clinical and research laboratories. These essential lab tools are either manual or electronic and the amount of liquid dispensed can range from mL to below 1 [micro]L. Pipettes must dispense liquid precisely and accurately to guarantee truly accurate research results. This article looks at the fundamental features of manual and electronic pipettes and techniques for successful experimentation. It also reviews innovations related to ergonomics and product safety, as well as a recent breakthrough in tip-sealing techniques called interlocking technology. All these innovative product improvements enable researchers to accomplish consistent and precise results from their pipetting experiments.

A look back

Liquid handling has come a long way in 40 years. The following pipetting innovations have enhanced ergonomics and improved accuracy and precision:

* 1970s: The world's first adjustable volume micropipette, first pipette with a finger rest and first multichannel pipettes are developed.

* 1980s: The world's first pipettes with convenient color-coding become available.

* 1990s: The world's first low-ejection force pipette with gearing mechanism that reduces tip ejection forces. The first 16-channel pipette is sold.

* 2000s: The world's first multilingual electronic pipette with full graphical display and a pipette with antimicrobial surface treatment are introduced.

* 2012: The world's first pipette with ClipTip interlocking pipette tip interface.

Advances in pipetting technology have progressed with groundbreaking and innovative biotechnology procedure, that have supported medical science over the decades. Accurate and precise pipettes are paramount for 'ample preparation technologies to speed and simplify preparation of samples and enhance the quality of results for genomics research. It is important to integrate new pipetting technologies into workflows designed to speed discovery of biotnarkers, a key step in understanding metabolic pathways and disease mechanisms, and in identifying potential drug and diagnostic targets. Cell culture processes from growth and passage, to culture and experimentation to final analysis all require reliable piperting systems that provide reproducible and accurate results.

Types of pipettes

Air displacement and positive displacement pipettes are two types of pipettes that have evolved from simple to highly sophisticated instruments. Both pipettes are designed with a piston that moves in a cylinder. Air displacement pipettes are usually reserved for general laboratory use with aqueous solutions, and are estimated to be used by 95 percent of researchers in both clinical and basic science laboratories. Positive displacement pipette models are generally selected fur high viscosity and volatile liquids. .16 draw liquid into the tip of these pipettors, a partial vacuum is created when the pipette plunger moves tip and down the pipette piston. Since there is a volume of air between the piston and liquid, the pressure from the vacuum will draw liquid into the tip. in positive displacement In pipetting systems, the piston is in direct contact with the liquid and will move up when the tip is filling up with liquid.

Electronic pipetting systems have ergonomic and throughput advantages that can reduce pipetring fatigue and save time from the liquid transfer steps. The piston inside the pipette cylinder is operated by a motor instead of manual thumb movement, which reduces the need for muscle force and improves accuracy by eliminating human error. Electronic multichannel pipettes are ideal for demanding lab applications, such as delivering a series of different volumes in any desired order or for mixing after delivery. New technologies are available with features such as an easy-to-read menu, many diluting options and in-lab calibration. State-of-the-art technology used for backlighting smartphones has also been integrated into the design of electronic pipetting systems, giving scientists clear and readable graphical user interfaces.

ClipTip technology

Available for both single and multichannel pipettes are innovations that lock pipette tips securely in place. This advance provides pipetting technology with enhanced accuracy and precision.

Attaching the tips with the same force every time is challenging, extremely subjective and can lead to unreliable sealing. Using an insufficient amount of force with friction sealing systems increases the risk of tips becoming loose, or even failing off. To minimize this risk, researchers often over-tighten the tips. Using extra force requires increased tip ejection force, which can lead to adverse ergonomic conditions, especially on a multichannel pipette where the force can be eight to 16 times the ejection force of a single channel pipette. Additionally, over-tightening tips may cause them to leak due to wearing of the tip cones, creating potential air gaps in the sealing area. In some worst case scenarios, tips have to be detached by hand, increasing the risk of contamination.

A new pipetting innovation, ClipTip interlocking tip attachment technology, overcomes many of the obstacles of traditional friction-based systems. This technology has a locking interface between the pipette fitting and tips that seal by clipping securely into place. The lock eliminates the frustration of loosening tips that may fall off during use and lead to cross-contaminations and loss of valuable samples. This technology enables users to deliver the best possible accuracy and precision for reproducible pipetting with minimal force.

Since a pipette is only as good as its tip, trouble-free pipetting includes choosing a quality rip. Standard pipette tips have evolved from one-type-fits-all applications to multiple categories that include sterile, filter and specialty tips. Filtered tips are generally used to protect pipettes from contamination, which may lead to further sample cross-contaminations. Filtered, sterile tips are most commonly used in, for example, molecular biology applications.

Achieving precise sample delivery requires selecting pipette tips that undergo rigorous quality control and validation to the specifications of the pipette manufacturer. ClipTip technology provides the only pipette tips that clip and lock firmly in place regardless of application pressure. Having a secure seal for every sample with exact sample volumes makes this an essential rip feature to accelerate discovery.

Achieving performance

Biotechnology advancements require more accurate measurements of liquid volume as well as apparatus that can aspirate very small volumes with increased accuracy. How are accuracy and precision defined and what are the factors affecting it? Laboratories are busy facilities with many users sharing pipettes in multiple different protocols, making pipette maintenance paramount for accuracy and precision. in addition to the variance coming from the pipette operator, a number of elements can affect the accuracy and precision of the pipetting results. These elements include environmental factors, like temperature and air pressure, and the properties of the liquid used, such as its density and viscosity. An accurate pipette will aspirate and dispense the true volume as indicated by the volume setting. Precision refers to the reproducibility of the pipetting results. With a precise pipette, the variation of the actual volumes pipetted between different pipettings is low. Most manufacturers will include a calibration report with the purchase of a pi pettor to validate the accuracy of the system. Manufacturers also recommend a hi-annual scheduled calibration process for all users. Online pipette calibration services as well as new calibration features available with state-of-the-art electronic pipettes makes calibration simple.

Manufacturers design indispensable liquid handling instruments to be user-friendly to support productivity for activities such as: reagent addition, reagent reformatting, serial dilutions and reagent mixing. For example, designing a standard curve assay a decade ago would have required time-consuming calculations. En response, electronic pipette models with the "dilution and mix" function offer different pipette speeds and volumes to choose from. Using these innovative features offered with newer models has demonstrated the ability to provide more accurate curves in 20 to 30 percent less time than that required by a manual pipette. Automated instruments also reduce human error and help ensure that data is fully reproducible and reliable.

Minimizing contamination, maximizing ergonomics

Modern laboratories have multiple users at different levels of experience, and establishing internal lab policies to avoid contamination and sample damage is important. Cross-contamination is a preventable problem and can be avoided with lab procedures for autoclaving, deconiaminating and by following maintenance instructions recommended by manufacturers. Many pipette models today are completely or partly autoclavable for sterilizing the parts most at risk for contamination. Manufacturers give clear instructions on the conditions that can be used for autoclaving without harming the performance of the pipettes. Also, most models today are designed to be UV-resistant to enable a less time-consuming decontamination procedure. Using the general guidelines for decontaminating pipettes from radioactivity materials, infectious agents, and organic solvents are also important for employee safety.

Nowadays, there's an increasing demand for ergonomic instruments that will be comfortable to use and reduce risks for repetitive strain injuries (RSI). Pipette manufacturers have responded to this demand by designing lighter weight pipettes that include ergonomic features, such as adjustable finger rests, and require less pipetting forces, reducing pipetting fatigue. An additional ergonomic product feature included in some electronic pipettes today is the trigger-based operation button that uses index-finger action instead of thumb movements, therefore reducing common RSI risks on thumbs.

Improvement of laboratory pipetting performance over the past four decades has resulted in more accurate data, helping scientists solve complex analytical challenges. Daily life science and clinical laboratory work requires frequent pipetting, and the importance of reliable, accurate and precise pipettes is significant. Proper pipette maintenance combined with user-friendly and comfortable, ergonomic instrumentation is essential for consistently accurate sample preparation. Pipetting systems are the most important instruments for transferring liquid in laboratory environment. Understanding new innovative technologies available in liquid handling instruments will aid the researcher to choose the most suitable pipette systems for each application, whether it is the most simple tube-filling need or a complicated, multi-stepped sample preparation workflow.

by Raymond Mercier, Business Director, Liquid Handling, and Suvi Berghall, Product Manager, Liquid Handling Consumables, Thermo Fisher Scientific, Inc., Waltham, Mass.
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Author:Mercier, Raymond; Director, Business; Handling, Liquid; Berghall, Suvi
Publication:Laboratory Equipment
Date:Nov 1, 2013
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