Multichannel pipettes - the easy way to increase productivity

With the use of microtitre plates increasing to keep up with productivity demands, the need for multichannel pipettes has never been greater

Growth of the drug discovery market and techniques such as serological testing, molecular biology, immunology assays, high throughput screening and polymerase chain reaction have rapidly expanded the use of microtitre plates. The nature of such work, the need for increased productivity whilst still maintaining accuracy and precision, plus the desire to reduce repetitive strain injuries (RSI), have heightened the demand for ergonomic, highly accurate and precise multichannel pipettes. The need to easily maintain these important instruments and adhere to quality legislation has also become critical.

Demands on scientists to produce valuable research, publish papers and justify funding are high. The pressure to increase productivity is ever growing, while the demands to maintain experimental accuracy and reduce the risks of personal injuries to scientists still remain a priority. These pressures necessitate reliable, easy to use laboratory equipment that can improve efficiency and whose performance can be certified.

Multichannel pipettes have been available for many years but have been notoriously tricky to use. Difficulties in tip loading, inconsistent sample loading and heavy tip ejection forces cause frustration. Such problems have restricted their use particularly for 12-channel pipettes. Recently new developments have overcome these issues opening up the use of multichannel pipettes as user friendly, proficient productivity improvers.

Minimise Pipetting Steps with Multichannel Pipettes
Most experimental work starts in individual tubes for which single channel pipettes are ideal. Once protocols have been established the next step is to scale up the research and run larger scale pilot experiments or assay runs, often performed in 96 well microtitre plates. Utilising single channel pipettes at this stage can be extremely time consuming and highly repetitive.

How many pipetting steps?
Have you ever thought about how many pipetting steps it takes to set up a 96 well PCR plate? For example, using a manual single channel pipette it can take as many as 672 individual steps (7 reagents x 96 wells). This amount of pipetting, even with an ergonomically designed single channel pipette can cause hand fatigue and increased risk of RSI, even with correct pipetting technique. If your hands are tired, errors can be introduced that could have detrimental effects on accuracy and precision. This may result in the need to run the plate again, not only wasting valuable reagents but also decreasing productivity and so reducing the advantages of using the 96 well plate in the first place. Microtitre plates are the reason why multichannel pipettes were designed. A manual 8-channel pipette can fill an equivalent 96 well PCR plate in only 84 pipetting steps. A manual 12-channel pipette can further reduce this to only 56 pipetting steps. [Figure 1]. These reductions have a significant impact on time savings, reducing the risks of RSI, maintaining the accuracy of pipetting and improving laboratory productivity.

Figure 1. Multichannel pipettes can increase productivity.

The number of pipetting steps can be dramatically reduced again by using an electronic 8 or 12-channel pipette which has a multi-dispense, autopace function, bringing a level of automation to the bench top. For example with the Rainin EDP3 8 or 12-channel 1200µl pipette from Anachem [Figure 2], when using a PCR master mix containing a hot start Taq polymerase, only one click to aspirate and one click to dispense is required to fill a 96 well PCR plate. The time taken to fill the plate is also greatly decreased when using electronic multichannel pipettes and they often provide a wide range of features such as multi dispense, mix, titrate, fixed and standard pipetting. Modern battery technology means 3000 pipetting cycles can be performed on one charge.

Figure 2. Rainin EDP3 electronic multichannel pipette

Multichannel Tip Fit
An essential element of efficient multichannel pipetting are the tips used and their fit with the pipette. Many pipettes on the market require excessive force to apply tips across all channels or time consuming manual adjustments before use. Researchers often resort to “rocking” the manifold over the tip rack, then hand-tightening each tip in an effort to secure a proper seal. These tedious methods can result in loss of productivity and possible contamination. Tips that are jammed onto pipette shafts can also be difficult to eject causing greater hand strain to the user. Poorly fitting tips cause inconsistent loading, samples and reagents are wasted, and in many cases, work must be re-done. Care should be taken when choosing a pipette and tips to ensure that the benefits of the multichannel are not being hampered by ill-fitting, poor quality tips.

To overcome this problem, Anachem lauched the Rainin Lite Touch Tip Ejection (LTS) range of Electronic and Manual multichannel pipettes. The makers say that the pipettes load tips and seal in as little as two seconds, where traditional multichannels can require up to 30 seconds.

Unique New Multichannel Calibration Options for ISO8655 Compliance
As with all liquid handling devices, regular performance testing and calibration of multichannel pipettes is essential to ensure their accuracy and precision. Potential problems must be identified and corrected before they impact the integrity of laboratory data. For accurate and reliable testing, a laboratory needs to have qualified, experienced personnel, properly calibrated test equipment and a controlled test environment. Proper sampling and sound test procedures with traceability are as important. In short, the testing laboratory should have the full competence to perform calibration according to international standards.

EN ISO8655:2002 has become an international standard that unifies the wide variety of different standards and recommendations for Piston Operated Volumetric Apparatus (pipettes). It clearly states the pipette specifications, both for manufacturers, technical services and users, the testing methods, testing conditions, and even the influence of different sources of error in pipetting. Most laboratories today are ISO 9001 or GLP certified and the trend is to obtain accreditation, too. ISO 8655-6 outlines the specifications and testing methods by which multichannel pipettes are calibrated/validated. It states, “For the purpose of the test, each channel shall be regarded as a single channel and tested and reported as such.”

So, to comply with the standard, multichannel pipette performance testing should be carried out on each and every channel. Although activated by the same operating mechanism, by testing every channel, this ensures that each liquid end is behaving within the same parameters and that the maintenance across all channels is complete.

However, full calibration on every channel can be extremely time consuming. A standard 2.2 calibration on a 12-channel pipette requires 48 pipetting cycles and gravimetric weighings (2 volumes x 2 repetitions x 12 channels). When performed manually each of these measurements can take approximately 2 minutes– a total of over 1.5 hours to calibrate just one pipette. For laboratories requiring UKAS (United Kingdom Accreditation Service) calibration, a total of 360 gravimetric weighings (3 volumes x 10 repetitions x 12 channels) would be needed. Performing this number of tests manually becomes impractical and prohibitively expensive.

However, to overcome these problems pipette calibration services are available from several companies, for example, Pipette doctor, alpha laboratories and Anachem.

Today’s innovative pipette designs and service options mean that it is possible for scientists to maximise the use of multichannel pipettes to improve their productivity without the loss of accuracy or precision.

by Carole Staniford, Marketing Manager, Anachem Bioscience, Charles Street, Luton, LU2 0EB, UK.