by Sari Mannonen, Pasi Nieminen, Jukka Kaasinen and Kati Andersin
Multichannel pipettors are widely used in microplate work, including serological testing, molecular biology, immunology assays, and polymerase chain reaction (PCR). The explosion of specific markets such as genome projects and drug discovery has further increased the use of the microplate. Because microplates are currently being used in very labor-intensive applications worldwide, there is a need to increase productivity, maintain accuracy and precision, and reduce physical stress. Each of the approximately ten multichannel pipettor manufacturers emphasizes ergonomics, comfort, ease of use, and safety. Despite this, many users have problems with performance, tip mounting, tip sealing, and tip ejection. The key question is: How does one choose the correct multichannel pipettor? Following are a few criteria that should be considered when choosing a multichannel pipettor.
All manufacturers claim that their pipettors are ergonomic. However, there exist clear differences in pipetting and tip ejection force as well as in weight, length, and design. For example, the difference between the lightest instrument, the mLINE (Biohit Plc., Finland) (Figure 1), and the heaviest is more than 100 g (137 vs 241 g) (Table 1). Usually, the shorter and lighter the pipettor, the more ergonomic it is to use. However, more important than weight is the balance and fitting of the pipettor to the hand of the user. This is because good stability considerably reduces the strain on the muscles of the hand.1 Most, but not all, multichannel pipettors have a finger support to secure better fitting. Table 1 lists available mechanical multichannel pipettors and their features.
Ease of use
An important feature in multichannel pipettors is the ability to turn the liquid end to an optimal position, for exam