Proper Use of Positive-Displacement Pipettes

Positive-displacement technology, like that used in our MICROMAN® E pipettes, is ideal when working with infectious, viscous, foaming, hot, cold, or volatile liquids because the disposable piston within the capillary piston (CP) tip is in direct contact with the sample. The CP technology thus removes any air cushion inside the pipette and ensures the volume accuracy is not affected by the fluid's properties. This also helps prevent contamination and protects both the user and the pipette.

In this article, we’ll highlight the proper use of positive-displacement pipettes and how you can get the best use out of your MICROMAN E.

Pipetting with MICROMAN E

The principle of the positive-displacement, and the absence of air cushion inside the pipette, enable a simple, quick, and reliable use of MICROMAN E.

As described in Figure 1, the complete pipetting technique consists in only four steps:

  1. Preparing the aspiration by simply pushing on the button until the first stop
  2. Aspirating
  3. Dispensing by simply pushing on the button until the first stop
  4. Ejecting the capillary piston tip by further pushing on the button until the second stop

Unlike air-displacement pipettes, MICROMAN E does not have any air cushion and there is no purge needed. Consequently, the Reverse Pipetting mode is not suitable with a positive-displacement pipette.

Figure 1. Proper Use of the MICROMAN E Positive-Displacement Pipette.
The MICROMAN E pipette is as easy to use as other PIPETMAN models.

Using your MICROMAN E with Capillary Piston Tips

Pipetting with a MICROMAN E is as easy as using an air-displacement pipette. The CP can be fit onto the pipette in only two steps thanks to the patented QuickSnap system (which reduces and secures the number of steps required to fit a CP). The process is summarized in Figure 2:

  1. Press the MICROMAN E into the CP until it is firmly secured and pick up the CP from the rack
  2. Slowly press the push button until there is a slight click and continue to press to the first stop

Greater uniformity and precision of dispensing are usually obtained by providing identical contact surfaces for all aliquots. This is achieved by pre-rinsing with the same liquid that is being dispensed.

To pre-rinse, aspirate with the CP and then dispense back into the original reservoir or to waste after the insertion of the CP.

Finally, you can easily eject the CP by pressing the push button until the second stop, and avoid any contact with the disposable CP.

Figure 2. Patented QuickSnap system for fitting CP on MICROMAN E.


In certain cases, the different kinds of fluids used with MICROMAN E, such as viscous fluids, could adhere to the outside of the CP tip wall. If liquid does adhere, wipe the outside of the CP tip with a clean wipe, without touching the orifice. It is important to choose a tissue that is resistant, lint-free, and inert to acids and solvents. As always, dispose of the tissue in a safe, hygienic manner.

MICROMAN E Positive-Displacement Pipettes

Interested in integrating positive-displacement pipettes in your lab?

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