Specialty Pipettes

Pipettes can be classified based on the method they use to aspirate and dispense liquid samples. Positive displacement is one of those methods. Pipettes using positive displacement use a disposable piston and capillary system (also known as syringe tip) to make a physical void of the selected volume. The piston comes into direct contact with the sample, and when the piston is moved upward sample is drawn into the capillary.

A repeater pipette is an example of a pipette using a positive displacement method to dispense liquids. They are designed to draw in a large volume of liquid sample which is then dispensed in multiple, equal aliquots. They are available in electronic or manual versions and use disposable syringes in a wide range of volumes.

There are specific applications that require to transfer of macro volumes (i.e. V > 1 mL) but do not require high accuracy. Mixing cells in a flask, transfer nutrients, aliquot water from a glass bottle are some examples of these situations. Pipet controllers use disposables tips with volume ranging from 1 mL to 50 mL. These consumables can be made of plastic and or glass.

Pipette controllers can be manual or electronic devices that provide suction for glass or plastic serological pipettes. The main difference between a pipette and a pipette controller is user decides if the aspirated volume using a pipette controller is expected, while a pipette uses mechanical principles to aspirate/dispense a volume set by the user.

Some laboratory liquids by their nature (e.g., corrosives or toxic liquids) are best left in place in fume hoods or safety cabinets and not moved around the lab. A bottle-top dispenser is useful to transfer relatively small quantities of these liquids safely. The dispenser operates by pump action, and newer versions provide accurate and safe delivery of hazardous liquids in volumes up to 50mL.