Pipettes - pipette types, materials and areas of application

Pipettes are used to measure the volume of liquids, making them an irreplaceable laboratory tool. The various types of pipettes differ in terms of measuring accuracy, handling and areas of application. To help you choose the right pipette for your application, here are the features and differences between the most important pipette types.

Graduated Pipette / Measuring Pipette

The graduated pipette or measuring pipette is characterised by a volume scale that enables liquid volumes to be read. It is suitable for measuring and transferring different volumes of liquids and is available in different sizes, the most common being between 0 and 25 ml. Graduated pipettes are made of glass or plastic and have a conical tip. As the accuracy of the liquid volume reading depends on the user, a precise result is not guaranteed, especially with larger graduated pipettes.

Microliter Pipette

Microlitre pipettes, or micropipettes for short, are also known as piston-operated pipettes or Eppendorf pipettes. They are ideal for precise dosing of small volumes from 0.1 µl to 5000 µl. There are micropipettes with fixed and variable volumes, in which the desired number of microlitres can be set with the aid of an adjustment mechanism.

Micropipettes work according to the positive displacement principle. By means of a movable piston, the air column is displaced when it is pressed down and the liquid is sucked into the pipette when it is moved upwards. Only the attached pipette tip, made of plastic and disposable, comes into contact with the liquid to be pipetted.

Microliter pipettes are available as single-channel or multi-channel pipettes, whereby several liquid volumes of the same quantity can be aspirated or dispensed simultaneously. These are used for applications in laboratories where throughput is high and multiple reagents are transferred at once or extensive testing is performed.

Pasteur Pipette

The Pasteur pipette was named in honour of the French chemist and microbiologist Louis Pasteur. It has a long, narrow shape with a pointed opening at the end and is used to dispense liquids drop by drop, which is why it is also known as dropper or eye dropper. It does not have a measurement scale. In the laboratory, Pasteur pipettes are used for sampling and transferring various liquids such as alkalis, acids or chemicals. Dosage can be carried out very precisely using the suction bellows.

Pasteur pipettes are available in plastic or glass. Plastic pipettes are used for single-use applications such as urine, plasma or serum distribution. They are unbreakable and very light. Glass pasture pipettes have a high chemical resistance and can be used several times. Both types of pipette are sterile or non-sterile, depending on the intended use, and are available in different sizes.

Serological Pipette

Serological pipettes are mainly used in cell culture, microbiology and biochemistry for transferring and mixing chemical solutions and cell suspensions. Clinically, they are often used in the analysis of urine, for blood banking, immunology and haematology. Reagents of different densities can be easily dispensed using a pipette regulator or a piston. The pipette has an elongated, cylindrical shape and is graduated to allow different volumes of liquid to be measured.
Serological pipettes are usually made of sterile disposable polystyrene, but there are also pipettes made of glass. The glass pipettes can be sterilised and reused. The most common sizes are 10, 25 and 50 ml.

Transfer Pipette

A transfer pipette is a simple laboratory instrument for pipetting reagents, media or samples in cell culture or microbiology. As a disposable product, it is usually made of flexible plastic, is unbreakable and has a long, narrow shape with a wide opening at one end and a pointed tip at the other. The operation of a transfer pipette is based on the principle of aspirating and dispensing liquids. To aspirate liquid, the open end of the pipette is immersed in the liquid and by gently squeezing and releasing the upper part of the pipette, a vacuum is created which attracts or releases the liquid.

Transfer pipettes are available with and without graduation. They are particularly suitable for applications that require easy handling and moderate accuracy.

Volumetric pipette

A pipette that has only one mark for a specific volume is called a volumetric pipette. They measure and transfer a single, specific amount of liquid, but with very high accuracy. This makes volumetric pipettes ideal for applications in analytical or biochemistry that require a high degree of precision.

Volumetric pipettes are calibrated for ‘Ex’, dripping or gravity drainage. The volume of liquid printed on the pipette refers to the quantity to be dispensed. Volumetric pipettes are normally provided with a mark to ensure that the liquid drains completely. It is rarer to find volumetric pipettes with two marks for only partial drainage.

Volumetric pipettes are usually made of glass and cover common volumes of 0.5 to 100 ml or more.

Other pipettes

Weighing Pipette

Weighing pipettes are mainly used by dairy laboratories in conjunction with a balance. Liquids are aspirated with the pipette, the weight is tracked on the balance and gradually dispensed again.This allows the exact amount of substance dispensed to be determined. As the weight is decisive here, differences in the density of the liquid are irrelevant.

Suction Piston Pipette

Suction piston pipettes are volumetric pipettes and are fitted with an additional suction piston. In chemical laboratories, they are also known as safety pipettes. They are intended for simple and hazard-free pipetting, as corrosive, harmful and toxic liquids can be picked up and transferred.