Syringes

Syringes are instruments used to withdraw or expel materials such as liquids or gases. They can come in different shapes and sizes depending on their use, and are used in numerous fields of application: from cooking to medicine. Syringes are also used in chemistry laboratories, for example to add liquids in a confined space, a procedure for which great precision is required. They are also used to measure and transfer solvents and reagents when maximum measurement accuracy is not required.

Syringe shape and structure

A syringe consists of a piston inserted into a hollow cylindrical body. The piston can perform a forward or backward movement along the inner walls of the hollow body. This movement allows the syringe to draw in and expel a liquid through a port in the end of the body, into which a needle is inserted. There are also models in which the needle is replaced with other types of discharge, such as a tube. The needle has the task of directing the flow of liquid with maximum precision of direction and quantity, during its expulsion.
Generally, syringes have a capacity of between 1 and 100 ml, depending on their application. They are also graded along the hollow body, which is measured in millilitres. However, there are various models, which may differ in size and measurement.

Material

The first syringes were made of metal. Over time, however, other materials were used to ensure better performance. The most common material is plastic; polyethylene has good chemical resistance. However, the best performing material for syringes in the chemical field is borosilicate glass. This is preferred because of its characteristics that allow for maximum mechanical precision with regard to piston movement, as well as excellent thermal and chemical resistance. Plastic models are usually disposable and have a pre-injected needle, while glass models have an interchangeable needle.

Accessories

The use of syringes in the laboratory is accompanied by accessories. The needle is the most important accessory for models in which it can be replaced. There are different models of needles, for example sterile disposable needles with a plastic attachment. But there are also more sophisticated models with a Luer Lock attachment.
Another accessory used with syringes is the dispenser, which can be digital or manual. Dispensers are devices of very high precision and accuracy, with which the volume can be exactly selected and the piston stopped for reproducible dosing. They are therefore ideal for dispensing identical volumes.