This Waters Model 300 Gel Permeation Chromatograph was developed in 1967/1968 by the American Waters Associates company (now Waters Corporation).

This instrument is about one and a half metres tall, 40cm wide and 40cm long and is made of a cream/beige metal casing. The front of the instrument has several boxes, the left hand one being locked and containing the power controls, and the right box having pressure gauge controls and with wires that could connect the chromatograph to other machines.

A separate section of the chromatograph contains a large assortment of spare tools and materials for operating, calibrating and maintaining the object.

Chromatography is technique of separating and potentially analysing chemical mixtures, and roughly means ‘writing colour’ stemming from the technique’s origins in the 19th century textile industry, where it was first used to separate pigments from mixtures. Today chromatography is used in the chemical, pharmaceutical, water, pesticide and oil industries, and the technique is used as both as a means of purification of chemicals by separating contaminants and as a method of analysing the properties of complex chemical compounds, such as their molecular weight or mass.

Whilst various methods of chromatography have been developed, the process generally involves placing a chemical mixture onto a solid surface component (called the stationary phase) and then dissolving through a liquid or gas component which and then made to move via rotation or gravity (mobile phase). The various components in the chemical mixture (called analytes when being studied) then separate from each other based on the different speeds in which they travel through the liquid or gas they have been mixed with.

This Waters Model 300 Gel Permeation Chromatograph was developed in 1967/1968 by Waters Associates which employs gel-permeation chromatography (GPC) to separate chemical mixtures. GPC was developed in 1963 and differs from other methods of chromatography in that it separates chemical components based on the differing sizes of the various component molecules (rather than based on the differing interactions and bonds of the molecules). Because of this GPC has become especially useful in the separation and analysis of organic polymers such as those produced from petroleum like polyethylene, PVC, polypropylene, polystyrene, polyester, nylon and acrylic. GPC can also be used to determine the different masses of the various molecular components in complex polymers. One of the important limitations of GPC is that it requires the component molecules to have at least a 10% difference in mass to be analysable.

The Waters Model 300 Gel Permeation Chromatograph was installed at the National Physical Laboratory in Teddington, who are responsible for standardising and regulating the measurements of units in the UK, including of the purity and composition of chemical compounds. This chromatograph was used to prepare standards of molecular weights for various types of petroleum-based plastics.