Low pressure liquid chromatography (LPLC) systems force the mobile phase through the column at low pressure. LPLC was performed in open columns using gravity to “pump” the solvent through the column. This type of LPLC is known as ‘open column liquid chromatography’. Today, LPLC is typically performed with pump-driven instrumentation.

LPLC is a highly selective technique used mostly in the study of biomolecules, like proteins, peptides, and monoclonal antibodies. LPLC is primarily a preparative and non-destructive technique, making it ideal for the separation of biomolecules and purification of recombinant-tagged proteins. LPLC is also used to purify active pharmaceutical ingredients, remove pesticides from samples, and purify small molecules.

LPLC INSTRUMENTATION
LPLC is a system made of a column, low pressure pump (often peristaltic), injector, detector, and fraction collector. The simple peristaltic roller pump draws the mobile phase from the reservoir at a fixed flow rate and transfers the mobile phase to the column.

The solvent (mobile phase) then passes through an injector containing the sample to deliver the sample to the column for separation. Sample components are separated as they pass through the column and reach the detector at different rates. An in-line UV-Vis or refractive index (RI) detector monitors the column effluent, allowing samples to be collected using a fraction collector. Collected samples are organized by time of elution.

LPLC ADSORBENTS AND HARDWARE
The column matrix material should have good mechanical and chemical stability, they should contain functional groups to facilitate analyte attachment, and be inert. Column hardware materials are commonly made up of glass and inert plastic materials, depending on the solvent used.