HPLC Accessories
HPLC- High Performance Liquid Chromatography (HPLC) is an analytical process utilizing special instruments designed to separate, quantify and analyze components of a chemical mixture. Samples of interest are introduced to a solvent flow path; carried through a column packed with specialized materials for component separation; and component data is obtained through the combination of a detection mechanism coupled with a data recording system. All this occurs under pressures which may reach or exceed 6,000 psi!
The basic components of an HPLC system include a solvent reservoir, pump, injector, analytical column, detector, recorder and waste reservoir. Other important elements are an inlet solvent filter, post-pump inline filter, sample filter, precolumn filter, guard column, back-pressure regulator and/or solvent sparging system. The function of each of these components is briefly described below.
An HPLC system begins with the solvent reservoir, which contains the solvent used to carry the sample through the system. The solvent should be filtered with an inlet solvent filter to remove any particles that could potentially damage the system's sensitive components.
Solvent is propelled through the system by the pump. This often includes internal pump seals, which slowly break down over time. As these seals break down and release particles into the flow path, an inline solvent filter prevents any post-pump component damage.
The next component in the system is the sample injector, also known as the injection valve. This valve, equipped with a sample loop of the appropriate size for the analysis being performed, allows for the reproducible introduction of sample into the flow path. Because the sample often contains particulate matter, it is important to utilize either a sample filter or a precolumn filter to prevent valve and column damage.
Following the injector, an analytical column allows the primary sample separation to occur. This is based on the differential attraction of the sample components for the solvent and the packing material within the column. However, a sacrificial guard column is often included just prior to the analytical column to chemically remove components of the sample that would otherwise foul the main column.
Following the analytical column, the separated components pass through a detector flow cell before they pass into the waste reservoir. The sample components' presence in the flow cell prompts an electrical response from the detector, which is digitized and sent to a recorder. The recorder helps analyze and interpret the data.
As a final system enhancement, a back pressure regulator is often installed immediately after the detector. This device prevents solvent bubble formation until the solvent is completely through the detector. This is important because bubbles in a flow cell can interfere with the detection of sample components. Alternatively, an inert gas sparging system may be installed to force dissolved gasses out of the solvent being stored in the solvent reservoir.