Inline Filters vs. Guard Columns for HPLC

Filters, such as inline filters, pre-column filters, and column guards, protect analytical columns from wear and premature failure within the HPLC system. The chromatographic separation of the HPLC column begins to decline over time due to the gradual accumulation of irreversibly bound compounds on the stationary phase and particulate buildup on the frit. For example, particulates from the mobile phase buffer, debris from pump seals shedding, and particulates from injected samples can accumulate at the column inlet and result in increased back pressure or a plugged column. Filters and guard columns alleviate these troubles by collecting damaging compounds before they reach the analytical column.  

Inline Filters vs. Guard Columns for HPLC  

Inline Solvent Filter  

An inline solvent filter has two purposes: to trap particles in the mobile phase to prevent damage to downstream components and to prevent damage to the rotor seal from pump seal shedding. Since it is placed between the pump and injector, minimizing void volume is not critical for inline solvent filters.  

Pre-Column Filters  

Pre-column filters are an inexpensive option to protect the HPLC column from debris and particulates. Particles and debris cause increased pressure on the column when buildup occurs. This is typically a union style connection, with an easily replaceable economic frit of specified porosity plumbed between the injector and the column. These filters can increase the life of the column by filtering out particles that can wear on the column over time.   

Since pre-column filters are placed after the injector and immediately before the column, it is important to minimize swept volume (internal volume due to the holder geometry and frit porosity). High-performance pre-column filters can be used at Ultra-High Pressures, have small pore sizes (down to 0.2 µm), and have minimal internal volumes to minimize peak broadening.   

Guard Columns  

A guard column is a protective column that is installed between the injector and the analytical column. Guard columns have two main functions. The first is to trap particulate matter that would otherwise block the column through a frit at the inlet. They also utilize packing material that is matched to the analytical column to trap materials that would become strongly or irreversibly bound to the analytical column.  

In a debate between inline filters vs. guard columns for HPLC, guard columns are a more expensive option than inline filters; however, they protect the column from the irreversible buildup of compounds on the analytical column. Inline filters, pre-column filters, and guard columns filter out components that can lead to system failure. Visit Chrom Tech for all your filtration, column protection, and other chromatography supplies.