HPLC Guard Cartridges and Extra-Column ‘Dead’ Volume

The benefit of using a guard column with dirty samples is clear. By adding a short sacrificial column before the analytical column, column life increases due to trapping of particulates and strongly-retained compounds. However, adding the guard cartridge does increase the extra-column volume of our flow path. And, extra volume leads to lower efficiency and broader peaks, right? Not necessarily! Using a well-packed guard cartridge and very low volume connections, efficiencies can actually increase for the guard/analytical column pair vs. the column alone. For example, the Trident integrated guard uses a unique design that seats the guard cartridge right next to the analytical column. The efficiency, or number of theoretical plates, can actually increase with this design! The figure shows the change in efficiency using several styles and brands of guard systems. Using a guard cartridge can not only protect your column from contaminants, but also improve your separation.