A pre-column is applied to the system to avoid the contamination of a separation column by protein etc. The lifetime of a separation column depends on a state of a pre-column. Generally speaking, a pre-column can be used for approximately 100 times injection of 10 μl with blood or tissue denatured protein samples or for months with mycrodialysis samples. These lifetime can change dramatically with the way of denaturing of protein as sample preparation or pre-column condition. To identify the quality of the precolumn, please replace the precolumn with a two way joint and run standard sample only with a separation column. If the peak shape becomes good, the main column is in a good condition. If your samples are microdialysis samples, please replace the precolumn gel and in let filter at least once for three month. You can also disassemble the precolumn and ensure the packing material is white in color  

For instructions on how to re-pack a precolumn, please see the attached Precolumn Packing Tool Kit manual or the following video.