When you use a 0.2 µm filter you remove any particle that is larger than 0.2 µm. 

This includes bacteria as well as many viruses and spores. However, it is important to note that when you remove these interferences, and your sample passes through the membrane and enters the outlet of the filter device, your solution is not really sterile any longer, unless you have sterilized the device.

Using the 0.2um filter is especially helpful for UHPLC methods as it is important to remove larger particles including bacterial that can clog the column frits which use very small pores.

Click HERE for ordering information and pictures of AQ brand of syringe filters.