What makes a good guard column?
• Since the role of a guard column is to prevent fouling of the analytical column, the guard column should be considerably less expensive than the analytical column it protects. • To simplify method development the guard column should contain the same packing material as the analytical column. a. A larger particle size is acceptable as long as the packing material has the same chemical characteristics as the packing in the analytical column. b. The use of guard columns filled with large particle size pellicular packings used to be popular. Pellicular guard columns are relatively cheap and are effective in protecting the analytical column from particulate matter, but their low retentive capacity made them less suitable to protect the column from highly retentive sample components. • To minimize the backpressure in the system, the length of the guard column should be as short as possible, while being long enough not to cause breakthrough of strongly retained solutes to the analytical col
