A GC column may become contaminated over time by the accumulation of non-volatile material and may be damaged by the continuous condensation and evaporation of solvents and analytes. By using GC retention gaps, also known as precolumns, the lifetime of the GC columns can be extended cost-effectively. Retention gaps are mainly used for focusing the sample components when introducing large (liquid) sample quantities onto the column.
GC retention gaps consist of a length of uncoated, deactivated fused silica capillary tubing placed between the GC injection port and the GC column. The columns are connected by press-fit connectors. Altmann includes their own brand GC retention gaps for various applications, with different lengths and different inner diameters.