The Cogent TYPE-C™ Silica columns have certain specification ranges for pH that must be followed to avoid damage to the material. These specifications apply to the mobile phase eluent present in the column. 

The amount of sample injected is so small compared to the mobile phase eluent that the effect is not significant. Therefore you should be able to inject highly acidic samples without decreasing the column’s lifetime as long as the mobile phase is within column pH specifications. However, you may observe peak shape distortions if the mobile phase pH is much different than the sample pH. This does not mean the column was damaged but can happen any time the sample diluent and mobile phase pH differ significantly.