Abstract: The gradient effect of retention time on the gradient coated GCcolumn is investigated. The theoretical equation is derived. The columns possessing double exponential and exponential/linear gradient in k and l are treated from the viewpoint of gradient effect and the computer programme is given. An example of the use of gradient coated columns is described and the derived equation has been experimentally verified.

Key words: GC column, Gradient coated GC column, Column stuffing