Comment on "Long-range electrostatic interactions between like-charged colloids: Steric and confinement effects" - art. no. 013401

In a recent study [Phys. Rev. E 60, 6530 (1999)], Trizac and Raimbault show ed that the effective pair interaction between like-charged colloids immers ed in a cylindrically confined electrolyte remains repulsive even when the size of the microions and the finite longitudinal extension of the confinin g cylinder are taken into account. Contrary to their claim, we argue that t he case of finite longitudinal confinement does not always generate repulsi ve interactions and to illustrate this point we also provide a simple examp le.