Depletion in post-AGB stars with a dusty disc. II.

We present a chemical abundance analysis on the basis of high signal-to-noise and high resolution spectra for 12 stars of our newly defined sample. The selection criterion for the stars of this sample was their position in the RV Tauri box in the [12]-[25], [25]-[60] two-colour diagram. An additional requisite was the presence of a near-IR excess. We found that the photospheres of nine stars are affected by the depletion process. Since the most likely origin of the near-IR excess is a disc, this strongly suggests that the phenomenon of depletion and the presence of a disc are linked. Among the depleted stars we find different depletion patterns. In seven stars elements with a condensation temperature below 1500 K are not or only slightly affected. Large underabundances are measured only for most elements with a condensation temperature above 1500 K.