1996A&A...305..551A

On the base of photographic, Reticon and CCD spectra analysis we have derived the abundances for 8 s-Cepheids and V1162 Aql (before classified as s-Cepheid). The following results have been obtained: 1) all Cepheids (excluding only EU Tau) have solar-like abundances of α- and iron-group elements, 2) Na is overabundant for all program stars, 3) the carbon deficiency found for EU Tau, DT Cyg, V440 Per and nitrogen overabundance (DT Cyg), show that these s-Cepheids are not crossing the instability strip for first time, 4) s-process elements are slightly enhanced in the program stars, 5) V1162 Aql does not show any changes in C and N abundances. The most plausible explanation is that this star is a normal Cepheid (Cδ), but it is firstly crossing the instability strip toward the giant branch. This conclusion is also confirmed by its position on the evolutionary diagram.