Abstract
We present results of model atmosphere analyses of two post-AGB stars, ZNG-1 in the globular cluster M10 and the halo star PG1704+222. A differential abundance analysis reveals typical post-AGB abundance patterns, both stars being generally metal poor with approximately solar He. Large C depletions, observed in all hot post-AGB objects, are confirmed. The C deficiency may suggest that hot post-AGB stars evolve off the AGB before the third dredge-up begins. However, Fe depletions observed in other similar stars suggest that gas-dust fractionation in the AGB progenitor is responsible for the observed composition of these objects.
