1999A&A...348..940D

We present the first attempt to determine the iron abundance in hot central stars of planetary nebulae. We perform an analysis with fully metal-line blanketed NLTE model atmospheres for a sample of ten stars (T_eff>70000K) for which high-resolution UV spectra are available from the IUE archive. In all cases lines of FeVI or FeVII can be identified. As a general trend, the iron abundance appears to be subsolar by 0.5-1dex, however, the S/N of the IUE spectra is not sufficient to exclude a solar abundance in any specific case. Improved spectroscopy by either FUSE or HST is necessary to verify the possibility of a general iron deficiency in central stars. The suspected deficiency may be the result of gravitational settling in the case of three high-gravity objects. For the other stars with low gravity and high luminosity dust fractionation during the previous AGB phase is a conceivable origin.