Abstract
We compared elemental abundances of field and open cluster Ap Si stars. In particular, an analysis of the Ap Si stars HD 87240 and HD 96729 is presented using an ATLAS9 model atmosphere and observational material taken with a REOSC echelle spectrograph attached to the Jorge Sahade 2.15 m telescope at CASLEO. These chemically peculiar (CP) stars belong to the southern hemisphere open clusters NGC 3114 and NGC 3532, respectively. For HD 87240 and HD 96729, C is mostly solar, Mg and S are slightly underabundant, Si and Ca are overabundant by factors between 1--10. Heavier elements are all overabundant, TiCrFe by factors of ∼ 10, SrYZr by factors between 100--1000 and rare earths by factors of ∼ 1000 or more.
