  We have used spectra obtained as part of the Science Verification program of
the FLAMES multi-object spectrograph mounted on Kueyen (VLT-UT2) to perform an
abundance analysis of stars along the giant branch (RGB) in the globular
cluster NGC 2808. Sodium abundances are derived from Na D lines for a sample of
81 cluster stars spanning a range of about 2 magnitudes from the tip of the
RGB. Our results show that a large star-to-star scatter does exist at all
positions along the RGB, suggesting large variations in the abundance of proton
capture elements down to luminosities comparable to the red horizontal branch
(HB). The distribution of Na abundances along the RGB seems to point out that
in this cluster most of the observed spread has a primordial origin.
Overimposed evolutionary effects, if any, must be only at ``noise'' level, at
odds with results from a similar analysis in M 13 (Pilachowski et al. 1996).
This study is a first step towards ascertaining if a link exists between the
distribution of chemical anomalies in light elements along the RGB and the
global properties of globular clusters, in particular the HB morphology.
