Spectra quality impact on nebular abundances

The spectra are analysed in a homogeneous way to derive physical conditions and ionic and total abundances. The effects of recombination on the [OII] and [NII] emission lines are estimated by including the effective recombination coefficients in the statistical equilibrium equations that are solved for O^+^ and N^+^.

The results are shown to be significantly different than those derived using previous approaches. The O^+^ abundances derived with the blue and red lines of [OII] differ by up to a factor of 6, indicating that the relative intensities of lines widely separated in wavelength can be highly uncertain. In fact, the HeII lines in the range 4000-6800{AA} imply that most of the spectra are bluer than expected.