Spectroscopic observations of 48 emission-line objects of M 33 have been obtained with the multi-object , wide field , fibre spectrograph AF2/WYFFOS at the 4.2m WHT telescope ( La Palma , Spain ) .
Line intensities and logarithmic extinction , c _ { \beta } , are presented for 42 objects .
Their location in the Sabbadin & D ’ Odorico diagnostic diagram ( H \alpha / [ S ii ] vs H \alpha / [ N ii ] ) suggests that > 70 \% of the candidates are Planetary Nebulae ( PNe ) .
Chemical abundances and nebular physical parameters have been derived for the three of the six PNe where the 4363Å [ O iii ] emission line was measurable .
These are disc PNe , located within a galactocentric distance of 4.1 kpc , and , to date , they are the farthest PNe with a direct chemical abundance determination .
No discrepancy in the Helium , Oxygen and Argon abundances has been found in comparison with corresponding abundances of PNe in our Galaxy .
Only a lower limit to the sulphur abundance has been obtained since we could not detect any [ S iii ] line .
N/H appears to be lower than the Galactic value ; some possible explanations for this under-abundance are discussed .