In this paper we present the results of observations of seventeen H ii regions in thirteen galaxies from the SIGRID sample of isolated gas rich irregular dwarf galaxies .
The spectra of all but one of the galaxies exhibit the auroral [ O iii ] 4363Å line , from which we calculate the electron temperature , T _ { e } , and gas-phase oxygen abundance .
Five of the objects are blue compact dwarf ( BCD ) galaxies , of which four have not previously been analysed spectroscopically .
We include one unusual galaxy which exhibits no evidence of the [ N ii ] \lambda \lambda 6548,6584Å lines , suggesting a particularly low metallicity ( < Z _ { \odot } /30 ) .
We compare the electron temperature based abundances with those derived using eight of the new strong line diagnostics presented by ( 11 ) .
Using a method derived from first principles for calculating total oxygen abundance , we show that the discrepancy between the T _ { e } -based and strong line gas-phase abundances have now been reduced to within \sim 0.07 dex .
The chemical abundances are consistent with what is expected from the luminosity–metallicity relation .
We derive estimates of the electron densities and find them to be between \sim 5 and \sim 100 cm ^ { -3 } .
We find no evidence for a nitrogen plateau for objects in this sample with metallicities 0.5 > Z _ { \odot } > 0.15 .