A recent manuscript posted on astro-ph ( 0611578 ) by Fields et al .
( hereafter F06 ) reports evidence of supersolar metal abundances in Mrk 279 by analyzing its Chandra LETGS X-ray spectrum .
We point out that it is impossible in principle to obtain direct metal abundances from these X-ray data , since there is no handle on the amount of hydrogen column density .
If F06 would have lowered their C , N , O and Fe abundance by a factor of ten and increased the hydrogen column density by a factor of ten , they would have obtained an almost identical fit with subsolar metalicity .
F06 find support for their supersolar metal abundances from a cursory analysis of the UV data from the same Mrk 279 campaign .
We point out that F06 included in that analysis portions of the UV trough that are known to arise from gas unrelated to the outflow , which weakens the support from the UV data .
A detailed analysis of the Chandra LETGS X-ray spectrum was accepted for publication in A & A on Sept 14 2006 ( Costantini et al 2006 ; hereafter C06 ) and posted on astro-ph on the same date .
F06 ignore most of this published analysis while duplicating the finding of two ionization components with similar parameters to the ones found by C06 .
Finally , we note that it is possible to derive accurate abundances from the UV data set of this object .
We already published these findings in a conference precedings and have submitted the relevant manuscript to ApJ .
We find that relative to solar the abundances in the Mrk 279 outflow are ( linear scaling ) : carbon 2.2 \pm 0.7 , nitrogen 3.5 \pm 1.1 and oxygen 1.6 \pm 0.8 .