  We present an analysis of UV spectra of quasars at intermediate redshifts
believed to belong to the extreme Population A (xA), aimed to estimate the
chemical abundances of the broad line emitting gas. We follow the approach
described in a previous work extending the sample to 42 sources. Our aim is to
test the robustness of the analysis carried out previously, as well as to
confirm the two most intriguing results of this investigation: evidence of very
high solar metallicities, and deviation of the relative abundance of elements
with respect to solar values. The basis of our analysis is multi-component fits
in three regions of the spectra centered at 1900, 1550 and 1400 A in order to
deblend the broad components of AlIII1860, CIII]1909, CIV1549, HeII1640, and
SiIV1397+OIV]1402 and their blue excess. By comparing the observed flux ratios
of these components with the same ratios predicted by photoionization code
CLOUDY we found that the virialized gas (broad components) presents a
metallicity Z higher than 10Z$_\odot$. For non-virialized clouds we derive a
lower limit to the metallicity around $\sim$ 5Z$_\odot$ under the assumption of
chemical composition proportional to the solar one, confirming the previous
results. We especially rely on the ratios between metal lines and HeII1640.
This allowed us to confirm systematic differences in the solar-scaled
metallicity derived from the lines of Aluminium and Silicon, and of Carbon,
with the first being a factor 2 higher. For luminous quasars accreting at high
rates, high Z values are likely, but that Z scaled values are affected by the
possible pollution due to highly-enriched gas associated with the circumnuclear
star formation. The high-Z values suggest a complex process involving nuclear
and circumnuclear star formation, interaction between nuclear compact objects
and accretion disk, possibly with the formation of accretion-modified stars.
