  Because of the large energy separation between O-K and Mo-L$_{2,3}$ edges,
extracting precise and reliable chemical information from core-loss EELS
analyze of molybdenum oxides has always been a challenge. In this regard
Mo-M$_{2,3}$ edges represents an interesting alternative as they are situated
close to the O-K edges. They should allow thus the extraction of a wealth of
chemical information from the same spectra. However the main difficulty to
overcome in order to work properly with these edges is the delayed maxima of
the Mo-M$_{4,5}$ edges which hinders the automated background subtraction with
the usual inverse power low function. In this study we propose another
background subtraction method specifically designed to overcome this obstacle
and we apply it to the study of MoO3 and MoO2. We are able to show that
quantitative chemical information can be precisely and accurately determined
from the joined analyze of O-K and Mo-M$_{2,3}$ edges. In particular k-factors
are derived as a function of the integration window width and standard errors
close to 2% are reported. The possibility to discriminate the two oxides thanks
to chemical shifts and energy-loss near-edge structures is also investigated
and discussed. Furthermore the M$_3$/M$_2$ ratios are derived and are found to
be strongly dependent on the local chemical environment. This result is
confirmed by multiplet calculations for which the crystal field parameters have
been determined by ab initio calculations. The whole methodology as well as the
conclusions presented in this paper should be easily transposable to any
transitions metal oxides of the 4d family. This work should open a new and
easier way regarding the quantitative EELS analyses of these compounds.
