  Elemental abundances in the solar corona are known to be different from those
observed in the solar photosphere. The ratio of coronal to photospheric
abundance shows a dependence on the first ionisation potential (FIP) of the
element. We estimate FIP bias from direct measurements of elemental abundances
from soft X-ray spectra using data from multiple space missions covering a
range of solar activity levels. This comprehensive analysis shows clear
evidence for a decrease in FIP bias around maximum intensity of the X-ray flare
with coronal abundances briefly tending to photospheric values and a slow
recovery as the flare decays. The departure from coronal abundances are larger
for the low FIP elements Ca, Fe and Si than for S which have a mid FIP value.
These changes in the degree of fractionation might provide inputs to model wave
propagation through the chromosphere during flares.
