chelated iron

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i was going to try to answer rex's question on dissolving chelated iron for
dosing when i realized i had a couple questions of my own.  I haven't been
able to find a molecular weight for Iron EDTA. how many iron's are chelated
per EDTA? supposedly iron edta is Iron(III) so i would guess one iron and an
extra sodium? which brings me to my next question - how is dry chelated iron
made? Iron sulfate mixed with disodium EDTA? is the Na2SO4 purified away
generally?
anyone?
TIA
elie