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Fe-EDDHA and pH range of stable Iron chelate
After a long wait I finally got hold of Fe-EDDHA ( 6% Fe, min 95% chelated),
made by COMPO GmbH ( BASF Group ), Gilden Strasse 38, D-48157, Muenster,
The package has a graph showing the " pH range of stable iron chelated "
The vertical axis ( Y ) records " Iron Chelated % solution " from 0 - 1.0
The horizontal axis ( X ) records " stable pH range " from 4.6 - 14.0
The curve for Fe-EDTA begins at 1.0 on the Y-axis at a pH of about 5.6 and
drops down to zero on the Y-axis at a pH of 8.0
The curve for Fe-DTPA begins at 1.0 on the Y-axis at a pH of 8.0 and drops
down to zero on the Y-axis at a pH of 11.2.
The curve for Fe-EDDHA begins at 1.0 on the Y-axis at a pH of 10.3 and drops
down to zero on the Y-axis at a pH of 13.8.
The curve is more or less a straight line except at the upper and lower
extremities where it flattens out for about 0.2 - 0.3 units.
Does this mean the greater the concentration of a Fe-EDTA solution the more
unstable it is ?.
Have I been screwing up mixing a highly concentrated Fe-EDTA solution all
these years only to end up with the chelate breaking up ? Especially when I
add it to my aquarium water with a pH near 7.0 ?
Did the Acetic acid radical save me ?
I haven't been testing for Iron regularly so I really don't know.
Fe-EDDHA is available right here in India, in 1 kg packing and the cost is
not high. Also available is a micronutrient mixture with Fe, Mn, Zn & Cu
chelated with EDTA and includes Mo again in 1 kg packing. In case anyone is
interested e-mail me offlist for the source. Both are quickly and completely
soluble in water and leave no residue what so ever behind.