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Ammonium ferric citrate has the formula (NH4)5Fe(C6H4O7)2. A distinguishing feature of this compound is that it is very soluble in water, in contrast to ferric citrate which is not very soluble.
A 2136 (OTTO) Ammonium ferric citrate, Green, GR Cas 1185-57-5 - used as an acidity regulator.