2.3. Preparation of Fe(III)–citrate solution
Fe(III)–citrate solution was prepared by adding FeCl3 to 30 mM
of Hepes buffer containing 100 mM citrate. Then the pH value of
the resulting solution was adjusted to 7.40 with NaOH. Resultant
Fe(III) solution was diluted with the above Hepes buffer to
10.0 mM. It is quite important to keep the ferric ion-to-citrate ratio
as 1:10, in which there is only Fe—๐citrate
3_
2 occurring in the citrate
system (Wang et al., 2008).