Standards from 0 to 2.5 mg/L
Fe2+ were prepared from a 1 g Fe2+/L iron(II)-sulphate stock
solution (Merck, 99.5%). The concentration of Fe2+ was determined
by mixing 2.6mL of sample to 0.8mL of 0.05Morthophenantroline
chlorhydrate (Prolabo, 99.5%) and 2.5mL
of 5M acetic acid (Prolabo, 100%) in a 25 mL-flask, filled
with de-ionised water. Total iron concentration was determined
according to the same protocol, but 2.6mL of 1M
ascorbic acid (Aldrich, 99%) was also added.