Iron is an essential element in living systems and is a limiting
nutrient for primary productivity in large regions of the World
Ocean [1]. To improve our understanding of the role of iron in global
biogeochemical cycles, it is necessary to gain high resolution data
and make consistent and accurate measurements of dissolved iron
species in natural waters. A range of analytical methods for the
determination of sub-nanomolar concentrations of dissolved iron
(hereafter referred to as DFe (Fe(II) + Fe(III))) in seawater have been
developed [2]. To allow the comparison of data between laboratories
that often use different analytical methods, common protocols
are normally adopted for the treatment of seawater samples, such
as careful handling under filtered air, filtration (