Determination of picomolar iron in seawater by double Mg(OH)2 precipitation isotope dilution high-resolution ICPMS

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42 Scopus citations


A low-blank pre-concentration procedure is described for the analysis of picomolar iron (Fe) in seawater by isotope dilution high-resolution inductively coupled plasma mass-spectrometry (HR-ICPMS). The procedure uses a two-step Mg(OH)2 co-precipitation procedure to extract Fe from a 50 ml seawater sample into a 100 μl 4% nitric acid (HNO3) solution followed by HR-ICPMS measurement. The high pre-concentration ratio (∼ 500:1) achieved by the procedure minimizes the Fe blank due to ICPMS instrumental Fe background and results in a detection limit of ∼ 2 pM and a precision of ∼ 4% at the 50 pM Fe level. The measurement of a low-Fe seawater sample spiked with gravimetric Fe standard shows that the method can clearly distinguish 0.01 nM Fe from 0.02 nM Fe in seawater with high accuracy. The method is demonstrated by the analysis of dissolved Fe in the equatorial Pacific Ocean.

Original languageEnglish (US)
Pages (from-to)370-381
Number of pages12
JournalMarine Chemistry
Issue number3-4
StatePublished - Jan 16 2007
Externally publishedYes


  • Analysis
  • Iron
  • Seawater
  • Trace metal

ASJC Scopus subject areas

  • Oceanography
  • Chemistry(all)
  • Environmental Chemistry
  • Water Science and Technology


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