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

作者：Wu Jingfeng^*

来源：Marine Chemistry, 2007, 103(3-4): 370-381.

DOI：10.1016/j.marchem.2006.10.006

• seawater
• trace metal
• analysis
• iron

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 coprecipitation procedure to extract Fe from a 50 ml seawater sample into a 100 mu l 4% nitric acid (HNO3) solution followed by HR-ICPMS measurement. The high pre-concentration ratio (similar to 500:1) achieved by the procedure minimizes the Fe blank due to ICPMS instrumental Fe background and results in a detection limit of similar to 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.

• 出版日期2007-1-16