Multi‐Element Determination of Trace Elements in Natural Water Reference Materials by ICP‐SFMS after Tm Addition and Iron Co‐precipitation

We report on an improved method for determining trace element abundances in seawater and other natural waters. The analytical procedure involves co‐precipitation on iron hydroxides after addition of a Tm spike, and measurement by inductively coupled plasma‐sector field mass spectrometry (ICP‐SFMS). The validity of the method was assessed through a series of co‐precipitation experiments, using ultra‐diluted solutions of a certified rock reference material (BIR‐1). Results obtained for four natural water reference materials (NASS‐5, CASS‐4, SLEW‐3, SLRS‐4) are in agreement with published working values for rare earth elements, yttrium, vanadium and, when available, for hafnium, zirconium, thorium and scandium. A set of proposed values with uncertainties typically better than 8% RSD is proposed for Hf, Zr and Th.