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Direct Determination of Dissolved Phosphate and Silicate in Seawater by Ion Exclusion Chromatography Sector Field Inductively Coupled Plasma Mass Spectrometry

Author:
Yang, Lu, Pagliano, Enea, Mester, Zoltán
Source:
Analytical chemistry 2014 v.86 no.6 pp. 3222-3226
ISSN:
1520-6882
Subject:
atomic absorption spectrometry, detection limit, gel chromatography, isotope dilution technique, isotopes, phosphates, rapid methods, seawater, silicon
Abstract:
A method is described for the direct determination of dissolved phosphate and silicate in seawater using ion exclusion chromatography (IEC) coupled with sector field inductively coupled plasma mass spectrometry (SF-ICPMS). Dissolved silicate was determined by double isotope dilution using a ²⁹Si spike, whereas one point gravimetric standard addition with internal standard of the same ²⁹Si spike was employed to quantitate dissolved phosphate. Medium resolution was used for all measurements in order to resolve polyatomic interferences on Si and P isotopes. Concentrations of 1.670 ± 0.008 and 30.20 ± 0.09 μM (SD, n = 6) with precisions of 0.47 and 0.31% for the dissolved phosphate and silicate, respectively, were obtained in National Research Council Canada certified reference material MOOS-3 seawater, in good agreement with certified values of 1.60 ± 0.15 and 30.5 ± 0.8 μM (U, k = 2), respectively. The reported method is a rapid (10 min per run), simple, and accurate online technique that requires no sample pretreatment. Moreover, this procedure achieves <0.5% precision (at above analyte concentrations) and method detection limits of 0.006 and 0.004 μM (0.18 as P and 0.11 ng g–¹ as Si), respectively, using a of 100 μL injection of seawater. The proposed technique is robust and well-suited for the determination of dissolved phosphate and silicate in seawater.
Agid:
5299302