On-Line Determination of Dissolved Silica in Seawater by Ion Exclusion Chromatography in Combination with Inductively Coupled Plasma Mass Spectrometry

A method for the direct determination of dissolved silica in seawater by ion exclusion chromatography in combination with inductively coupled plasma mass spectrometry is described. This method was developed as a second, independent method to complement the usual colorimetric procedure in the determination of a certified concentration of dissolved silica in a planned seawater reference material. Ion exclusion affords a separation of the dissolved silica not only from the major seawater cations but also from potentially interfering anions. The detection limit, conservatively estimated at 2.3 ng g - 1 as Si (0.08 μM), is superior to that achievable by direct analysis by inductively coupled plasma atomic emission spectrometry.