ONLINE DETERMINATION OF DISSOLVED SILICA IN SEAWATER BY ION-EXCLUSIONCHROMATOGRAPHY 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 couple d plasma mass spectrometry is described. This method was developed as a second, independent method to complement the usual colorimetric proc edure in the determination of a certified concentration of dissolved s ilica 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 li mit, conservatively estimated at 2.3 ng g(-1) as Si (0.08 mu M), is su perior to that achievable by direct analysis by inductively coupled pl asma atomic emission spectrometry.