AU113: Determination of Dissolved Silica and Common Anions Using Dual Detection

Instrument Type: IC

Dissolved silica can be measured in solution as silicate using ion chromatography. While it cannot be determined by suppressed conductivity detection, silicate can be derivatized post-column with sodium molybdate reagent to form a complex that can be detected with high sensitivity at 410 nm. In this application, silicate and seven common anions, are separated using the IonPac AS22 column. After separation and detection by suppressed conductivity, the output from the suppressor is derivatized with molybdate reagent to detect silicate using visible absorbance.