Effect of thawing condition on the recovery of reactive silicic acid from frozen natural water samples

A method for thawing frozen samples for silicic acid analysis is recommended. The maximum recovery of silicic acid is achieved by thawing the frozen samples in a refrigerator (at 4°C) in the dark for at least four days. This method significantly improves the recovery of silicic acid from frozen fresh water samples. It also permits close to 100% recovery of reactive silicic acid from frozen seawater samples even after three months storage.