Methodologies for amorphous silica analysis

Different methodologies have been investigated for their ability to extract amorphous silica (ASi) from soils and plant phytoliths. Methodologies typically used in soil science, including oxalate, acetate and citric extractions, were used in addition to an alkaline digestion technique commonly used in the aquatic sciences. Initial results show that the alkaline technique extracts nearly an order of magnitude greater amount of ASi. The alkaline extraction technique was tested on soil samples with and without acid and peroxide pre-cleaning. Samples, which were not pre-cleaned, showed a poor extraction efficiency of amorphous silica and poor reproducibility, while cleaned soil samples gave better reproducibility and an increase in the amount of Si extracted. (c) 2005 Elsevier B.V. All rights reserved.