Silica oligomers and polymers may remain undetected unless they are decomposed into monomeric units. To achieve complete dissolution of all silica species, a strong acid digestion, such as hydrofluoric acid (HF), is recommended. It is important to note that HF is highly hazardous and necessitates meticulous handling procedures.

In cases where samples exhibit elevated concentrations of silica or sodium, it is advisable to dilute them to reduce potential interferences and to ensure that the response in Inductively Coupled Plasma (ICP) analysis remains within the linear range.

The blue molybdenum method is particularly effective for the quantification of reactive silica, specifically monomeric Si(OH)₄, and is extensively employed for silica analysis in aqueous and dilute solutions. This method entails the reaction of silica with molybdate, resulting in the formation of a yellow silicomolybdate complex, which is subsequently reduced to a blue complex for spectrophotometric assessment.

This technique demonstrates reduced susceptibility to sodium interference and is appropriate for samples containing low to moderate levels of silica. However, it may fail to identify polymeric or colloidal silica unless the sample undergoes pretreatment, such as heating or acid digestion, to convert all silica into its reactive form.