ASTM D7126-15(2023)

1.1 This test method covers the on-line determination of soluble silica in water by colorimetric analysis using the molybdenum blue method, also known as the heteropoly blue method.

1.2 This test method is applicable for silica determination in water with silica concentrations within 0.5 ppb to 5000 ppb (μg/L).

1.3 This test method covers the determination of soluble silica SiO₂ (silicon dioxide) or silicates in water. Soluble silica compounds are considered molybdate reactive silica. This test method does not cover the determination of colloidal or polymeric silica, which is considered non-molybdate reactive silica.

1.4 This test method does not cover the laboratory or grab sample measurement of silica in water. Refer to Test Method D859.

1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.