ASTM D859-16(2021)e1
Standard Test Method for Silica in Water

Standard No.
ASTM D859-16(2021)e1
Release Date
2021
Published By
American Society for Testing and Materials (ASTM)
Latest
ASTM D859-16(2021)e1
Scope
1.1 This test method covers the determination of silica in water and waste water; however, the analyst should recognize that the precision and accuracy statements for reagent water solutions may not apply to waters of different matrices. 1.2 This test method is a colorimetric method that determines molybdate-reactive silica. It is applicable to most waters, but some waters may require filtration and dilution to remove interferences from color and turbidity. This test method is useful for concentrations as low as 20 µg/L. 1.3 This test method covers the photometric determination of molybdate-reactive silica in water. Due to the complexity of silica chemistry, the form of silica measured is defined by the analytical method as molybdate-reactive silica. Those forms of silica that are molybdate-reactive include dissolved simple silicates, monomeric silica and silicic acid, and an undetermined fraction of polymeric silica. 1.4 The useful range of this test method is from 20 to 1000 µg/L at the higher wavelength (815 nm) and 0.1 to 5 mg/L at the lower wavelength (640 nm). It is particularly applicable to treated industrial waters. It may be applied to natural waters and wastewaters following filtration or dilution, or both. For seawater or brines, this test method is applicable only if matched matrix standards or standard addition techniques are employed. 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. NOTE 1—For many natural waters, a measurement of molybdatereactive silica by this test method provides a close approximation of total silica, and, in practice, the colorimetric method is frequently substituted for other more time-consuming techniques. This is acceptable when, as frequently occurs, the molybdate-reactive silica is in the milligram per litre concentration range while the nonmolybdate-reactive silica, if present at all, is in the microgram per litre concentration range. 1.7 Former Test Method A (Gravimetric—Total Silica) was discontinued. Refer to Appendix X1 for historical information. 1.8 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.

ASTM D859-16(2021)e1 Referenced Document

  • ASTM D1066 Standard Practice for Sampling Steam
  • ASTM D1129 Standard Terminology Relating to Water
  • ASTM D1193 Standard Specification for Reagent Water
  • ASTM D2777 Standard Practice for Determination of Precision and Bias of Applicable Methods of Committee D-19 on Water
  • ASTM D3370 Standard Practices for Sampling Water from Closed Conduits
  • ASTM D4841 Standard Practice for Estimation of Holding Time for Water Samples Containing Organic and Inorganic Constituents
  • ASTM D5810 Standard Guide for Spiking into Aqueous Samples 
  • ASTM D5847 Standard Practice for Writing Quality Control Specifications for Standard Test Methods for Water Analysis
  • ASTM E275 Standard Practice for Describing and Measuring Performance of Ultraviolet, Visible, and Near-Infrared Spectrophotometers
  • ASTM E60 Standard Practice for Analysis of Metals, Ores, and Related Materials by Molecular Absorption Spectrometry

ASTM D859-16(2021)e1 history

Standard Test Method for Silica in Water


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