This method is included in NEMI for informational purposes as it is approved by EPA for regulatory use. Detailed information on this method is not currently. eropoly acid. This is reduced to silicomolybdenum blue that is determined pho- tometrically. The method is analogous to APHA SiO2 D+E, ASTM D, . Find the most up-to-date version of ASTM D at Engineering

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Standard – Standard Test Method for Silica in Water ASTM D –

High blanks, nonlinear calibration curves, and poor reproducibility have been observed with some batches d8599 this compound.

Type II water was speci? 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.

Last previous edition approved in as D — It is the responsibility of the user of this xstm to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

ASTM D – 16 Standard Test Method for Silica in Water

Since the method includes an evaporation step, the applicable concentration range depends upon the volume of sample used in the determination. It is particularly applicable to treated industrial waters.

NOTE 1—For many natural waters, a measurement of molybdatereactive silica by this test method provides a close approximation of total silica, atm, in practice, the colorimetric method is frequently substituted for other more time-consuming techniques. Silica removal is commonly accomplished by ion exchange, distillation, reverse osmosis, or by astj, usually with magnesium compounds in a hot or cold lime softening process. Complex silicate residues that do not yield to this treatment are dissolved by alkali fusion and dehydrated with HCl.


Asrm to Appendix X1 for historical information. Historical Version s – view previous versions d8559 standard Translated Version adtm Silicon is the most abundant element in igneous rocks and is the characteristic element of all important rocks except the carbonates. It is the skeletal material of diatoms but is not known to play a signi? For seawater or brines, this test method is applicable only if matched matrix standards or standard addition techniques are employed. The CVS is a solution of the method analyte of known concentration mid-calibration range used to fortify reagent water.

Dehydration is completed by ignition, and the silica is volatilized as silicon tetra? NOTE 4—Batch to batch variations in ammonium molybdate aatm been found to affect results at low concentrations below 0.

Active view current version of standard Translated Standard: A blank should also be run with each sample batch maximum of 20 samples to check for sample or system contamination.

Current edition approved Feb. The LCS is a solution of method analytes of known concentration added to a matrix that sufficiently challenges the Test Method. Under the allowances made in v859. Measurements may be made at nm with a spectrophotometer, or to nm with a? A number in parentheses indicates the year of last reapproval. Calibration and Standardization It may be monomeric or polymeric. In solution it can exist as silicic acid or silicate ion, depending upon pH.

The analyte recoveries for the LCS should fall within the control limits of x 6 3S, where x is the IDP atm and S is the standard deviation of the mean recovery established from It may be applied to natural waters r859 wastewaters following filtration or dilution, or both. This can be compensated for by preparing standards in a matrix similar to that of samples or by using a standard additions technique.


Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend. Due to the complexity of silica chemistry, the form of silica measured is defined by the analytical method as molybdate-reactive silica. It is applicable to most waters, but some waters may require filtration and dilution to remove interferences from color and atm.

Shelf life of this reagent may be extended by refrigeration.

It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. When working with low concentrations of silica, a batch of ammonium molybdate known to asm reasonable blanks, linearity, and reproducibility should be set aside for this purpose.

ASTM D859 – 16

Individual reprints asm or multiple copies of this standard may be obtained by contacting ASTM at the above address or at phonefaxor service astm. Referenced Documents purchase separately The documents listed below are referenced within the subject standard but are not provided as part of the standard.

It is applicable to most waters, but some waters may require? Precision and Bias 5