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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Referenced Documents purchase separately The documents listed below are referenced within the subject standard but are not qstm as part of the standard. Ideally, the IPD solution should be prepared by an independent source from reference materials.

Standard Test Method for Silica in Water

When working with low concentrations of silica, a batch of ammonium molybdate known to produce reasonable blanks, linearity, and reproducibility should be set aside for this purpose. Individual reprints single or multiple copies of this standard may be obtained by contacting ASTM at the above address or at phonefaxor service astm.

It is the skeletal material of diatoms but is not known to play a signi? Under certain conditions, silica forms troublesome silica and silicate scales, particularly on highpressure steam turbine blades. Since the method includes an evaporation step, the applicable concentration range depends upon the volume of sample used in the determination. It may be applied to natural waters and wastewaters following?

Note 1—For many natural waters, a measurement of molybdate-reactive 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.

In cooling water systems, silica forms deposits when solubility limits are exceeded. It is applicable to aatm waters, but some waters may require?

After dissolving, add the solution to mL of a solution containing 30 g of sodium hydrogen sul? It is particularly applicable to treated industrial waters. For seawater or brines, this test method is applicable only if matched matrix standards or standard addition asstm are employed.


The collecting apparatus and storage containers for the reagent water must be polyethylene or other suitable plastic. The concentration of the IRM should be within the scope of the method, as de? Discard when the color darkens or a precipitate forms. This test method is useful for concentrations as low as 20? The CVS is a solution of the method analyte of known concentration mid-calibration range used to fortify reagent water.

This standard has been approved for use by agencies of the Department of Defense. The upper limit for acceptable precision and the range of acceptable recoveries are detailed below: 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.

Prepare a blank using a The IDP solution contains method analytes of known concentration, prepared from a different source to the calibration standards, used to fortify reagent water. Mix well and allow to stand for 10 min. No other units of measurement are included in this standard. Refer to Appendix X1 for historical information.

Due to the complexity of silica chemistry, the form of silica measured is de? Silicon is the most abundant element in igneous rocks and is the characteristic element of all aastm rocks except the carbonates. Dehydration is completed atsm ignition, and the 8d59 is volatilized as silicon tetra? Quality Control QC Historical Version s – view previous versions of standard. It is applicable to ashm waters, but some waters may require filtration and dilution to remove interferences from color and turbidity.

It is particularly applicable to treated industrial waters. The LCS is a solution of method analytes of known concentration added to a matrix that sufficiently challenges the Test Method.

It is particularly adtm to treated industrial waters. Reagents and Sstm NOTE 3—Store all reagents to be used in this test method in polyethylene or other suitable plastic bottles. In solution it can exist as silicic acid or silicate ion, depending upon pH. 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.

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It is found as the oxide in crystalline forms, as in quartz; combined with other oxides and metals in a variety of silicates; and in amorphous forms. For seawater or brines, this test method is applicable only if matched matrix standards or standard addition techniques are employed.

For measurements made at nm, silica concentration may be read directly in milligrams SiO2 per litre from the calibration curve prepared in Link to Active This link will always route to the current Active version of the standard.

ASTM D 水中硅测定的标准方法_百度文库

Silicon is the most abundant element in igneous rocks and is the characteristic element of all important rocks except the carbonates. Precision and Bias 5 It may be applied to natural waters and wastewaters following filtration or dilution, or both. Analyte Silica MS Amount ? Under the allowances made in 1. The MS should be prepared in accordance with Guide D Measurements may be made at nm with a spectrophotometer, or to nm with a?

Summary of Test Method 4. Those forms of silica that are molybdate-reactive include dissolved simple silicates, monomeric silica and silicic acid, and an undetermined fraction of polymeric silica.

Each operator made six determinations at each level, for a total of 72 determinations at each level. The lower limit of this method is 5 mg of silica. Check the concentration of this solution gravimetrically. Calibration and Standardization Originally approved in

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