GB/T 6913-2008 Analysis of water used in boiler and cooling system - Determination of phosphorus
1 Scope
This standard specifies the method for determination of respective content of orthophosphates, total inorganic phosphates and total phosphates in water used in boiler and cooling system.
This standard is applicable to determining the respective content of orthophosphates, total inorganic phosphates and total phosphates (expressed as ) in water used in boiler and cooling system in the range of 0.05mg/L~50mg/L.
2 Normative references
The following standard contains provisions which, through reference in this text, constitute provisions of this standard. For dated references, subsequent amendments (excluding corrections) to, or revisions of, any of these publications do not apply to this standard. However, parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the referenced document applies.
GB/T 603 Chemical reagent - Preparations of reagent solutions for use in test methods (GB/T 603-2002, ISO 6353-1:1982, NEQ)
GB/T 6682 Water for analytical laboratory use - Specification and test methods (GB/T 6682-1992, neq ISO 3696:1987)
3 Determination of orthophosphate content
3.1 Principle
Allow the orthophosphates to react with ammonium molybdate solution in acidic solution, producing a yellow phosphorus molybdenum antimony complex. Subsequently, reduce this complex back to phosphomolybdenum blue using ascorbic acid, and determine its content using the spectrophotometric method at the maximum absorption wavelength of 710nm.
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The reaction formula is:
3.2 Reagents and materials
Unless otherwise specified, only analytical reagents and Grade 3 water specified in GB/T 6682 shall be used in this standard.
The preparations and products required in the test shall be prepared according to GB/T 603 unless otherwise specified.
Safety tips: The strong acid or alkali used in this standard is corrosive, so care shall be taken when using them. When splashed on a human body, it shall be rinsed with plenty of water to avoid its inhalation or contact with skin.
Foreword II
1 Scope
2 Normative references
3 Determination of orthophosphate content
4 Determination of content of total inorganic phosphates
5 Determination of content of total phosphates
Annex A (Informative) Specifications for detection dose range
Annex B (Informative) Interference test
Annex C (Informative) Matters to be borne in mind during analysis
