GB/T 223.61-1988 Methods for chemical analysis of iron, steel and alloy; The ammonium phosphomolybdate volumetric method for the determination of phosphorus content (English Version)
Dissolve the sample with oxidizing acid; at nitric acid acidity of 2.2mol/L, add ammonium molybdate to generate ammonium phosphomolybdate deposition; after filtering, dissolve with excessive standard sodium hydrate solution; taking dihydroxyphthalophenone solution as indicator, back-titrate the excessive sodium hydrate with dihydroxyphthalophenone solution till the pink just disappears (the end point) (about pH8).
The general reaction formula of dissolving ammonium molybdate precipitation with sodium hydrate is as:
Arsenic of less than 100μg, tantalum <500μg, zirconium, vanadium or niobium <1mg, wolfram <8mg, titanium < 10mg and silicon < 20mg contained in the test solution, may not interfere the determination; exceeding the limits above, remove arsenic by hydrochloric acid and hydrobromic acid; mask zirconium, niobium, tantalum, titanium and silicon by fluohydric acid; reduce vanadium by hydroxylamine hydrochloride; remove wolfram (in ammonia solution at presence of EDTA) by beryllium carrier.
GB/T 223.61-1988 Methods for chemical analysis of iron, steel and alloy; The ammonium phosphomolybdate volumetric method for the determination of phosphorus content (English Version)
Standard No.
GB/T 223.61-1988
Status
valid
Language
English
File Format
PDF
Word Count
2500 words
Price(USD)
60.0
Implemented on
1989-2-1
Delivery
via email in 1 business day
Detail of GB/T 223.61-1988
Standard No.
GB/T 223.61-1988
English Name
Methods for chemical analysis of iron, steel and alloy; The ammonium phosphomolybdate volumetric method for the determination of phosphorus content
1 Principle
Dissolve the sample with oxidizing acid; at nitric acid acidity of 2.2mol/L, add ammonium molybdate to generate ammonium phosphomolybdate deposition; after filtering, dissolve with excessive standard sodium hydrate solution; taking dihydroxyphthalophenone solution as indicator, back-titrate the excessive sodium hydrate with dihydroxyphthalophenone solution till the pink just disappears (the end point) (about pH8).
The general reaction formula of dissolving ammonium molybdate precipitation with sodium hydrate is as:
(NH4)2H(PMo12O40)•H2O+240H-=HPO +12MoO +2NH +13H2O
Arsenic of less than 100μg, tantalum <500μg, zirconium, vanadium or niobium <1mg, wolfram <8mg, titanium < 10mg and silicon < 20mg contained in the test solution, may not interfere the determination; exceeding the limits above, remove arsenic by hydrochloric acid and hydrobromic acid; mask zirconium, niobium, tantalum, titanium and silicon by fluohydric acid; reduce vanadium by hydroxylamine hydrochloride; remove wolfram (in ammonia solution at presence of EDTA) by beryllium carrier.
2 Reagents
