Standard No.:	GB/T 15057.9-1994
Chinese Name:	化工用石灰石中磷含量的测定 钼蓝分光光度法
English Name:	Limestone for chemical industry- Determination of phosphorus content- Molybdenum blue spectrophotometric method
Professional Classification:	D53 Building material raw material ore
Professional Classification:	GB National Standard
ICS Classification:	73.080
Issued by:
Issued on:	1994-05-05
Implemented on:	1995-02-01
Status:	VALID
Language:	English
File Format:	PDF
Word Count:	1500 words
Price(USD):	45 (USD)
Delivery:	via email in 1-3 business day

1 Subject Content and Application Scope

This standard specifies the determination of phosphorus content by molybdenum blue spectrophotometric method.

This standard is applicable to the determination of phosphorus content in limestone products for chemical industry and the determination range is 0.001%~0.2%.

2 Normative References

GB 6682 Water for Analytical Laboratory Use - Specification and Test Methods

GB/T 9721 Chemical Reagent - General Rules for the Molecular Absorption Spectrophotometry (Ultraviolet and Visible)

3 Method Summary

Decompose the specimen with nitric acid and perchloric acid; in hydrochloric acid medium, restore the generated phosphorus-molybdenum heteropoly acid into phosphomolybdenum blue; then, measure the absorbance at spectrophotometer wavelength of 680 or 780nm.

4 Reagents and Solutions

Water used in this standard shall conform to the specification of Grade 3 water specified in GB 6682; unless otherwise specified, the adopted reagents refer to analytical reagents.

4.1 Nitric acid (GB 626).

4.2 Perchloric acid (GB 623).

4.3 Hydrobromic acid (GB 621).

4.4 Hydrochloric acid (GB 622) solution: 1+2.

4.5 Hydrochloric acid solution: 1+6.

4.6 Sodium hydroxide (GB 629) solution: 200g/L.

4.7 Ammonium molybdate [(NH4)6Mo7O24?4H2O](GB 657) solution: 20g/L.

4.8 Ascorbic acid solution: 20g/L (prepared right before use).