Standard No.:	GB/T 15057.6-1994
Chinese Name:	化工用石灰石中铁含量的测定 邻菲罗啉分光光度法
English Name:	Limestone for chemical industry- Determination of iron content- Phenanthroline 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 iron content by phenanthroline spectrophotometric method.

This standard is applicable to the determination of iron content in limestone products for chemical industry and the determination range (calculated by ferric oxide) is 0.05%~1%.

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

Melt the specimen with mixed flux of sodium carbonate - boric acid, leach with water and acidize it; after that, take ascorbic acid as reductant, adjust the pH value to about 4 with ammonium acetate, and ferrous iron reacts with phenanthroline and generates nacarat complex; then, measure the absorbance at spectrophotometer wavelength of 510nm.

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 Mixed flux: take two portions of anhydrous sodium carbonate (GB 639) and one portion of boric acid (GB 628), porphyrize them and mix well.

4.2 Hydrochloric acid (GB 622) solution: 1+1.

4.3 Ammonium acetate (GB 1292) solution: 200g/L.

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

4.5 Phenanthroline (GB 1293) solution: 1g/L; weigh 0.1g of phenanthroline and dissolve it into 10mL of ethanol (GB 679), add 90mL of water, and then mix well. This solution shall be preserved in a dark place; if color appears in the solution, the solution shall be reprepared.