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.
1 Subject Content and Application Scope
2 Normative References
3 Method Summary
4 Reagents and Solutions
5 Apparatus
6 Specimen
7 Analytical Procedures
8 Plotting of Working Curve
9 Expression of Analysis Results
10 Allowable Difference
Additional Information
