This standard specifies the determination of iron content by o-phenanthroline spectrophotometry. This standard is applicable to the determination of iron content in limestone products for chemical use, and the determination range (calculated as ferric oxide) is .0500\'1%0 GB/T 15057.6-1994 Determination of iron content in limestone for chemical use o-phenanthroline spectrophotometry GB/T15057.6-1994 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Determination of iron content in limestone for chemical industry
O-phenanthroline spectrophotometric method
Limestone for chemical industryDetermination of iron content-Phenanthroline spectrophotometric method1 Subject content and scope of application
This standard specifies the determination of iron content by o-phenanthroline spectrophotometric method. GB/T 15057.6—94
This standard is applicable to the determination of iron content in limestone products for chemical industry, and the determination range (calculated as ferric oxide) is 0.05% to 1%. 2 Reference standards
GB6682 Specifications and test methods for water used in analytical laboratories GB/T9721 General rules for molecular absorption spectrophotometry of chemical reagents (ultraviolet and visible light parts) 3 Summary of methods
The sample is melted with sodium carbonate-boric acid mixed flux, leached with water, acidified, ascorbic acid is used as a reducing agent, and ammonium acetate is used to adjust the pH to 4. Ferrous iron and o-phenanthroline generate an orange-red complex, and the absorbance is measured at a wavelength of 510nm on a spectrophotometer. 4 Reagents and solutions
The water used in this standard should meet the specifications of grade 3 water in GB6682. The listed reagents, unless otherwise specified, refer to analytical pure reagents. 4.1 Mixed flux: Take 2 parts of anhydrous sodium carbonate (GB639) and 1 part of boric acid (GB628), grind them finely, and mix them evenly. 4.2 Hydrochloric acid (GB622); 1+1 solution.
4.3 Ammonium acetate (GB1292): 200g/L solution. 4.4 Ascorbic acid: 20g/L solution (prepare before use). 4.5 Phenanthroline (GB1293): 1g/L solution. Weigh 0.1g of Phenanthroline and dissolve it in 10mL of ethanol (GB679), add 90mL of water and mix well. Store in a dark place. If the solution is colored during storage, re-prepare it. 4.6 Ferric oxide standard solution: 500μg/mL. Weigh 3.020g of ammonium ferric sulfate [NH,Fe(SO,)2·12H2O] (GB1279) and dissolve it in 200ml of water, add 20mL of sulfuric acid (GB625) 1+1 solution, transfer to a 1000mL volumetric flask, dilute to the mark, and shake well. This solution contains 500μg of ferric oxide in 1ml.
4.7 Ferric oxide standard solution: 50μg/mL. Pipette 50.00mL of ferric oxide standard bath solution (4.6), place in a 500mL volumetric flask, dilute to scale with water, and shake well. This solution contains 50μg of ferric oxide in 1mL. 5 Instruments
Spectrophotometer: It should comply with the provisions of GB/T9721. Approved by the State Bureau of Technical Supervision on May 5, 1994
Implementation on February 1, 1995
6 Test specimens
GB/T15057.6--94
Laboratory samples pass through a 125um test sieve (GB6003), dry at 105~~110℃ for more than 2h, and cool to room temperature in a desiccator.
7 Analysis steps
7.1 Weigh the sample according to the provisions of Table 1, accurate to 0.0001g, and place it in a platinum crucible. At the same time, do a blank test, Table 1bZxz.net
Fe2Oa content, %
0.05~0.40
>0. 40~1. 00
Weigh the sample amount, g
7.2 Add 2g of mixed flux (4.1), mix well, then cover with 1g of mixed flux, cover the crucible with a gap, place it in a high-temperature furnace, heat from low temperature to 950℃, keep for 10min, take it out, and cool it. Place the crucible in a 200mL beaker, add 40mL of hot water and 15mL of hydrochloric acid (4.2), heat at low temperature to overflow the molten material, and wash out the snail with water. Continue heating until the solution is clear, cool to room temperature, transfer to a 100mL volumetric flask, dilute to scale with water, and shake well. Pipette 25.00mL of the test solution into a 100mL volumetric flask, and add water to 50mL. 7.3 Add 5.0mL of ascorbic acid solution (4.4), shake well, and let stand for 5min. Add 5.0mL of ammonium acetate solution (4.3) and 10.0mL of o-phenanthroline solution (4.5), shake well, dilute to scale with water, and shake well. 7.4After 30min, use a 1cm absorption cell and measure the absorbance at a wavelength of 510nm on a spectrophotometer, using the blank test solution as a reference. 8 Drawing of working curve
Measure 0.00, 1.00, 2.00, 4.00, 6.00, 8.00mL of ferric oxide standard solution (4.7) and place them in a set of 100mL volumetric flasks, add 1.0mL of hydrochloric acid solution (4.2), and dilute to 50mL with water. The following steps are carried out according to 7.3 and 7.4, in which the reagent blank is used as a reference to measure the absorbance. Draw the working curve with the amount of ferric oxide as the horizontal axis and the corresponding absorbance as the vertical axis. 9 Expression of analysis results
The content of ferric oxide (FeO:) (α) expressed as mass percentage is calculated as follows: ×100=m×4×10-4
r=m,×10-6
-the amount of ferric oxide found from the working curve, μg, where; mi\-
10 allowable difference
the mass of the sample, name.
The arithmetic mean of the parallel analysis results is taken as the final analysis result. The absolute difference of the parallel analysis results should not be greater than the allowable difference listed in Table 2.
Content of ferric oxide (Fe2O3)
>0.15~0.50
>0.50~1.00
Positive loading
Allowance
Additional instructions:
GB/T 1 5057. 6--94
This standard is proposed by the Ministry of Chemical Industry of the People's Republic of China. This standard is under the jurisdiction of the Chemical Industry and Mining Design and Research Institute of the Ministry of Chemical Industry. This standard is drafted by the Chemical Industry and Mining Design and Research Institute of the Ministry of Chemical Industry. The main drafters of this standard are Xu Xiulan and Li Donghao. This standard refers to the Japanese Industrial Standard JISM8850-1982 "Limestone Analysis Method". Marking and granting
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