This standard specifies the determination method of iron content in bismuth. This standard is applicable to the determination of iron content in bismuth. Determination range: 0.0003%~0.0015%. GB/T 8220.2-1998 Chemical analysis method for bismuth 1,10-phenanthroline spectrophotometric method for determination of iron content GB/T8220.2-1998 Standard download decompression password: www.bzxz.net

GB/T8220.2-1998
This standard is a revision of GB8220.2-87 "Chemical analysis method for bismuth - determination of iron content by 1,10-diaza non-spectrophotometric method". In order to meet the requirements of GB/T915-1995 "Bismuth", the lower limit of determination of the method was extended from 0.0008% to 0.0003% during the revision. This standard complies with:
GB/T1.4-1988 Guidelines for standardization work Provisions for the preparation of chemical analysis method standards GB/T1467-1978 General principles and general provisions for chemical analysis method standards for metallurgical products GB/T7729-1987 General principles for spectrophotometric methods for chemical analysis of metallurgical products This standard is a supporting standard for GB/T915-1995 "Bismuth". The preparation method of this standard complies with the provisions of GB/T1.1~1993 (Guidelines for Standardization Work Unit 1: Rules for Drafting and Presentation of Subject Matter
Part 1: Basic Provisions for the Preparation of Standards). From the date of implementation, this standard will replace GB8220.2-87 and Appendix B of GB/T915~1995 "Bismuth". This standard was proposed by China Nonferrous Metals Industry Corporation. This standard is under the jurisdiction of the Standardization and Metrology Research Institute of China Nonferrous Metals Industry Corporation. The drafting units of this standard are Zhuzhou Smelter and Shanghai Smelter. The main drafters of this standard are Cai Jun and Zheng Huiqi. This standard was first issued in 1966, revised for the first time in October 1976, and revised for the second time in September 1987. 315
1 Scope
National Standard of the People's Republic of China
Methods for chemical analysis of bismuth
1,10-phenanthroline spectrophotometric method for determination of iron contentMethods for chemical analysis Bismuth-Determination of iron content-1, 10-Phenanthroline photometric method This standard specifies the determination method of iron content in bismuth. This standard is applicable to the determination of iron content in bismuth. Determination range: 0.0003% to 0.0015%. 2 Method Summary
GB/T 8220.2-- 1998
Replace G8220.287
The sample is dissolved in nitric acid at low temperature. In a near-neutral solution, the complex cation formed by iron (II) and 1,10-phenanthroline reacts with iodide ions to form an ion complex that can be extracted by chloroform. Its absorbance is measured at a wavelength of 510nm. Bismuth and other interfering elements can be masked by adding disodium ethylenediaminetetraacetic acid and citrate. 3 Reagents
The water used for preparing solutions and analysis is double distilled water. 3.1 Chloroform.
3.2 Anhydrous sodium sulfate.
3.3 Nitric acid (1+1), ultrapure.
3.4 ​​Nitric acid (3+500), ultrapure.
3.5 Ammonia water (1+1), ultrapure.
3.6 Disodium ethylenediaminetetraacetic acid solution ( 250g/L) 3.6.1 Weigh 125g of disodium ethylenediaminetetraacetate (CloHN,O.Na2·2H.O) in a 600mL beaker, add 300ml of water, drop ammonia water (p0.90g/mL) until it is completely dissolved and adjust to pH7. 3.6.2 Add 5mL of sodium perchlorate solution (neutralize 1mol/L perchloric acid solution with 1mol/L sodium hydroxide solution to neutrality), dilute to 500ml with water. Add 1g of hydroxylamine hydrochloride and 0.1g of 1,10-phenanthroline, stir until all dissolved, heat in a 50-60 water bath for 10min, take out, and cool. Transfer to a 1000mL separatory funnel and extract with dichloroethane (add 20-30ml of dichloroethane each time, shake for 1min), until the organic layer is colorless and then extract twice. Separate the organic layer, filter the aqueous phase with absorbent cotton, and store in a reagent bottle for later use. 3.7 Ammonium citrate solution (250g/L): Weigh 125g of ammonium citrate into a 600mL beaker, add 300ml of water to dissolve completely, and adjust to pH 7 with ammonia water (p0.90g/mL). Proceed as in 3.6.2. 3.8 Buffer solution (pH 7): Mix 250mL of acetic acid (1mol/L) and 250ml of ammonia water (1mol/1.), and proceed as in 3.6.2. 3.9 1,10-phenanthroline (CzHgN2·H20) solution (10g/L): Prepare with ethanol (1+1). 3.10 Hydroxylamine hydrochloride solution (100g/1): Weigh 50g of hydroxylamine hydrochloride into a 500mL beaker. Add 100ml of water to dissolve it: Adjust pH to about 7 with ammonia water (3.5). Add 20mL 1,10-phenanthroline solution (3.9), boil for 1-2 minutes, remove, cool, and transfer to a 500mL separatory funnel. Add 10mL chloroform each time and shake for 2 minutes until the organic layer is colorless. Discard the organic layer and dilute the aqueous phase to 500mL with water. 3.11 Potassium iodide solution (300g/L): Weigh 150g potassium iodide into a 600mL beaker, add 300mL water and 0.5g potassium aluminum sulfate. After all the solution is dissolved, add ammonia water (p0.90g/mL) dropwise until the precipitation is complete, then add 0.5mL in excess. Heat until the precipitation condenses, filter it with quantitative filter paper while it is hot into a 1000mL beaker. Add 10mL. Hydroxylamine hydrochloride solution (3.10), add water to 500ml, and store in a brown reagent bottle for later use.
3.12 Iron standard stock solution: weigh 0.1000g metallic iron (≥99.9%) into a 200mL beaker, add 20mL nitric acid (3.3), heat to dissolve it, remove nitrogen oxides, cool, transfer to a 1000mL volumetric flask, dilute to scale with nitric acid (3.4), and mix well. This solution contains 0.1 mg iron per ml.
3.13 Iron standard solution: Pipette 20.00 ml of iron standard stock solution (3.12) into a 500 ml volumetric flask, dilute to scale with nitric acid (3.4), and mix well. This solution contains 4 ug of iron in 1 ml. 4 Instruments
Spectrophotometer.
5 Analysis steps
5.1 Sample
Weigh 1.000 g of sample.
5.2 Blank test
Perform a blank test with the sample.
5.3 Determination
5.3.1 Place the sample (5.1) in a 100 ml beaker, add 5 ml of nitric acid (3.3), heat to dissolve, evaporate to 2~~3 ml, and remove. 5.3.2 Add 10 mL of disodium ethylenediaminetetraacetic acid solution (3.6) and 5 mL of ammonium citrate solution (3.7), and adjust the pH to about 7 with ammonia water (3.5). Add 5 mL of hydroxylamine hydrochloride solution (3.10) and 5 mL of 1,10-phenanthroline solution (3.9), heat in a 50-60°C water bath for 10 min, remove and cool.
5.3.3 Transfer to a 125 mL separatory funnel, add 10 mL of buffer solution (3.8), 10 mL of potassium iodide solution (3.11), and 5 mL of chloroform (3.1), and shake for 1 min. After standing and stratifying, place the organic phase in a 10 mL dry colorimetric tube, add 5 mL of chloroform (3.1) to the aqueous phase, and shake for 1 min. After standing and stratifying, combine the organic phases in a 10 mL dry colorimetric tube, dilute to the mark with chloroform (3.1), and mix well. Add a small amount of anhydrous sodium sulfate (3.2) and shake gently to remove moisture. 5.3.4 Place part of the organic phase (5.3.3) in a 2 cm absorption dish, use the blank sample as a reference, measure its absorbance at a wavelength of 510 nm on a spectrophotometer, and find the corresponding iron content from the working curve. 5.4 Drawing of the working curve
5.4.1 Take 0.50, 1.00, 2.00, 3.00, and 4.00 mL of the iron standard solution (3.13) and place them in a group of 100 ml beakers respectively. The following is carried out according to 5.3.2 to 5.3.3.
5.4.2 Place part of the organic phase in a 2 cm absorption dish, use the reagent blank as a reference, and measure its absorbance at a wavelength of 510 nm on a spectrophotometer. Draw a working curve with the iron content as the horizontal axis and the absorbance as the vertical axis. 6 Calculation and expression of analysis results
Calculate the percentage of iron according to the following formula:
Fe(%) == m, × 10-6
Wherein; mi\—the amount of iron found from the working curve ug; ma-the mass of the sample·g.
The analysis result should retain 2 significant figures.
Allowance
GB/T8220.2—1998
The difference in analysis results between laboratories should not be greater than the allowable difference in iron content listed in the following table
0.000 3~0.000 8
>0.000 80.001 5bzxz.net
Allowance
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