GB 4333.4-1988 Chemical analysis methods for ferrosilicon - The chrome azurol S photometric method for the determination of aluminum content
Some standard content:
National Standard of the People's Republic of China
Methods for chemical analysis of ferrosiliconThe chromazurol S photometric method forthe determination of aluminium contentSubject content and scope of application
This standard specifies the determination of aluminium content by the chromazurol S photometric methodThis standard is applicable to the determination of aluminium content in ferrosilicon. Determination range: 0.100% to 0.600%. 2 Summary of method
UDC 669. 15'782
+543.421546
GB 4333.4—88
Replaces GB4333.4-84
The sample is dissolved in nitric acid and hydrofluoric acid, and perchloric acid is fuming. Then, in hydrochloric acid (1+11), the copper-iron reagent is used to precipitate iron, vanadium, titanium and other elements. Then in a hydrochloric acid solution of pH 5.8 ± 0.4, using hexamethylenetetramine as a buffer solution, aluminum and chrome azuro blue S form a purple-red complex, and its absorbance is measured at a wavelength of 550nm on a spectrophotometer. 3 Reagents
Sodium bisulfate, high-grade purity.
Hydrofluoric acid (pl.15g/mL), high-grade purity. 3.2
3.3 Perchloric acid (pl.67g/mL), high-grade purity. Nitric acid (pl.42 g/mL).
Hydrochloric acid (pl.19g/mL).
Hydrochloric acid (1+9).
Hydrochloric acid (1→+20).
Hydrochloric acid (1+60).
Hydrochloric acid (1+99).
Ammonium hydroxide, ultrapure (1+9).
Hexamethylenetetramine solution (200mg/mL). 3.12
Ammonium fluoride solution (20 mg/mL), in a plastic bottle. Ascorbic acid solution (10 mg/mL), prepare when needed. Copper iron reagent solution (60 mg/mL), prepare when needed. 3.14
2,4-dinitrophenol solution (2 mg/mL).
Chrome azurol S ethanol solution (0.4 mg/mL). Prepare with ethanol (1+1). Aluminum standard solution:
3.17.1 Weigh 0.1000g pure aluminum (more than 99.99%), place in a 200mL plastic beaker, add 10mL sodium hydroxide (super pure) solution (100 mg/mL) to dissolve the aluminum. Then neutralize with hydrochloric acid (1+1) until a precipitate is precipitated. Then add hydrochloric acid (1+1) dropwise until the precipitate is dissolved and then add 20 mL in excess. After cooling, transfer to a 1000 mL volumetric flask, dilute to scale with water, and mix. This solution contains 100 μg aluminum in 1 mL. 3.17.2 Take 10.00 mL of aluminum standard solution (3.17.1), place it in a 500 mL volumetric flask, add 5 mL of hydrochloric acid (1+1), dilute to scale with water, and mix. This solution contains 2 ug aluminum in 1 mL. 4 Sample
The sample should pass through a 0.125mm sievewwW.bzxz.Net
5 Analysis steps
5.1 Safety measures
When using perchloric acid to generate smoke, avoid contact with organic matter and ammonia. When destroying the copper-iron reagent, it should be treated with nitric acid first, and then perchloric acid should be added.
5.2 Sample quantity
Weigh 0.1000g of sample.
5.3 Blank test
Perform a blank test with the sample.
5.4 Determination
5.4.1 Place the sample (5.2) in platinum blood, add 5mL nitric acid (3.4), slowly drop 3-5mL hydrofluoric acid (3.2), place on a low-temperature electric furnace and heat until the sample is dissolved. Add 2mL perchloric acid (3.3), heat until smoked, remove and cool slightly, rinse the III wall with a small amount of water, add 2mL perchloric acid (3.3), heat until smoked, remove and cool slightly, add 8mL hydrochloric acid (3.5) and 10mL water, and heat to dissolve the salts. 5.4.2 Filter into a 100mL beaker with slow quantitative filter paper, wash the platinum blood and residue with hot hydrochloric acid (3.9) 4-5 times each, and then wash the residue with hot water 3-4 times, and retain the filtrate as the main liquid. 5.4.3 Place the residue and the filter paper in a platinum crucible and ash it. Then, transfer to a high temperature furnace at 600~700℃ and burn for 2min, take out and cool. Add 2g sodium bisulfate (3.1), place in a high temperature furnace at 600~700℃ and melt until transparent, and keep for 5min, take out and cool. Leach the molten block with 20mL hydrochloric acid (3.6), wash the platinum crucible with water, and combine the leaching solution with the main solution [If the aluminum content in the residue is less than 0.01%, 5.4.2~5.4.3 operations can be omitted, that is, the solution (5.4.1) can be directly transferred to a 100mL volumetric flask) 5.4.4 Transfer the solution to a 100mL volumetric flask, wash the beaker (or platinum III) with water, control the volume to 6DmL, cool to below 15C, add 20mL copper iron reagent solution (3.14) while shaking, dilute to the scale with water, and mix well. Filter with slow quantitative filter paper. 5.4.5 Take 50.00mL of the filtrate (if the lead content is greater than 0.200%, take 20.00mL), place it in a 100mL quartz conical flask, add 5mL of nitric acid (3.4), heat and evaporate to a small volume, add 2mL of perchloric acid (3.3), continue heating and smoking until the volume is about 1mL, remove it and cool it slightly, add 2ml of hydrochloric acid (3.5) to dissolve the salts. Transfer it to a 50mL volumetric flask, dilute it to the scale with water, and mix it well. 5.4.6 Take two portions of 5.00mL of the solution (5.4.5), place them in two 100mL beakers, add 2 drops of 2,4-nitrophenol solution (3.15) respectively, neutralize it with ammonium hydroxide (3.10) until the yellow color just appears, then neutralize it with hydrochloric acid (3.7) until the yellow color disappears, and immediately add 5mL of hydrochloric acid (3.8).
5.4.6.1 Use one of the solutions (5.4.6) as the reference solution, add 3 drops of ammonium fluoride solution (3.12), 1 mL of ascorbic acid solution (3.13), 5.0 mL of chrome azuro blue S ethanol solution (3.16), and 5 mL of hexamethylenetetramine solution (3.11) in sequence (mix each time a reagent is added). Transfer to a 50 mL volumetric flask, wash the beaker with water, dilute to the mark, and mix. 5.4.6.2 Use another solution (5.4.6) as the color developing solution, add 1 mL of ascorbic acid solution (3.13), 5.0 mL of chrome azuro blue S ethanol solution (3.16), and 5 mL of hexamethylenetetramine solution (3.11) in sequence (mix each time a reagent is added). Transfer to a 50 mL volumetric flask, wash the beaker with water, dilute to the mark, and mix. 5.4.7 After leaving the reference solution 5.4.6.1 and the color developing solution 5.4.6.2 for 15 minutes, transfer part of the solution into a 1 cm colorimetric dish and measure its absorbance at a wavelength of 550 nm using a spectrophotometer, taking the reference solution as the reference. Subtract the absorbance of the blank prepared along with the sample and find out the corresponding aluminum content from the working curve.
5.5 Drawing of working curve
GB4333.4—88
Take two portions of 0, 1.00, 2.00, 4.00, 5.00, 6.50mL aluminum standard solution (3.17.2) and place them in two groups of 100mL beakers respectively. Add water to control the volume to about 10mL. Add 2 drops of 2,4-dinitrophenol solution (3.15) to each beaker. Neutralize with ammonium hydroxide (3.10) until yellow just appears. Then neutralize with hydrochloric acid (3.7) until the yellow disappears. Immediately add 5mL hydrochloric acid (3.8). The following procedures are respectively carried out according to 5.4.6.1 and 5.4.6.2.
After standing for 15 minutes, transfer part of the solution into 1cm colorimetric blood, use 5.5 strips of reference solution as reference, measure its absorbance at a wavelength of 550nm on the spectrophotometer, subtract the absorbance of the reagent blank, and draw a working curve with the amount of aluminum as the horizontal axis and the absorbance as the vertical axis. 6 Calculation of analysis results
Calculate the percentage of aluminum according to the following formula:
Wherein: m1——the amount of aluminum found from the T. curve, g; m.Vr·V3
the volume after dilution when the copper-iron reagent is separated, mL; W2
the volume of the test solution taken after the copper-iron reagent is separated, mL; Vs—the volume diluted after the copper-iron reagent is destroyed, mL; V
the volume of the test solution taken during color development, mL;
the amount of sample,·.
7 Allowable difference
× 100
The difference in analysis results between laboratories should not be greater than the allowable difference listed in the following table. %
0.100~~0. 300
>0.300~~0. 600
Additional Notes:
This standard was drafted by Maanshan Iron and Steel Company. The main drafter of this standard is Li Jun.
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