GB/T 5121.13-1996 Chemical analysis methods for copper and copper alloys - Determination of aluminum content
Some standard content:
National Standard of the People's Republic of China
Chemical analysis methods for copper and copper alloys
Determination of aluminium content
Copper and copper alloys Determination of aluminium content Part I Method 1 Determination of aluminium content by chrome azurol S spectrophotometry 1 Scope
This standard specifies the method for measuring the aluminium content in copper and copper alloys. GB/T 5121.13 1996
Replace (22.
G13 5122. 13
G3 h20, 2
G 8351
This standard is applicable to the determination of aluminum content in copper and copper alloys. Determination range: 0.0010%~0.50%, 2 Referenced standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. The versions shown are valid when this standard is published. All standards will be revised, and parties using this standard should explore the possibility of using the latest version of the listed standards GB1.4·88 Standardization I Guidelines for the preparation of chemical analysis method standards GB1467--78 General principles and general provisions for chemical analysis method standards for metallurgical products G B7729--87 General Rules for Spectrophotometric Methods for Chemical Analysis of Metallurgical Products 3 Method Summary
The sample is dissolved in nitric acid, filtered when metastannic acid precipitates, and copper is removed by electrolysis. The trace aluminum adsorbed by metastannic acid is recovered by treatment with bromic acid, and the lead-benzoylphenylhydroxylamine complex is separated from phosphorus by ethyl acetate benzene, and then the aluminum is stripped and combined with the same main liquid in water. The interference of the human site is electrolytically removed before the copper is removed. When the silicon content is high, it is removed by volatilization with oxyfluoric acid. The influence of chromium is eliminated by adding hydrochloric acid to remove chromium with fuming perfluoric acid! . The interference of beryllium is masked by disodium ethylenediaminetetraacetic acid (CHINONa:·2H0). The beryllium oxide precipitate is separated and removed, and masked with picric acid. The influence of zinc and nickel is offset by adding equal amounts of zinc and nickel in the blank test, and the influence of iron and residues is eliminated with ascorbic acid and sulfuric acid. Other elements present in the copper alloy have no interference. At about pH 6, chrome blue S is used for color development, and its absorbance is measured at a wavelength of 545nm on a spectrophotometer.
4 Reagents
Pure zinc (aluminum content should be less than 0.001%). 4.2
Ethyl acetate.
Extracting agent: 2 units of volume of 4-pentanone-2 are mixed with 1 unit of volume of toluene. Homosalic acid (pl .67g/mL), high-grade purity. 4.4
Hydrobromic acid (pl.49g/mL), high-grade purity. 4.6Hydrofluoric acid (pl.13g/ml). High-grade purity. 4.74
Hydrochloric acid (pl.18g/ml), high-grade purity.
4.8Nitric acid (p1.42g/ml.). High-grade purity. 4.9Nitric acid (1+1), high-grade purity
Approved by the State Administration of Technical Supervision on 199611-04
Implemented on 19970401
Nitric acid (2+98).
4.11 Nitric acid (1+99).
Hydrochloric acid (1+1). Premium purity
Hydrochloric acid (1+39).
Hydrochloric acid [c(HCI) 0. 2 mol/L].
Hydrochloric acid [c(HCI)=0. 1 mol/L].
Ammonia water (1+1). Premium purity.
Ammonia water (1+2). Premium purity.
4.18Ammonia water (1+9), premium purity.
4.19Sulfuric acid (1+1), premium purity.
GB/T 5121. 13-—1996
4.20Nickel solution: Weigh 1.000 pure nickel (aluminum content should be less than 0.005%), add 15mL nitric acid (4.9), heat to dissolve. Boil to remove nitrogen oxides, and cool. Transfer to a 200ml volumetric flask, dilute to scale with water, and mix. This solution contains 5mg nickel in 1ml. 4.21 Beryllium sulfate solution: weigh 9.83g beryllium sulfate (BeS0, *4H.O) (aluminum content should be less than 0.0001%), dissolve the tablet with water, transfer to a 500ml volumetric flask, dilute to scale with water, and mix. This solution contains 1mg beryllium in 1ml. 4.22 Copper solution: weigh 0.100g pure copper, add 5mL nitric acid (1.9), heat to dissolve, boil to remove nitrogen oxides. Cool. Transfer to a 200mL volumetric flask, dilute to scale with water, and mix. This solution contains 0.5mg copper in 1ml. 4.23 Ascorbic acid solution (10g/L), prepare when used. 4.24 Thiourea solution (50g/1.).
4.25 Anhydrous sodium acetate solution (80g/L). 4.261,10 Phenomenal solution (2.5 g/L): Weigh 0.50 g 1.10 Phenomenal (CzHN2·H0), heat with water to dissolve, and cool. Dilute with water to 200 ml, mix.
4.27 Benzoylphenylhydroxylamine ethanol solution (10 g/1.): Store in a brown bottle. 4.28 Mandelic acid solution (10 g/L).
4.29 Disodium ethylenediaminetetraacetic acid (CiaH,N,O,Na2·2H,O) solution [c(CH1,N2O,Naz·2H,O)-0.02 mol/L]: Weigh 7.445 g disodium ethylenediaminetetraacetic acid (CloH4N20gNaz·2H,0), dissolve with 200 mL hot water, cool, transfer to a 1000 ml volumetric flask, dilute with water to the mark, and mix. 4.30 Chrome azure S solution (0.6 g/L).
4.31 p-Nitrophenol solution (2 g/1).
4.32 Aluminum standard stock solution: Weigh 0.1000 g pure aluminum and place it in a 150 mL polytetrafluoroethylene beaker, add 10 mL water and 1 g sodium hydroxide, heat at low temperature to dissolve, and cool. Slowly neutralize with hydrochloric acid (4.12) until precipitation appears, then add 20 ml hydrochloric acid (4.12): transfer to a 1000 ml volumetric flask, dilute to scale with water, and mix. This solution contains 100 ug aluminum in 1 ml. 4.33 Aluminum standard solution: Transfer 5.00 mL aluminum standard stock solution (4.32) to a 500 mL volumetric flask, add 5 ml hydrochloric acid (1.12). Dilute to scale with water, and mix. This solution contains 1 μg aluminum in 1 ml. 4.34 Aluminum standard solution: Pipette 15.00 mL of aluminum standard purchased solution (4.32) into a 500 mL volumetric flask, add 5 mL of hydrochloric acid (4.12), dilute to the mark with water, and mix. This solution contains 3 μg aluminum in 1 mL. 5 Instruments
5.1 Spectrophotometer.
5.2 Electrolyzer: Equipped with a stirrer, precision ammeter and voltmeter. 5.3 Electrodes: Mesh platinum cathode, spiral platinum anode. 6 Analysis steps
6.1 Test materials
GB/T512113---1996
Weigh the sample according to Table 1, accurate to 0.0001 g. Table 1
Aluminum content,
0. 001 0~0. 005 0
2= 0. 005 0 ~~0. 015
20.016～0. 040
20. 010-~ 0. 10
0. 10 0. 25
0. 25--0. 50
Sample basis·g
Carry out a measurement independently and take the average value. 6.2 Blank test
6.2.1 Carry out a blank test with the sample.
Nitric acid (4.9).ml.
Total amount of test solution.m
Service test micro-body and
6.2.2 When analyzing brass and tin bronze, weigh pure zinc (4.1) in an amount similar to that in the sample, and perform a self-test with the sample. 6.2.3 When analyzing silicon bronze, transfer nickel solution to make its nickel content similar to that in the sample. Perform a self-test with the sample. 6.2.4 When analyzing beryllium bronze, transfer beryllium sulfate solution to make its beryllium content similar to that in the sample, and perform a self-test with the sample. 6.3 Determination
6.3.1 Dissolution of sample
6.3.1.1 Nickel brass, lead brass, iron brass, manganese brass, manganese bronze and manganese white copper samples. 6.3.1.1.1 Place the sample (6.1) in a 250mL electrolytic beaker, add nitric acid (4.9) according to Table 1, heat to dissolve, boil off all oxides, and cool. If metastannic acid precipitates are found at this time, evaporate the solution to 1~2ml, cool slightly, add 5ml nitric acid (4.9), heat to 25ml, and age at 85~~95C for 20min. Filter while hot with quantitative filter paper that has been washed with nitric acid (4.11) in advance, wash the precipitate and burn 3~4 times with hot nitric acid (1.11), and combine the filtrate and washing liquid. 6.3.1.1.2 Dilute with water to about 80ml, add 1 drop of hydrochloric acid (4.15), and electrolyze copper at 2A current. 6.3.1.1.3 After the solution fades, electrolyze for another 10min.Rinse the cup wall with water and then electrolyze for 5 minutes. If the newly submerged electrode does not need to precipitate copper, the electrolysis is complete. Remove the electrode quickly without cutting off the current and rinse with a small amount of water. 6.3.1.1.4 After the solution after copper removal is cooled, transfer it to a volumetric flask according to Table 1, dilute it to the scale with water, and mix it. 6.3.1.1.5 Transfer the test solution according to Table 1 to a 150mL quartz beaker, evaporate it to dryness, and cool it. The following is carried out according to 6.3.2~G.3.1.6.3.1.2 Tin-backed copper sample
6.3.1.2.1 Place the sample (6.1) in a 150mL quartz beaker, add nitric acid (4.9) according to Table 1. Heat to dissolve, boil to remove nitrogen oxides, heat the water to 50ml, and age it at 85~~95C for 1h. While hot, filter the solution into a 150mL quartz beaker using a slow quantitative filter paper that has been previously washed with nitric acid (4.11). Wash the beaker and the precipitate 3 to 4 times with hot nitric acid (4.11). Combine the filtrate and washing liquid (preserve the precipitate and filter paper). Dilute with water to about 80ml. Add 1 drop of hydrochloric acid (4.15) and electrolyze to remove copper at a current of 2A. When the lead content is greater than 1%, first use a mesh platinum electrode as the anode and a spiral platinum electrode as the cathode, and electrolyze for 30 minutes at a current of 1A to remove most of the lead. Remove the electrode quickly without cutting off the current, rinse with a small amount of water, then add 1 drop of hydrochloric acid (4.15), and electrolyze to remove copper at a current of 2A using a clean platinum electrode. The following is carried out according to 6.3.1.1.3.
6.3.1.2.2 Place the retained precipitate and filter paper into the original quartz beaker and add 5ml of nitric acid (4.8). 7ml. chloric acid, heat the high acid until it smokes and completely decomposes the organic matter, cool slightly. Rinse the wall with a small amount of water, add 5ml. hydrobromic acid, and evaporate until it smokes. Cool slightly and add 3mL hydrobromic acid, evaporate until white smoke appears. If the solution is still turbid, add 3ml hydrobromic acid and repeat the process until the solution is completely clear: 239
GB/T 5121. 13--- 1996
6.3.1.2.3 When the phosphorus content is less than or equal to 0.03%, add 5ml nitric acid (4.9). Heat to boil to dissolve the salts and cool. Transfer the electrolyte (6, 3.1.2.1) in Table 15 into the same volumetric flask, dilute with water to the scale, and mix well. 6.3.1.2.4 If the phosphorus content is not less than 0.03%, add 5ml of hydrochloric acid (4.12) to the beaker (6.3.1.2.2). Boil to dissolve the heat, cool. Transfer to a 60ml separatory funnel, wash the beaker with 10ml of hydrochloric acid (4.12) in batches, and add the washing liquid to the separatory funnel. Add 1ml, take the agent, shake for 30 minutes, and then transfer the water to a 150ml quartz beaker. Add 5ml of hydrochloric acid (1.12) to the organic phase, shake for 10 minutes, and then remove the water phase and combine it with the previous water phase. Evaporate to 1~2mL and cool. 6.3.1.2.5 Add 25ml of water, 5ml of 1.10-phenanthroline solution, and 2ml of benzyl alcohol hydroxylamine ethanol solution. Add 1.0% each! All reagents must be mixed, add 1 drop of p-nitrophenol solution, neutralize with ammonia (4.17) until yellow and add 2 ml excess. Transfer to a 60 mL liquid beaker, wash the beaker with water, add the washing liquid to the hair liquid, squeeze the volume to about 40 mL, and let it stand for 10 minutes. Add 20 ml of acid. Oscillate: 1 minute, stand for phase separation, and remove the aqueous phase. Add 10 mL of water to the organic phase and oscillate for 10 seconds. Stand for phase separation, and discard the aqueous phase: Add 5 ml of water to the organic phase, oscillate for 10 seconds. Stand for phase separation, and remove the water and. Add 10 ml of hydrochloric acid (4.11) to the organic phase, oscillate for 1 minute. After leaving the differential phase, transfer the aqueous phase to a 150 mL quartz beaker. Add 5 ml of hydrochloric acid (1.14) to the organic phase, oscillate for 1 minute. Stand for phase separation, remove the aqueous phase and combine it with the previous aqueous phase. Evaporate to 3~5 mL and cool. Transfer the test solution (6.3.1.2.1) and electrolyte (6.3.1.2.1) to a container according to Table 1, dilute to the mark with water, and mix.
6.3.1.2.6 Transfer the test solution (6.3.1.2.3 or 6.3.1.2.5) to a 150ml quartz beaker according to Table 1, add 1ml copper solution, evaporate to 2~3ml, continue evaporation under constant shaking until just dry, and cool. The following shall be carried out according to 6.3.2~6.3.1. 6.3.1.3 Beryllium bronze test sample
6.3.1.3.1 Place the test sample (6.1) in a 250ml electrolytic beaker, add nitric acid (4.9) according to Table 1, heat to dissolve, boil to remove nitrogen oxides, and cool. The following shall be carried out according to 6.3.1.1.26.3.1.1.3. 6.3.1.3.2 Evaporate the solution after copper removal to about 70ml, and cool. Add 15ml NazFDTA solution, slowly neutralize with ammonia water (t.16) under constant stirring until precipitation appears and heat to boiling with an excess of 10ml, cool to room temperature, transfer to a container according to Table 1, dilute to scale with a small amount, mix, and cover for 10-15min. 6.3.1.3.3 Filter with quantitative filter paper, discard the initial filtrate, transfer the subsequent filtrate to 150ml in a beaker according to length 1, add 1ml sulfuric acid, place on an electric hot plate 1 and evaporate until nearly dry, then place on a high-temperature electric furnace and evaporate until white smoke disappears, and cool. The following is carried out according to 6.3.2~6.3, 4. 6.3.1.4 Chrome bronze test sample
6.3.1.4.1 Place the test sample (6.1) in a 150mL quartz beaker, add nitric acid (4.9) according to Table 1, heat and dissolve, add 5ml perchloric acid, evaporate until white perfluoric acid smoke appears, place on a high temperature electric furnace and evaporate until thick white perchloric acid smoke appears, immediately add 1ml hydrochloric acid (4.7) while shaking continuously, then evaporate again until thick white perfluoric acid smoke appears, and add hydrochloric acid (4.7) as above. Repeat this process 3 to 1 times. Place on a hot plate and evaporate for 3 to 10 minutes, then cool.
6.3.7.4.2 Add 5ml nitric acid (4.9) and 20mL water, heat to boil to dissolve salts, and remove nitrogen oxides. Cool. The following shall be carried out according to 6.3.1.1.2 to 6.3.1.1.5. 6.3.1.5 Light bronze and silicon brass test sample
6.3.1.5.1 Place the test sample (6.1) in 100mL of platinum III, add nitric acid (4.9) according to Table 1. After heating and dissolving, add 10ml of sulfur and 1.5ml of fluoric acid, evaporate until thick sulfuric acid white smoke appears. Cool. Add 30~40ml of water and 3ml of nitric acid (4.9). Heat and dissolve the disk. Cool. Transfer to a 250ml electrolytic beaker and dilute with water to about 80ml. Electrolytically remove copper at a current of 2A. Proceed as follows in 6.3.1.1.3 to 6.3.1.1.4.
6.3.1.5.2 Transfer the test solution according to Table 1 to a 150ml quartz beaker, evaporate it on a hot plate until it is nearly 1/4, then evaporate it in a high-temperature electric furnace until the smoke is gone, and cool. Proceed as follows in 6.3.2 to 6.3.4. 6.3.2 Dissolved salts
Add 5 ml of nitric acid (4.10) to a beaker (6.3.1.1.5 or 6.3.1.2.6 or 6.3.1.3.3 or 6.3.1.4.2 or 6.3.1.3.2), heat to boil to dissolve the salts, and cool. If sample 1 contains titanium, add 2 ml of bitter acid solution 6.3.3 Color development
Add 1 drop of p-nitrophenol solution, neutralize with ammonia water (4.18) until yellow, and then use hydrochloric acid (4.13) to neutralize until the yellow color disappears. Excess 260
GB/T 5121. 13 --- 1996
2.00 mL. Add 1.0 mL of ascorbic acid solution and 5.0 mL of sulfuric acid solution. Each reagent must be mixed well. Transfer to a 50ml volumetric flask, add 3.00ml of chrome blue S solution and mix. Add 5.0ml of anhydrous sodium acetate solution and mix. Dilute to the mark with water, stir and place for 5min (place for 15min when the temperature is below 15). 6.3.4 Measurement
Transfer part of the test solution to a 1cm (3m when the sample is 2g) absorption dish, use the empty solution accompanying the sample as a reference, measure its absorbance at a wavelength of 545nm on a spectrophotometer, and find the corresponding aluminum content from the T curve. 6.4 Drawing of the working curve
6.4.1 Transfer 0, 1.00, 2.00, 3.00, 4.00, 5.00mL of lead standard solution (4 .33 or 4.34) are placed in a 150ml beaker and 5ml of nitric acid (4.10) is added. If the sample contains titanium, add 2mL of bitter benzyl acid solution. The following is carried out according to 6.3.3. 6.4.2 Pipette part of the test solution F3cm or 1cm absorption III, and measure its absorbance at a wavelength of 545mm on a spectrophotometer with the reagent blank as a reference. Draw a working curve with the amount of lead as the horizontal axis and the absorbance as the vertical axis. Expression of analysis results
Calculate the percentage of aluminum according to formula (1):
mz:V× 10--
A1(%) =-
Where: mt-·-The amount of aluminum found on the white working curve, ug; V.Total volume of test solution, mL;
V.-.. Volume of test solution taken, mL.
The mass of the test material, g.
The result is expressed to two decimal places. If the aluminum content is less than 0.10%, it is expressed to 3 decimal places. If it is less than 0.010%, it is expressed to 1 decimal place.
8 Allowable difference
The difference between the analysis results of laboratories should not be greater than the allowable difference listed in Table 2. Table 2
0. 001 0~~0. 003 0
>0. 003 0~0. 006 0
>0. 006 0-- 0. 015
0. 015-0. 030
0. 030-~0. 050
0. 050~0. 10
0. 10~0. 25
>0.25~0.50
9 Scope
GB/T 5121. 13—1996
Part II Method 2 Determination of aluminum content by benzoic acid separation-ethylenediaminetetraacetic acid disodium complexometric titration
This standard specifies the method for determining the aluminum content in copper and copper alloys. This standard is applicable to the determination of aluminum content in copper and copper alloys. Determination range: >0.50%～12.00%. 10 Reference standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and the parties using this standard should explore the possibility of using the latest versions of the following standards. GB1.4--88 Guidelines for standardization work, provisions for the preparation of chemical analysis methods, GB1467-78 General principles and general provisions for chemical analysis methods for metallurgical products 11 Method summary
The sample is dissolved in nitric acid, and the pH value of the solution is adjusted with ammonia water and hydrochloric acid. In the presence of buffer solution and hydroxylamine hydrochloride, lead and ammonium benzoate are precipitated and filtered. The precipitate is dissolved in hydrochloric acid, and an excess of disodium ethylenediaminetetraacetate (C1HuN.O.Na2·2HO) is added. Use p-nitrophenol as an indicator, adjust the acidity with ammonia water and hydrochloric acid, boil, and cool. Add hexamethylenetetramine, use xylenol orange as an indicator, and titrate the excess disodium ethylenediaminetetraacetate (C1HnN.O.Na·2H,O) with a standard zinc solution. Add sodium fluoride, boil, and cool. Titrate the released disodium ethylenediaminetetraacetate (CHi,N,O.Na2·2H,O) with a standard zinc solution. 12 Reagents
12.1 Sodium fluoride.
12.2 Nitric acid (1+1).
12.3 Hydrochloric acid (1+1).
12.4 Hydrochloric acid (1+2).
12.5 Hydrochloric acid Lc(HCI)=1 mol/L7.
12.6 Aqueous ammonia (p0.90g/mL).
12.7 Buffer solution: Dissolve 120g of anhydrous sodium acetate in water, add 130mL of hydrochloric acid (12.3), dilute to 1000ml with water, and mix. The solution is about pH 4.4.
12.8 Hydroxylamine hydrochloride solution (100g/L). 12.9 Ammonium benzoate solution (80g/L).
12.10 Ammonium benzoate wash solution: Mix 400mL of water, 50ml of ammonium benzoate solution (12.9) and 50ml of hydroxylamine hydrochloride solution (12.8) with hexamethylenetetramine solution (300g/L). 12.112www.bzxz.net
Acetic acid (1+1): Prepare with 36% acetic acid.
P-nitrophenol solution (2g/L).
Xylenol orange solution (2g/L).
5 Disodium ethylenediaminetetraacetate (C1oHμN20,Naz2H,0) standard solution [c(CHN,ONa·2HzO)0.025 tmol/12.15
LJ. Dissolve 9.3g disodium ethylenediaminetetraacetate (CH1aN.O.Naz·2H,0) in about 200ml hot water, cool and transfer to a 1000ml volumetric flask, dilute to scale with water, and mix well. 12.16 Aluminum standard solution: Weigh 1.000g pure aluminum and place it in a 150ml polytetrafluoroethylene beaker, add 20mL sodium hydroxide solution (300/L), slowly heat and dissolve completely, and cool. Use hydrochloric acid (12.3) to adjust until the precipitate disappears and the solution is clear. At this time, the solution is acidic, cool and transfer to a 1000mL volumetric flask, dilute to scale with water, and mix well. This solution contains 1mg lead per ml. 262
GB/T5121.13--1996
12.17 Zinc standard titration solution "c (Zn) 0.02000mo)/L7. 12.17.1 Preparation
Weigh 1.308g pure zinc and place it in a 300mL beaker. Dissolve it with as little hydrochloric acid (12.3) as possible, adjust to 112~~3, transfer it to a 1000mL volumetric flask, dilute with water to the scale, and mix well. 12.17.2 Calibration
Transfer 10.00mL aluminum standard solution (12.16)" into a 300ml beaker, and proceed as per 13.2.4~13.2.7. Calculate the actual concentration of zinc standard titration solution according to formula (2): 0.010 0
V, X 0. 026 98
Wherein: c—actual concentration of zinc standard titration solution, mol/L: V.—volume of zinc standard titration solution consumed during calibration, mL; 0.02698—mass of aluminum equivalent to 1.00ml zinc standard titration solution c(Zn)=1.00)mol/L], g/mol. (2)
Take 3 portions for calibration. The range of the consumed zinc standard titration solution does not exceed 0.10ml. Take the average value. If the range is less than 0.10ml, recalibrate.
13 Analysis steps
13.1 Sample
Weigh the sample according to Table 3 to an accuracy of 0.0001g. Table 3
Aluminum content, %
>0.50~4.00
>4.00~6.00
-6.00 ~8.00
78.00~12.00
Carry out two independent determinations and take the average value. 73.2 Determination
13.2.1 Place the sample (13.1) in a 300mL beaker, add 10mL nitric acid, heat to dissolve completely, and boil to remove nitrogen oxides. If metastannic acid precipitation is found, evaporate the solution to about 3mL, add a small amount of water, boil, and cool. 13.2.2 Add water to a volume of about 80mL, add ammonia water dropwise until a small amount of precipitation is produced (stir with a glass rod while adding, and try not to let the precipitation adhere to the inner wall of the beaker during operation), and immediately add hydrochloric acid (12.4) dropwise to dissolve the precipitation. Add 70 ml of buffer and 5 ml of hydroxylamine hydrochloride solution, heat to boil, add 25 ml of ammonium benzoate solution, stir thoroughly, and place on a hot plate at low temperature for 20 minutes to age the precipitate.
13.2.3 Filter with rapid quantitative filter paper, wash the beaker twice and the precipitate twice with hot ammonium benzoate solution. Use a glass rod to transfer part of the precipitate to the original beaker, and then add 10 ml of hot hydrochloric acid (12.4) dropwise three times to dissolve the remaining precipitate. After each addition of hot hydrochloric acid, wash the precipitate and filter paper with hot water for 1 to 2 times, and finally wash the filter paper with hot water for 4 times. Heat and boil to completely dissolve the precipitate, and cool. 13.2.4 Add disodium ethylenediaminetetraacetic acid (CH14N2O.Na2·2H2O) standard solution according to Table 4. 263
Amount, %
≥0.50~1. 00
1. 00~-3. 00
>3. 00~~3. 50
>3. 50~6. 00
26. 00~8. 00
>8. 00~12. 00
GB/T 5121.13—1996
Volume of disodium ethylenediaminetetraacetate (CHN2:Na2·2H.0) standard solution, mL
Volume of excess hydrochloric acid (12.5). ml.
13.2.5 Add 2 drops of p-nitrophenol solution, neutralize with ammonia until the solution turns yellow, then add hydrochloric acid (12.5) dropwise until the solution turns colorless, and then add a certain excess of hydrochloric acid (12.5) according to the aluminum content according to Table 2. Add water to a solution volume of about 100 mL, heat and boil for about 1.5 minutes, and cool. 13.2.6 Add 5 mL of hexamethylenetetramine solution and 4 drops of monocresol orange solution, and titrate with zinc standard titration solution until the solution changes from yellow to purple-red (ignoring the volume).
13.2.7 Add 1g of sodium fluoride to the solution, boil for 1min, and cool. Add acetic acid solution and it turns yellow. Titrate with zinc standard titration solution until the solution changes from yellow to purple-red. 14 Expression of analysis results
Calculate the percentage of aluminum according to formula (2):
Al(%) · V, × 0. 026 98
Where: - the actual concentration of zinc standard titration solution, mol/L. - the volume of zinc standard titration solution consumed during titration, mL; Va
the mass of the sample, g;
0.02698 - the mass of aluminum equivalent to 1.00mL zinc standard titration solution [c(Zn)=1.000mol/L], g/mol. The result is expressed to two decimal places.
Allowable difference
The difference between the analysis results of laboratories shall not be greater than the allowable difference listed in Table 5: Table 5
20. 50~2. 00
2. 00 ~ 4. 00
>4. 00-~8. 00
≥8. 00~12. 00
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