GB/T 3044-1989 Chemical analysis methods for white corundum and chrome corundum
Some standard content:
Evenly, put it into the sample, dry it and set it aside. GB 3044-89
For samples finer than No. 100 particle size, use the quartering method to reduce it to more than 20, put it into the sample bag, dry it and set it aside. For samples used for acid melting and flame photometry, use corundum grinding body to grind it until it can all pass through the No. 180 sieve. 4 Measurement of ignition loss (or ignition increase)
4.1 Analysis steps
Weigh 1g of the prepared sample and place it in a platinum pot that has been burned at 1100℃ to constant weight, cover it, slightly open the lid, cover the platinum coil in a high-temperature furnace, burn it at 1100℃ for 1h, take it out, place it in a desiccator, cool it to room temperature, weigh it, and repeat the burning until constant weight. 4.2 Calculation of analysis results
The ignition loss (or ignition increase) expressed as a mass percentage is calculated according to formula (1): ignition loss (or ignition increase) =
- weight of the sample before ignition,
where
m. —— weight of the sample after ignition + m - weight of the sample, g.
ml = m= × 100
Note that corundum products sometimes have ignition increase. If the calculated result is a negative value, it is ignition increase. 4.3 Allowable error
The allowable error shall be in accordance with the provisions of Table 1.
Same laboratory
"Different laboratories
5 Determination of silicon dihydride by molybdenum blue photometry
: 5.1 Method summary
(1)
After the sample is decomposed, add ammonium molybdate to the 0.08~～0.32N hydrochloric acid medium to make the silicate ions form silicomolybdic heteropoly acid, and use 1,2,4-acid reducing agent to reduce it to molybdenum blue, and measure its absorbance at a wavelength of 700nm on a spectrophotometer. 5.2 Reagents|| tt||5.21 Borax-sodium carbonate mixed flux: Weigh two parts of borax and one part of anhydrous sodium carbonate in an agate mortar, grind them into a fine powder, mix well, and store in a wide-mouth bottle.
5.2.2 Hydrochloric acid (15+85).
5.2.3 Ammonium molybdate solution, 5%. Dissolve 5g of ammonium molybdate in water, dilute to 100mL with water, let stand for 24 hours, filter and use. If precipitation occurs, stop using it.
5.2.4 Tartaric acid solution: 5%. || tt||5.2.5 1,2,4-acid reducing agent solution: Dissolve 1,2,4-acid (1-amino-2-phenol-4-sulfonic acid>0.15g, anhydrous sodium sulfite 0.7g, sodium sulfite 9g, in water, dilute with water to 100mL, and store in a plastic bottle. The shelf life of this solution is 14 days. 5.2.6 Silica, high-purity reagent or spectrally pure reagent. 5.2.7 Silica standard solution: Accurately weigh silica (high-purity) calcined at 1000℃ 0.1000g of sodium carbonate (standard reagent) was placed in a platinum crucible, and 2g of anhydrous sodium carbonate (standard reagent) was added to mix carefully, and then covered with 0.5g, and sent to a high-temperature furnace, melted at 860~900℃ for 20min, taken out, rotated, and the molten material adhered to the inner wall, cooled, and the outer wall was cleaned, and poured with hot water in a mulberry beaker, and then transferred to a 1000mL volumetric flask, diluted with water to the scale, shaken, and immediately transferred to a clean and dried plastic bottle for storage for later use (containing 0. 1 mg/mL).
GB 3044—89
Take 100 mL of the above silicon dioxide solution into a 200 mL volumetric flask pre-filled with 10 mL of hydrochloric acid (2 N), dilute to the mark with water, and shake well to obtain the silicon dioxide standard solution (containing 0.5 mg/mL silicon dioxide). 5.2.8 Blank solution: Take 4 B mixed flux into a platinum crucible, melt it in a high-temperature furnace at 1 000°C for 20 min, take it out, and clean the outer wall of the crucible; heat and leach it with 100 mL of hydrochloric acid (15+85), transfer it into a 250 mL volumetric flask, and dilute to the mark with water after cooling. Shake well. 5.3 Drawing of working curve
Take 8 portions of blank solution, 25 mL each, and put them into 9 1 000°C furnaces respectively. tnL volumetric bottle, use a microburette to add 0:00, 0.20, 0.50, 1.00, 1.50, 2.00, 3.00, 5.00mL of silica standard solution in sequence, add water to 60mL, adjust the test solution temperature to 20-25℃, add 5mL of ammonium chloride solution (5%, let stand for 10min, add 20mL of tartaric acid solution (5%). 3ml of 1,2,4-acid reducing agent solution, dilute to the scale with water, shake, let stand for 30min, use water as a reference, measure its absorbance at a wavelength of 700nm on a spectrophotometer with a 2cm colorimetric blood, and draw a working curve after subtracting the absorbance of the blank. 5.4 Preparation of test solution
Accurately weigh 0.500 0 g of the sample and place it in platinum glass. Add 3 g of mixed flux and stir evenly. Then add 1 g of mixed flux and place it in a high-temperature furnace at 1050°C to melt for 1 h. Take it out and rotate the crucible to make the molten material adhere to the inner wall of the crucible. After cooling, wash the outer wall of the crucible with water and place it in a 250 mL beaker with 100 mL of nearly boiling hydrochloric acid (15+85) on the wall. Heat and leach it on a sand bath. Wash out the crucible and lid with water and transfer it to a 250 mL volumetric flask. After cooling, dilute it to the scale with water and shake it evenly. 5.5 Analysis steps
Put 25mL of the test solution (see 5.4) in a 100mL volumetric flask, add 35mL of water, adjust the temperature of the test solution to 20-25℃, add 5mL of ammonium tartrate solution (5%), let it stand for 10min, add 20mL of tartaric acid solution (5%) and 3mL of 1,2,4-acid reducing agent solution, dilute to the scale with water, add water, let it stand for 30min, use water as a reference, measure its absorbance at a wavelength of 700nm on a spectrophotometer with a 2cm colorimetric tube, subtract the absorbance of the blank test, and find out the silicon dioxide content on the working curve. 5.6 Calculation of analysis results
The percentage of silicon dioxide is calculated according to formula (2): Sio (%)
Wherein: m,
Silicon dioxide amount found from the working curve, g sample weight g
V—volume of the test solution, mL;
V—total volume of the test solution, mL.
5.7 Allowable error
The allowable error is as specified in Table 2.
Content range
0. 11~0. 25
0.26~0.50
Same laboratory
Allowable error
Different laboratories
6 Determination of 2-nitropropene trifluoride by phthalocyanine photometric method 6.1 Summary of method
GB 3044—89
High-valent iron is reduced to ferrous iron with carboxyammonium hydrochloride. In the range of pH 2 to 9., ferrous iron and 2-nitropropene form an orange-red complex, and its absorbance is measured at a wavelength of 510nm on a spectrophotometer. 6.2 Reagents
6.2.1 Borax-sodium carbonate mixed flux, see 5.2.1. 6.2.2 Blank filtration, take 4g of mixed flux into a platinum crucible, send the crucible into a high-temperature furnace at 1.000C to melt for 20min, take it out and cool it, wash the outer wall, add 100mL of hydrochloric acid (15±85), heat it up, transfer it into a 200mL volumetric flask, cool it, dilute it with water to the scale, and shake it well.
6.2.3 Tartaric acid solution: 5%.
6.2.4 Hydroxylamine hydrochloride solution: 5%.
6.2.5 o-nitrophenol indicator solution: 0.1%. 6.2.6 Nitrogen water (1+1).
6.2.7 Hydrochloric acid (1+1).
6.2.8 o-Phenanthrene solution: 0.1%. Dissolve 0.1g o-phenanthroline in 10ml ethanol (95%), and dilute to 100mL with water. 6.2.9 Ferric oxide: high-purity reagent or spectrally pure reagent. 6.2.10 Ferric oxide standard solution: Accurately weigh 0.2500g of ferric oxide (high-purity reagent) dried at 110℃ for 2 hours in a 300mL beaker, add 40mL of hydrochloric acid (1+1), add surface III, heat and dissolve on a low-temperature sand bath, wait until it is completely dissolved, cool, transfer to a 1000mL volumetric flask, dilute to the mark with water, shake well, and set aside (containing 0.25mg/mL of ferric oxide). Take 100mL of the above ferric oxide solution, put it in a 1000mL volumetric flask, add 8mL of hydrochloric acid, dilute to the mark with water, shake well, and it is the ferric oxide standard solution (containing 0.025mg/mL of ferric oxide). 6.3 Drawing of working curve
Take 9 portions of blank solution, 20 mL each, and put them into 9 50 mL volumetric flasks respectively. Use a microburette to add 0.000.20, 0.40, 1.00, 2.00, 4.00.6.00.8.00, 10.00mL, add 5mL of tartaric acid solution (5%), and use a pipette to add 2nL of hydroxylamine hydrochloride solution (5%). Two drops of o-nitrophenol indicator, adjust to yellow with ammonia (1+1), and then adjust with 1% ethyl acetate (1+1) until the yellow just disappears, and then add 3 drops of 1% phenanthroline solution (0.1%)>5mL, and heat in a boiling water bath for 5min. Cool, dilute to the scale with water, spread evenly, use water as a reference, and measure its absorbance at 510μm on the spectrophotometer with a 1cm colorimetric blood. After subtracting the absorbance of the blank test, draw a working curve. 6.4 Analysis steps
Take 25ml of the test solution (see 5.4) in a 50mL volumetric flask, add 5mL of tartaric acid solution (5%), and use a pipette to add hydroxylamine hydrochloride solution (5 %) 2ml, two drops of o-nitrophenol indicator, adjust with ammonia water (1+1) until yellow, then adjust with hydrochloric acid (1+1) until the yellow just disappears, then add 3 drops in excess, add 5mL of o-phenanthroline solution (0.1%), shake, heat in a boiling water bath for 5min, cool, dilute to scale with water, spread evenly, use water as a reference, measure its absorbance at a wavelength of 510nm on a spectrophotometer, and at the same time do a blank test under the same conditions, subtract the absorbance of the blank test, and find out the amount of blue iron oxide on the working curve. 6.5 Calculation of analysis results
The percentage of ferric oxide is calculated according to formula (3): Fe0.(%) =
Wherein: m,——the amount of ferric oxide found from the working curve, g1× 100
weight of the sample, g3
Vtotal volume of the test solution, mL;
V,——volume of the test solution taken, ml
6.6 Allowable error
The allowable error shall be in accordance with the provisions of Table 3.
Same laboratory
Different laboratories
7 Determination of sodium oxide by boric acid fusion-flame photometry 7.1 Summary of the method
GB 3044—89
The sample is decomposed with acid, and the sodium therein reacts with nicotinic acid to form sodium borate. After diluting and separating with dilute hydrochloric acid, the sodium oxide content is determined by flame spectrophotometry.
7.2 Reagents
7. 2. 1 Ketoacid; -grade reagent.
7.2.2, hydrochloric acid (3+97).
7.2+3 sodium oxide: high purity reagent.
7.2.4 sodium oxide standard solution: accurately weigh 0.3772 g of sodium oxide (high purity reagent) dried at 110°C for 2 hours in 100 ml, dissolve in water in a beaker, transfer to a 1 000 ml volumetric flask, dilute to the mark with water, add a pinch, and you have the sodium oxide standard solution (containing 0.2 mg/mL).
7.2.5 Blank solution: Dissolve 8g of boric acid in water, add 2mL of hydrochloric acid, transfer to a 250mL volumetric flask, dilute to scale with water, and shake. 7.3 Instrument
Flame spectrophotometer.
7.4 Drawing of working curve
Weigh 9 portions of blank solution, 25mL each, and put them into 9 100mL volumetric flasks respectively. Use a microburette to add 0.00, 0.50, 1.00, 2.00., 3.00, 4.00, 6, 00.8.00, 10.00mL of sodium oxide standard solution in sequence, dilute to scale with water, and shake. Select appropriate working conditions on the flame photometer, measure its galvanometer value (i), and draw the working curve after subtracting the galvanometer value of the blank test. 7.5 Analysis steps
Weigh 0.5000g of sample (fineer than No. 180) into a platinum crucible, mix with 1.5g of boric acid, and then add 0.5g of boric acid. Cover with a lid, slightly open, and cover with a porcelain crucible of appropriate size. Heat on a bright silk electric furnace. After most of the water has been removed, send the platinum crucible into a high-temperature furnace at 980°C to melt for 30min. Take it out, cool it, wash the outer wall, heat and leach it in a 250mL G-type beaker with 100mL of hot hydrochloric acid (3+97), transfer it to a 250mL volumetric flask, cool it, dilute it to the scale with water, sow it, wait for the residue to settle, dry filter it, take part of the filtrate on a flame spectrophotometer, and determine its galvanometer value f(i) under the same working conditions as those used to draw the working curve. After subtracting the galvanometer value of the blank test, find out the content of sodium oxide on the working curve. 7.6 Calculation of analysis results
The percentage of sodium oxide is calculated according to formula (4): Na,0 (%) = m × 2. 5
Wherein, m,—the amount of sodium oxide obtained from the working curve, g; sample size·B.
7.7 Allowable error
The allowable error is in accordance with the provisions of Table 4.
Content range
0.26~0.50
0.51~~1.00
Determination of dioxide by spectrophotometry of saccharide salts 8.1 Summary of the method
GB 3044—89
Same laboratory
Allowable error
Different test cases
After the sample is eutectic with the mixed flux, it is poured out with water and then spectrophotometrically determined in an alkaline solution to obtain the yellow color of the saccharide itself to obtain the content of saccharide.
8.2 Reagents
B.2.1 Sodium borophosphate mixed flux (see 5.2.1), B.2.2 Potassium dichromate; reference reagent.
8.2.3 Chromium trioxide standard solution: Accurately weigh 0.4839 g of potassium monochromate (reference reagent) dried at 110℃ for 2 h in a 100 mL beaker, add water to dissolve, transfer to a 1 000 mL volumetric flask, add water to dilute to the mark, spread evenly, and this is the chromium trioxide standard solution (containing 0.25 mg/mL of chromium trioxide).
8. 2.4 Blank solution: Weigh 8 g of mixed flux in platinum crucible, melt the crucible in a high temperature furnace at 1 000℃ for 20 min, take out and clean the outer wall of the crucible, and use hot water to remove the melt in a 300mL beaker. After washing the crucible, add 4g of sodium hydroxide, cool it slightly and transfer it to a 250mL volumetric flask. After cooling, dilute it with water to the scale, and set aside. 8.3 Drawing of working curve
Take 7 portions of blank solution, 25mL each, and put them into 50mL volumetric flasks respectively. Use a microburette to add 0.00, 1.00, 2.00, 4.00, 6.00, 8.00, 10.00 mL of chromium trioxide standard solution in turn, dilute it with water to the scale, and spread it evenly. Using water as reference, measure the absorbance at a wavelength of 420 nm on a spectrophotometer with 2 cm colorimetric blood, and draw a working curve after subtracting the absorbance of the blank. 8.4, Analysis steps
Accurately weigh 0.5000 g of the sample into a platinum crucible, add 3 g of mixed flux, stir evenly, then add 1 g of mixed flux, cover with a lid slightly open, put the mixture into a high temperature crucible, melt at 1 060-1 100 ℃ for 1 h, take it out, turn the crucible to make the molten material adhere to the inner wall of the crucible, after cooling, wash the outer wall of the crucible, put it in a 300m2L beaker, use 100mL boiling water on a hot water bath until the molten mass is completely condensed, wash out the crucible and the lid, add 2 B of sodium hydroxide, boil slightly on sand for 20 min, take it out, transfer it into a 250-inL volumetric flask, cool it, dilute it to the scale with water, shake it evenly (dry filter if there is precipitation). Using water as reference, measure its absorbance at a wavelength of 420 nm on a spectrophotometer with a 2 cm colorimetric solution. After subtracting the absorbance of the blank test, find out the content of chromium trioxide on the working curve. 8.5 Calculation of analysis results
The percentage of chromium trioxide is calculated according to formula (5): Cr,O,(%) = m X 5
Where: m, — the amount of chromium trioxide found on the working curve + m; sample weight g.
(5)
8.6 Allowable error
The allowable error is as specified in Table 5.
Content Range
0, 51~1. 00
1. 01 ~~2. 50
Determination of blue aluminum fluoride
G- 3044-89
Same test plug
Allowable error
Al2O3 in white corundum and skeletal corundum is not directly determined. After determining the impurity content, it is obtained by the filtration method. 9.1 Calculation of aluminum oxide content in white jade The percentage of aluminum oxide in white corundum is calculated according to formula (6): Al,0g(%) = 100 - (wso, + W,0, + wNz,0 + ignition reduction) In the formula; su. ——Silicon dioxide content, %; Wpe,o,
Fe2O3 content, %
WNz0 ——Sodium oxide content, %
Loss on ignition: Loss on ignition (or gain on burning) expressed as a percentage by mass. 9.2 Calculation of aluminum oxide content in chrome corundum The percentage of aluminum oxide in chrome corundum can be calculated by formula (7).(%) = 100 - (wsD, + wr0, + wm,0 + wa,0 + ignition reduction) Where; Ws0, WF,0, wNn,0, ignition reduction - same as (6), Wero
9.3 Permissible error
Permissible deviation shall be in accordance with the provisions of Table 6.
Same laboratory
Different test chambers
Content of chromium trioxide, %,
Determination of sodium trioxide by atomic absorption spectrophotometry 10.1 Method summary
......( 7 )
The sample is melted with anhydrous lithium tetraborate at 1050℃, the melt is leached with salt to prepare a test solution, the absorbance is measured by atomic absorption spectrophotometer, and the result is calculated by standard curve method. 10.2 Reagents
10.2.1 Anhydrous tetraketoacid
10.2.2 Alumina: spectrally pure.
10.2.3 Salt: (15+85).
10.2.4 Chloride: high-purity reagent.
GB 3044-89
10.2.5 Sodium hydroxide standard solution Iodine Weigh 0.3772 g of sodium hydroxide (high-purity reagent) that has been dried at 110°C for 2 h in a 100mL beaker, add water to dissolve, transfer to a 1000mL volumetric flask, dilute to the mark with water, shake well, and set aside (containing 0.2 mg/ml sodium hydroxide). Store in a plastic bottle.
Take 100 mL of the above sodium oxide solution into a 1 000 mL volumetric flask, dilute to the mark, shake well, and this is the sodium oxide standard solution (containing 0.02 mg/mL sodium saccharide). This is stored in a plastic bottle. 10.2.6 Tricapsulated aluminum matrix solution
Weigh 0.2 g of aluminum fluoride (spectrally pure) that has been calcined at 1100°C for 1 h into a platinum glass, add 2 g of anhydrous lithium tetraphosphate and mix, then add 0.5 g, add, slightly open the lid, and place the solution into a high-temperature furnace at 1 050°C to melt for 30 min. Heat the molten material with 80 mL of hydrochloric acid (15+85), dilute, cool, transfer to a 250 mL volumetric flask, dilute to the mark with water, shake well, and store in a plastic bottle for later use. 10.3 Instrument
Atomic absorption spectrophotometer.
10.4 Preparation of standard solution series for determination Take 9 portions of aluminum matrix trihydrate, 25 mL each, and put them into 9 50 mL volumetric flasks respectively. Use micro-liquid measuring tube to add the total volume of the complex solution in turn, mL.
V ~— take the volume of the test solution, mL.
10.B Allowable error
The allowable error shall be as specified in Table 8.
Content
0.51~~1.00
11 Determination of chromium trioxide by atomic absorption spectrophotometry 11.1 Method Summary
GB 3044--89
Allowable error
The sample is melted with anhydrous lithium tetrahydroxide at 1 050°C, and the melt is leached with hydrochloric acid to prepare a test solution. After hexavalent chromium is reduced to trivalent chromium with anhydrous sodium sulfite, the absorbance is measured with an atomic absorption spectrophotometer, and the result is calculated by the standard curve method. 11.2 Reagents
11.2.1 Anhydrous lithium tetrahydroxide.
11.2.2 Alumina, spectrally pure.
11.2.3 Hydrochloric acid: (15+85).
11.2.4 Anhydrous sodium sulfite solution, 2%.
11.2.5 Potassium dichromate: reference reagent,
11.2.6 Chromium trioxide standard solution: weigh 0.0968 g of potassium dichromate (reference reagent) dried at 110°C for 2 h in a 100 mL beaker, add water to dissolve, transfer to a 1000 mL volumetric flask, add water to dilute to the mark, and add water to obtain the chromium trioxide standard solution (containing 0.05 mg/mL chromium trioxide).
11.2.7 Aluminum trioxide matrix solution: see 10.2.6. 11.3 Instruments
Atomic absorption spectrophotometer.
11.4 Preparation of standard solution series for determination Take 8 portions of aluminum oxide matrix solution, 25 mL each, and put them into 8 50 mL volumetric flasks respectively. Use a microburette to add 0.00, 1.20, 2.00, 2.80, 3.60, 4.40, 5.20, 6.00 mL of chromium oxide standard solution in sequence, and add 2 mL of sodium sulfite solution (2%). Dilute with water to the scale and shake well.
11.5 Instrument determination conditions
Instrument determination conditions are shown in Table 9.
Radiation source
Hollow cathode lamp
Wavelength, A
Channel, mm
Note: The current of the hollow cathode lamp is adjusted according to the working current specified at the factory. 11.6 Analysis steps
Flame type
Air-acetylene
Flame state
Stoichiometric flame
Weigh 0.200 0 g of the sample into a platinum crucible, add 2% anhydrous lithium tetraborate, mix well, add 0.5 g, cover, slightly open the cover, send the crucible into a high-temperature furnace at 1050℃ to melt for 30 minutes, heat the molten material with 80mL of 15+85 acid, cool it, transfer it into a 250mL volumetric flask, dilute it to the scale with water, shake it well, take 25mL of the test solution into a 50mL volumetric flask, add 2mL of anhydrous sodium sulfite solution (2%), dilute it to the scale with water, shake it well, and do a blank test at the same time. GB 3044-89
Adjust the instrument according to the selected instrument working conditions. After the hollow cathode lamp is preheated for 20 minutes, the flame is ignited. After normal combustion, the air and acetone flow rates are adjusted, water is sprayed, the zero point is adjusted, and then the standard solution series and the test solution are sprayed, and the corresponding absorbance is read. Repeat the measurement with the same solution, and the absorbance-concentration standard curve is drawn by measuring the average absorbance of the standard solution and the standard solution concentration series. According to the difference between the absorbance of the test solution and the absorbance of the blank, the amount of chromium trioxide in the test solution can be directly found on the standard curve. 11.7 Calculation of analysis results
The percentage of chromium trioxide is calculated according to formula (9): Cr,0,(%) =
In the formula, m1—the amount of chromium trioxide found from the standard curve·g, —the weight of the sample + 81
V—the total volume of the test solution, mL,
V1—the volume of the test solution taken, mL
11.8 Allowable error
The allowable error shall be in accordance with the provisions of Table 10.
Content range
0. 51 ~1. 50
Additional notes:
Allowable error
This standard is drafted by the Zhengzhou Abrasives and Grinding Research Institute of the Ministry of Machinery and Electronics Industry. (9)Transfer to a 250 mL volumetric flask and dilute to the mark with water, shake well, and store in a plastic bottle for later use. 10.3 Instrument
Atomic absorption spectrophotometer.
10.4 Preparation of standard solution series for determination Take 9 portions of aluminum trioxide matrix, 25 mL each, and put them into 9 50 mL volumetric flasks. Use a micro-liquid titration tube to add the compounded sample weight g +
V total test solution volume, mL,
V ~— take the test solution volume, mL.
10.B Allowable error
The allowable error is specified in Table 8.
Content
0.51~~1.00
11 Determination of chromium trioxide by atomic absorption spectrophotometry 11.1 Method Summary
GB 3044--89
Allowable error
The sample is melted with anhydrous lithium tetrahydroxide at 1 050°C, and the melt is leached with hydrochloric acid to prepare a test solution. After hexavalent chromium is reduced to trivalent chromium with anhydrous sodium sulfite, the absorbance is measured with an atomic absorption spectrophotometer, and the result is calculated by the standard curve method. 11.2 Reagents
11.2.1 Anhydrous lithium tetrahydroxide.
11.2.2 Alumina, spectrally pure.
11.2.3 Hydrochloric acid: (15+85).
11.2.4 Anhydrous sodium sulfite solution, 2%.
11.2.5 Potassium dichromate: reference reagent,
11.2.6 Chromium trioxide standard solution: weigh 0.0968 g of potassium dichromate (reference reagent) dried at 110°C for 2 h in a 100 mL beaker, add water to dissolve, transfer to a 1000 mL volumetric flask, add water to dilute to the mark, and add water to obtain the chromium trioxide standard solution (containing 0.05 mg/mL chromium trioxide).
11.2.7 Aluminum trioxide matrix solution: see 10.2.6. 11.3 Instruments
Atomic absorption spectrophotometer.
11.4 Preparation of standard solution series for determination Take 8 portions of aluminum oxide matrix solution, 25 mL each, and put them into 8 50 mL volumetric flasks respectively. Use a microburette to add 0.00, 1.20, 2.00, 2.80, 3.60, 4.40, 5.20, 6.00 mL of chromium oxide standard solution in sequence, and add 2 mL of sodium sulfite solution (2%). Dilute with water to the scale and shake well.
11.5 Instrument determination conditions
Instrument determination conditions are shown in Table 9.
Radiation source
Hollow cathode lamp
Wavelength, A
Channel, mm
Note: The current of the hollow cathode lamp is adjusted according to the working current specified at the factory. 11.6 Analysis steps
Flame type
Air-acetylene
Flame state
Stoichiometric flame
Weigh 0.200 0 g of the sample into a platinum crucible, add 2% anhydrous lithium tetraborate, mix well, add 0.5 g, cover, slightly open the cover, send the crucible into a high-temperature furnace at 1050℃ to melt for 30 minutes, heat the molten material with 80mL of 15+85 acid, cool it, transfer it into a 250mL volumetric flask, dilute it to the scale with water, shake it well, take 25mL of the test solution into a 50mL volumetric flask, add 2mL of anhydrous sodium sulfite solution (2%), dilute it to the scale with water, shake it well, and do a blank test at the same time. GB 3044-89
Adjust the instrument according to the selected instrument working conditions. After the hollow cathode lamp is preheated for 20 minutes, the flame is ignited. After normal combustion, the air and acetone flow rates are adjusted, water is sprayed, the zero point is adjusted, and then the standard solution series and the test solution are sprayed, and the corresponding absorbance is read. Repeat the measurement with the same solution, and the absorbance-concentration standard curve is drawn by measuring the average absorbance of the standard solution and the standard solution concentration series. According to the difference between the absorbance of the test solution and the absorbance of the blank, the amount of chromium trioxide in the test solution can be directly found on the standard curve. 11.7 Calculation of analysis results
The percentage of chromium trioxide is calculated according to formula (9): Cr,0,(%) =
In the formula, m1—the amount of chromium trioxide found from the standard curve·g, —the weight of the sample + 81
V—the total volume of the test solution, mL,
V1—the volume of the test solution taken, mL www.bzxz.net
11.8 Allowable error
The allowable error shall be in accordance with the provisions of Table 10.
Content range
0. 51 ~1. 50
Additional notes:
Allowable error
This standard is drafted by the Zhengzhou Abrasives and Grinding Research Institute of the Ministry of Machinery and Electronics Industry. (9)Transfer to a 250 mL volumetric flask and dilute to the mark with water, shake well, and store in a plastic bottle for later use. 10.3 Instrument
Atomic absorption spectrophotometer.
10.4 Preparation of standard solution series for determination Take 9 portions of aluminum trioxide matrix, 25 mL each, and put them into 9 50 mL volumetric flasks. Use a micro-liquid titration tube to add the compounded sample weight g +
V total test solution volume, mL,
V ~— take the test solution volume, mL.
10.B Allowable error
The allowable error is specified in Table 8.
Content
0.51~~1.00
11 Determination of chromium trioxide by atomic absorption spectrophotometry 11.1 Method Summary
GB 3044--89
Allowable error
The sample is melted with anhydrous lithium tetrahydroxide at 1 050°C, and the melt is leached with hydrochloric acid to prepare a test solution. After hexavalent chromium is reduced to trivalent chromium with anhydrous sodium sulfite, the absorbance is measured with an atomic absorption spectrophotometer, and the result is calculated by the standard curve method. 11.2 Reagents
11.2.1 Anhydrous lithium tetrahydroxide.
11.2.2 Alumina, spectrally pure.
11.2.3 Hydrochloric acid: (15+85).
11.2.4 Anhydrous sodium sulfite solution, 2%.
11.2.5 Potassium dichromate: reference reagent,
11.2.6 Chromium trioxide standard solution: weigh 0.0968 g of potassium dichromate (reference reagent) dried at 110°C for 2 h in a 100 mL beaker, add water to dissolve, transfer to a 1000 mL volumetric flask, add water to dilute to the mark, and add water to obtain the chromium trioxide standard solution (containing 0.05 mg/mL chromium trioxide).
11.2.7 Aluminum trioxide matrix solution: see 10.2.6. 11.3 Instruments
Atomic absorption spectrophotometer.
11.4 Preparation of standard solution series for determination Take 8 portions of aluminum oxide matrix solution, 25 mL each, and put them into 8 50 mL volumetric flasks respectively. Use a microburette to add 0.00, 1.20, 2.00, 2.80, 3.60, 4.40, 5.20, 6.00 mL of chromium oxide standard solution in sequence, and add 2 mL of sodium sulfite solution (2%). Dilute with water to the scale and shake well.
11.5 Instrument determination conditions
Instrument determination conditions are shown in Table 9.
Radiation source
Hollow cathode lamp
Wavelength, A
Channel, mm
Note: The current of the hollow cathode lamp is adjusted according to the working current specified at the factory. 11.6 Analysis steps
Flame type
Air-acetylene
Flame state
Stoichiometric flame
Weigh 0.200 0 g of the sample into a platinum crucible, add 2% anhydrous lithium tetraborate, mix well, add 0.5 g, cover, slightly open the cover, send the crucible into a high-temperature furnace at 1050℃ to melt for 30 minutes, heat the molten material with 80mL of 15+85 acid, cool it, transfer it into a 250mL volumetric flask, dilute it to the scale with water, shake it well, take 25mL of the test solution into a 50mL volumetric flask, add 2mL of anhydrous sodium sulfite solution (2%), dilute it to the scale with water, shake it well, and do a blank test at the same time. GB 3044-89
Adjust the instrument according to the selected instrument working conditions. After the hollow cathode lamp is preheated for 20 minutes, the flame is ignited. After normal combustion, the air and acetone flow rates are adjusted, water is sprayed, the zero point is adjusted, and then the standard solution series and the test solution are sprayed, and the corresponding absorbance is read. Repeat the measurement with the same solution, and the absorbance-concentration standard curve is drawn by measuring the average absorbance of the standard solution and the standard solution concentration series. According to the difference between the absorbance of the test solution and the absorbance of the blank, the amount of chromium trioxide in the test solution can be directly found on the standard curve. 11.7 Calculation of analysis results
The percentage of chromium trioxide is calculated according to formula (9): Cr,0,(%) =
In the formula, m1—the amount of chromium trioxide found from the standard curve·g, —the weight of the sample + 81
V—the total volume of the test solution, mL,
V1—the volume of the test solution taken, mL
11.8 Allowable error
The allowable error shall be in accordance with the provisions of Table 10.
Content range
0. 51 ~1. 50
Additional notes:
Allowable error
This standard is drafted by the Zhengzhou Abrasives and Grinding Research Institute of the Ministry of Machinery and Electronics Industry. (9)(%) =
Wherein, m1—the amount of chromium trioxide obtained from the standard curve·g, —the weight of the sample + 81
V—the total volume of the test solution, mL,
V1—the volume of the test solution taken, mL
11.8Allowable error
Allowable error shall be in accordance with the provisions of Table 10.
Content range
0. 51 ~1. 50
Additional instructions:
Allowable error
This standard is drafted by the Zhengzhou Abrasives and Grinding Research Institute of the Ministry of Machinery and Electronics Industry. (9)(%) =
Wherein, m1—the amount of chromium trioxide obtained from the standard curve·g, —the weight of the sample + 81
V—the total volume of the test solution, mL,
V1—the volume of the test solution taken, mL
11.8Allowable error
Allowable error shall be in accordance with the provisions of Table 10.
Content range
0. 51 ~1. 50
Additional instructions:
Allowable error
This standard is drafted by the Zhengzhou Abrasives and Grinding Research Institute of the Ministry of Machinery and Electronics Industry. (9)
Tip: This standard content only shows part of the intercepted content of the complete standard. If you need the complete standard, please go to the top to download the complete standard document for free.