Some standard content:
JB/T 79971999
This standard is a revision of JB/T7997-95 (formerly GB11267-89) "Chemical Analysis Methods for Lithium and Phosphate".
This standard is consistent with the technical content of JB/T7997-95, and has only been re-edited according to relevant regulations. This standard replaces JB/T7997-95 from the date of implementation. This standard is proposed and managed by the National Technical Committee for Standardization of Single-release Instruments. The drafting unit of this standard: Zhengzhou Moke Instrument Research Institute. The main drafters of this standard are Wen Wu and Ji Suoju. 287
Standard of the Machinery Industry of the People's Republic of China
Garnet
Chemical Analysis Method
JB/T 7997—1999
Substituted for JB/T 2997-95
This standard specifies the determination method of silicon dichloride, aluminum trichloride, iron trioxide, titanium dichloride, iron oxide, calcium oxide, magnesium oxide and oxide chain in garnet.
This standard is applicable to the determination of chemical composition of garnet and block garnet. 2 Reference Standards
The provisions contained in the following references are referenced in this standard or are provisions of this standard. When this standard is published, the versions shown are valid. All standards will be revised. The parties using this standard should discuss the possibility of reverting to the latest version of the following standards. GB/T 4676-1984
Methods for extracting the same sample
General provisions
3.1 When performing secondary analysis, the average number of copies of the same sample shall not be less than three copies. If the difference in the analysis results is within the allowable range, the arithmetic mean shall be taken as the final analysis result.
3.2 Except for special specifications, analytical reagents shall not be less than analytical purity. For reference, reference trial production or high-purity reagents shall be used. 3.3 Except for the reagents specified, the reagents contained are all aqueous solutions. 3.4 Liquid reagents without concentrations specified are all surface solvents, such as acetic acid (relative density 1.19) and ammonia water (relative density 0.90). Unspecified solid reagents, such as sodium carbonate, refer to the original reagents. 3.5 The percentage of reduction refers to the number of grams of solute contained in 100 mL of solution. (1+1), 1+2)-*.(m+^) etc. refer to the ratio of the volume of the solute to the volume of water
3.6 Unless otherwise specified, distilled water or deionized water is used for preparing reagents and analyzing water. 3.7 The sensitivity of the analytical balance used, except for the fast one, should reach 0.1 mg. The analytical balance, carbon code and volumetric device must be calibrated. 38 All operations, unless otherwise specified, are carried out in a glassware set. 39 The "burn to constant weight" mentioned above means that after two consecutive burns and cooling to empty in the medium, the difference between the two weighings does not exceed 0.2 mg
3.10 The number of "thousand passes" refers to the number of drops of water used for the test paper and the dry funnel, which are passed through the dry container. The toughest filtrate should be discarded when the test sample is passed through the dry container. 3.11 Sample sampling shall be in accordance with GB/T4676.
3.12 For samples coarser than No. 100 particle size, first use a factor to divide it into 15~20g, then use a test mortar to grind it until the rest passes through a 150um sieve (for samples with a fast measurement of chemical properties, it should pass through an 80m sieve), mix them evenly, and put them into the sample container. For samples with a particle size of No. 100, use the quartering method to divide them into 2 0g+ is put into the sample bag and immediately placed in a desiccator for use. Determination of dichloromethane
4.1 Method
Test group Use sand-carbonic acid to decompose the melt, remove it with hydrochloric acid, evaporate it to the desalted state, add mortar to make the silica gel condense, burn it to constant weight, treat it with hydronitric acid and sulfuric acid to make the silicon escape as tetroxide, and then burn it to constant weight. The difference between the weight and the weight after the hydrochloric acid treatment is approved by the State Machinery Industry Bureau on May 20, 1999 288
2000-01-07
JB/T 7997—1999
is silicon dichloride, and the residual silicon dioxide in the filtrate is determined by silicon phase drive spectrophotometry. Adding it to the former, the content of silicon dioxide in the sample is obtained.
4.2 Reagents
4.2.1 Original-carboxylic acid mixed flux: (1+1). Weigh one part of Xinjiang sand and one part of sodium carbonate in agate mortar, grind them finely, mix them and store them in a wide-mouth bottle. 4.2.2 Hydrochloric acid, (20+80).
4.2.3 Ammonium salicyclic acid solution 5%.
4-2.4 Para-nitrobenzene with indicator 0.2% ethanol drop liquid, 4.2.5 or ferrous ammonium solution: 6%.Www.bzxZ.net
4.2.6 Grass Sulfur mixed acid solution: (1+1)
Measure one part of (5%) oxalic acid and one part of (3+3) oxalic acid and mix them evenly. 4.2.7=Silicon dioxide standard culture solution: 1ml. Contains 0.03mg of silicon dioxide. Weigh 0.3000g of silicon dioxide (high-ton reagent) burned at 1000C in a crucible, add 3g of anhydrous sodium carbonate (standard reagent) and mix, put the whole into a high-temperature furnace and melt at 850~900C for 20~30min, take it out, extract it with hot water, cool it, transfer it to a 1000ml volumetric flask, dilute it to the scale with water, shake it evenly, and immediately transfer it to a plastic bottle that has been cleaned and deionized in advance, store it, this liquid 1mL Contains 0.3mg of silicon dioxide.
Take 100mL of the above silicon dioxide in a 1000mL volumetric flask, neutralize with (5+95) sulfuric acid solution to slightly acidic, dilute with water to scale, mix well, and it is the silicon dioxide standard solution, 1ml. Contains 0.03mg of silicon dioxide. 4.2.8 Blank solution
Weigh 4g of mixed flux in a flask, melt in a 1000C high temperature furnace for 10min, take out, cool, heat and extract with 100mL of (20+80) acid solution, transfer to a 250mL volumetric flask, cool, dilute with water to scale, and mix well.4.3 Drawing of working solution
Take eight portions of blank solution Take 5 mL of each and put them into 100 mL volumetric bottles respectively. Use a volumetric tube to add 0.00, 0.50, 1.00, 2.00, 4.00, 6.00, 8.00, 10.00 ml of silica standard solution (0.03 mg/mL), 10 ml of water, and 5 mL of 5% sodium chloride solution in sequence. After mixing well, let it stand for 10-15 min. While stirring, add 20 mL of (1 + 1) tricresyl ether. Rapidly add 5 mL of 6% ferrous chloride, dilute with water to the scale, mix well, use water as a reference, and measure the absorbance at a wavelength of 690 nm on a spectrophotometer using a 1 cm colorimeter. Remove the blank value and verify the working curve. 4.4
Analysis steps
Weigh 0.5000g of the unbaked sample in a platinum case, add 3g of mixed flux, mix well, and then cover with 1g. Place it in a high-temperature furnace, raise it from low humidity to 950~1000C to melt for 1~1.5h. Take it out, turn it over to make the molten material adhere to the surface of the sample, cool it down, put it in a beaker with 100mL of nearly boiling (20+80) acid, heat it on a simmer, draw it out, wash it with water, and place the beaker on a sand trap to evaporate it until it is free of salt. When the mixture is in a state of being molten, add 0.1g of animal glue tablets, stir thoroughly for 2-3min, keep warm in a water trap at 60-70℃ for 20min, remove, add 40mL of (5+95) hot hydrochloric acid, stir to dissolve, filter with medium-speed quantitative filter paper, wash with hot (5+95) hydrochloric acid 7-8 times, then wash with water until there is no chloride, filter into a 250mL volumetric flask, cool, dilute with water to 300℃, and keep the flask for determination of aluminum oxide, calcium oxide, and magnesium oxide. Put the filter paper in a platinum crucible, carefully dry and ash it, move it into a high-temperature furnace, burn it at 980-1000℃ for 1h, take it out, cool it, put it in a desiccator, cool it to the empty group and weigh it to constant weight. The precipitate after burning is moistened with water, add 1-2 molten sulfuric acid, add 5ml of hydrochloric acid, put it on the sand, evaporate it, white smoke of acid is emitted, take it out, cool it, add 2-3mL of hydrochloric acid, continue to evaporate to dryness, put it in a high humidity container, and keep it at 980-1000℃ for 15-30min, take it out, cool it Weigh until it is stable.
Take 5 ml of the silica filtrate. Add 40 ml of water to a 100 ml measuring cup, add 2 drops of 0.2% p-nitropropene indicator, neutralize with ammonia water until the color is dark, immediately add 5 ml of (1+4) hydrochloric acid, add 5 ml of ammonium sulfate, and stand for 10-15 minutes. The following procedures are as described in 4.3. Find out the milligrams of silica.
Calculation of analysis results
Calculate the percentage content of silica w(SiO2) according to formula (1) =
JB/T 7997—1999
Wherein: m--precipitate and exhaust mass before hydrofluoric acid treatment + g:m; ---residue and increased exhaust mass after hydrofluoric acid treatment·g:m——test sample mass·g:
C---silicon dioxide content obtained from the standard curve, mg. 4.6 Allowable error
The allowable error is determined according to Table 1,
Content range
>5. 00~10.00
≥> 10. 00~20. 00
>20, 00 ~~ 50, 00
5 Determination of aluminum trichloride
5.1 Methods
Same laboratory
Different laboratory
±0 40
.-( 1)
In a strong terminal solution, the corresponding hydroxide is generated, and aluminum enters the liquid in the form of sodium aluminate. After filtration, the aluminum is removed by the drum.
Add excess EDTA to the test solution to form an AI-EDTA complex. The excess EDTA is determined by the standard wave of zinc sulfate. The content of aluminum trioxide is calculated based on the number of milliliters of EDTA standard source consumed. 5.2 Reagents
Sodium hydroxide solution: 505%.
5.2.2 Salt glue: (1+1),
5.2.3 Methylamine indicator: 0.05%,
5.2.4 Methylenetetramine: 15%.
5.2.5 Xylenol indicator: 0.5%
5.2.6 EDTA standard density: 0.05M, weigh EDTA18.61g in a 400mL beaker, add 200mL water. Heat to dissolve, cool and pour into a 1000ml volumetric flask, dilute to the desired concentration with water, and add 1% water to dissolve. Calibration: Weigh 1.7848g of calcium carbonate (standard reagent) dried at 110°C for 2h in a 250mL beaker, add 50mL of water, add (1+1) hydrochloric acid until completely dissolved and add 2~3 drops in excess, heat to remove the hydrogen dioxide, cool and transfer to a 1000mL volumetric flask, dilute to scale with water, shake, this calcium oxide standard solution contains 1.00mg of calcium oxide per milliliter. Transfer 80mL of this calcium oxide standard solution to a 300mL flask, add 100mL of water and 10mL of 20% sodium hydroxide solution. Shake, add a small amount of calcium reagent sodium salt indicator, and titrate with the prepared EDTA standard solution until pure blue is the end point. And short the test stock under the same conditions,
Calculate the formula (2):
JB/T 7997-1999
Wherein, m-monochloridized mass + g:
V--the total volume of EDTA standard solution consumed at the time of elimination.mL (deducted by the case value): Ta--the titer of EDTA standard solution to calcium oxide.g/mL. Zinc iodide standard (0.025M). Weigh 7.2g of zinc iodide in 250mL standard solution, add 100mL of water and stir to dissolve, add 5.2.7
(1+1) solution until it is clear, transfer it to a 1000mL volumetric flask, dilute to the required weight with water, mix well, and set aside. Calibration: Take 10mL of 0.05M EDTA standard solution from the standard solution and put it in a 250mL flask. Add 50mL of water and 5mL of 15% methenyl tetrahydrofuran solution. Add dimethylformamide as the indicator. Titrate the prepared zinc chloride standard solution until the color changes from yellow to constant red.
Calculate according to formula (3);
Where: K---the volume of zinc chloride standard solution consumed by 1mL EDTA standard solution, ml.: V,--the total volume of zinc carbonate standard solution consumed during the elimination period, ml. Calculate the titer of EDTA standard solution against lead oxide according to formula (4): Tag,
Where: Tsya,
Ten × 0.909 1
Titer of zinc chloride standard solution against sodium trioxide, g/ml; Titer of EDTA standard solution against calcium oxide - g/mL; 0.9091 - coefficient for conversion of calcium chloride into aluminum trifluoride; -1 mL of EDTA standard solution is equivalent to the volume of zinc murine acid standard solution, K-
5.3 Analysis step Black
Take 50 ml of the filtrate after separation of silicon dichloride in 4.4 and In a 250mL beaker, dilute to 100mL with water, add 50% sodium hydroxide solution until a large amount of precipitation occurs, then add 10mL, heat the test solution to 40-60°C and keep it moist for 30 minutes. Remove the beaker, cool to room temperature, transfer to a 250mL volume, dilute to the mark with water, shake, and place until the precipitate sinks, then filter at medium speed into a dry beaker, drain the precipitate in half and add (1+1 ) hot hydrochloric acid is dissolved in the original beaker, and then washed with (5495) hot hydrochloric acid until there is no yellow color, and washed with hot water 8 to 10 times. This increase in liquid retention is used to determine the aluminum trioxide, and the sugar solution is used for aluminum trioxide. Take 100mL of the above-mentioned lacking liquid in a 250ml chain bottle, add methyl lattice indicator 1, and use (1+1) to adjust the color until it is stable red, and add 2 drops in excess. Add 15ml of 0.05MEDTA standard drop solution. Blow the bottle with water. For example, heat and boil for 3 minutes. Cool to room temperature with running water, add 10 ml of 15% hexamethylenetetramine and 1 ml of 0.5% dimethyl phthalate as an indicator, and use 0.025M sulfuric acid standard solution to eliminate until the color changes from yellow to red.
5.4 Calculation of analytical results
Calculate the percentage of aluminum oxide according to formula (5): (VV,)×Tu×100%
e(Al,O,)
Wherein: V, the volume of EDTA standard solution added, ml; V~-the volume of zinc sulfate standard solution consumed during titration, mL] mL. EDTA standard solution is equivalent to the volume of potassium trioxide standard solution, mL; K-
TAo,---the concentration of potassium trioxide in zinc sulfate standard solution. g/mL; w-the mass of the sample to be tested.
5.5 Allowable error
The allowable error shall be in accordance with the provisions of Table 2.
Appropriate range
>70,00 ~20,00
>2n,00~30,00
6 Determination of ferric oxide
6.1 Summary of the method
JB/T 7997--1999
Same as the test
Unadjusted
In salt medium, use rust reduction to generate divalent iron ions, use rust reduction to obtain the excess amount of ferrous metal, use sulfonic acid as indicator, use potassium dichromate standard to determine: valence loss, 6.2 Test
6.2.1 Acid (1+1)
6.2.2 Hydroxyacetic acid-phosphoric acid decomposition solution, measure 150ml of sulphuric acid and slowly inject it into 700ml of water, add 150ml of alcohol acid.. Select and set aside
Dihydrogenation solution: 10%, 1% 0g dichloromethane is heated in 2)ml hydrochloric acid. Dilute with water to 100ml. Sentence: 6.2.3
6.2.4 Oxidizing agent, 5%, weigh 5g of fluoride and drop it into 100ml hot water. After cooling, take the supernatant for use. 6.2.5
Diphenylmethane fluoride solvent: 41.5%
Standard potassium dichromate, 0.05N, accurately take 2g of potassium dichromate (standard trial production>2.4517) dried at 150C and put it in 6.2.6
250ml. beaker, add water to dissolve, then transfer to 1000mL volumetric flask and dilute with water to the desired concentration. Prepare according to the preparation period. 6.3 Analysis step
Add about 30mL of the test fluid in the beaker prepared in 5.3, add dichloromethane dropwise by differential thermal until the yellow color disappears, then add 1-2 drops more, cool to room temperature with water, quickly add 15mL of dichloromethane solution, fully absorb and stand for 3-5min, add 50ml of water and add 10mL of mineral acid, add 2-3mL of diphenylamine as an indicator, and filter and determine with heavy acid standard until a stable blue color is observed, which is the end point.
6.4 Analysis and calculation
Calculate the white content of ferric oxide according to formula (6): NV × 0. 079.85 × 100% e(Fe0) × 1.111 3w(Fe,O.) =
Wherein: N-
equivalent concentration of potassium dichloride standard solution: V---volume of the standard solution of dichloride consumed.mL; 0.07985--3mg equivalent of ferric chloride: test sample mass·R:
1.1113-·oxidation amount iron conversion factor or ferrous oxide coefficient, 6.5 allowable error
allowable error is determined in Table 3,
total amount model
>5, n0~10. 60
>Ic, op -- gn. un
Calcium chloride determination
degradation test
different European test
ta, 15
7.1. According to the principle of separation, hexamethylenetetramine was used to separate iron, titanium and other elements. When the pH was 8-13, calcium ions could complex with a certain amount of EDTA. When the pH was ≥12, a small amount of magnesium ion formed Mg(OH)- or Mg(OH)-, which precipitated and did not interfere with the determination. At this time, calcium ions reacted with calcium to form a red complex, but calcium ions could form a more solid complex with RDTA. When the EDTA complex was titrated, calcium ions were taken away from it and calcium reagent was released. When the solution showed red color, it was the end point. The calcium oxide content was calculated from the amount of EDTA standard solution consumed. The reaction formula is as follows:
Ca\'+H, Y!
---CaY -2H
Ca--HInd-Calnd
Pure blue
Calnd-+H,Y\-
Red
7.2 Reagents
Hexamethylenetetramine: 15%.
Caindium oxide: 20%.
Cainium test plate indicator: (1+100) Purple
+Ca Y\
-Hlrd +H
Pure monstrous
Take 0.5g of sodium carboxylate prepared by calcium and mix it with 50g of sodium oxide. FDTA gradient: 0.01M
Weigh 3.75g of EIYTA into a 400ml beaker, add 20ml of water, heat under low temperature to decompose. After cooling, filter into a 1001ml volumetric medium, and use water to decompose the dust. Calibration: Accurately weigh 1.7848g of calcium oxide (standard reagent) that has been baked for 2 hours at 110°C into a 250ml cup, add 51ml of water, add (1+1) sodium chloride until completely dissolved, and add 2-3 drops in excess, heat and boil, remove the dioxide, cool, transfer to a 1000ml container, dilute with water to the desired concentration, and stir. This solution is the calcium oxide standard solution. 1ml contains 1.00mg of calcium oxide. Transfer 10ml of calcium oxide standard solution to a 300ml conical flask. Add [00ml] of water. Add 10ml of 20% oxygen and stir for 2-3min, add a small amount of sodium calcium oxide pad indicator, and titrate with a 0.01METTA standard solution prepared with pancreas until pure blue is the end point. Under the condition of phase separation, the self-test
is calculated according to formula (7). Formula (8):
7mei = Tea. X 0. 718 8
Wherein: G.-mass of calcium hydroxide·g;
volume of EDTA standard solution consumed at full time, mL: V
titer of EDTA standard solution for magnesium oxide -g/mL: titer of EDTA standard solution for magnesium oxide +g/mL: coefficient for converting (Ca) into MgO.
7.3 Preparation of analytical test solution
Pipette 50 ml of silicon dioxide solution (see 4.4) into a 250 ml beaker, add 80 ml of water, dissolve with 20% sodium hydroxide until a precipitate forms, then add (1+1) acetic acid until the precipitate dissolves, add 5 ml of 15% hexamethylenetetramine, heat until a precipitate forms, cool, add 0.3 g of test solution, place for more than 1 hour, and place in a 250 ml volumetric flask, rinse 8-10 times with 2% hexamethylenetetramine, and shake well with water to the scale. This solution is used for 7.4 Analysis steps for determination of CaO and MgO Transfer 100 ml of the analytical test tube (7.3) to a 300 ml chain bottle, add 20 ml of 20% sodium hydride. Let stand for 5-14 min, add a small amount of calcium reagent as the acid-limited sodium salt indicator, and titrate with (.01 M EDTA standard solution until pure color is obtained as the end point, and perform a whitening test under the same conditions.
7.5 Calculation of analysis results
Calculate the content of calcium oxide using formula (9)
B/T 7997 1999
w(CaO)
Wherein: V--the volume of 0.01MEDTA standard solution consumed for determination (E minus blank solution), ml.: 7--the titer of FDTA standard solution for calcium oxide + g/ml:-the amount of the test sample.
7.6 Allowable error
The allowable error is as specified in Table 4
Quantity range
>1. 0~-3. 00
>3. 00~5. 00
>5. 00 ~ 30, 00
Determination of magnesium oxide
8.1 Summary of the method
Same--Laboratory
±n, 30
Different test rates
± 0 18
±0, 33
Use hexamethylenetetramine-sodium reagent to separate iron, titanium, zirconium, and other elements. According to the principle that the ions can be quantitatively complexed with EITA in the presence of ions, this method is used at pH 10, and the magnesium and calcium ions in the test solution form a purple-red final complex with EDTA. Titrate with EITA standard solution, and the ammonium and calcium ions form a certain amount of non-complex with EDTA, and the EDTA is separated from the monohydrate. When the droplet turns red, it is the end point. The amount of EDTA standard dissolved minus the amount of EDTA standard dissolved during the titration is used to obtain the magnesium oxide content. Its reverse formula is as follows:
+MgY*-+2H*
Mg**+H,Y*
Mg\- +HInd--_.--Mglnd +H
Mgind +1,Y*- . +MgY*- +HInd? -+H Purple red package
8.2 Reagents
8.2.1 Hexamethylenetetramine 15%,
8-2.2 Copper reagent,
82.3 Chloride black T indicator: (1+100).
Weigh 0.5g of Chloride black T and 50g of sodium fluoride, mix well. B-2.4 EDTA standard solution: 0.01M (see 7.&.5). B.2.5 Ammonium chloride-ammonia hydroxide solution: pH 10 Pure blue
Weigh 67.50g of ammonium chloride and put it into 250mL of water, add 570mL of ammonium hydroxide, dilute to 1000ml with rice and mix well. 8.3 Step 1: Pipette 100 mL of the analytical solution (see 7.3) into a 300 mL vial, add 10 mL of ammonium fluoride-hydroxide buffer solution with a pH of 10 and a small amount of a sodium chromate indicator. Titrate with 0.01 M EDTA standard solution until a blue color appears, which is the end point. This is the calcium and magnesium content. Perform a blank test under the same conditions. 8-4 Calculation of analysis results
Calculate the content of magnesium oxide according to formula (10):
Mg0) = 2 × 110%
-+--+--*( 10 )
JB/T 7997—1999
Wherein, the titration degree of ToEDTA standard solution on magnesium oxide·g/nL: V.
The volume of 0.01MEDTA standard solution consumed during titration (the blank value has been subtracted).ml; V:————The volume of 0.01MEDTA standard roll consumed during calcium titration (the white value has been subtracted).mL: The mass of the sample being tested·g
Allowable error
Allowable error shall be in accordance with the provisions of Table 5,
The content range
>1. 00~3. 00
>3. 00~5. 00
>5. 00~ 10. 00
Determination of iron dioxide
one laboratory
different testers
Method Summary
In an acidic medium with a pH of 1.2~3.5, tetravalent titanium reacts with hydrogen perchloride to form a yellow complex, and the absorbance of the colored liquid is measured at a length of 420~4%0mm.
The ferric iron is oxidized by the colorimetric method. When determining the absorbance of the complex, the sample blank (not as hydrogen peroxide) is used as the reference liquid to eliminate the iron. In order to make all the divalent iron in the solution in the trivalent form, a small amount of sodium nitrite is added to oxidize it. 9.2 Reagents
Solvent: one part of anhydrous sodium nitrate and two parts of ketone sand. 9.2.2
Acid: (10+90),
Acid: (1+3).
Standard reagent for divalent iron.
Sulfuric acid.
Hydrogen peroxide: 3%, (10% by weight of hydrogen peroxide dissolved in water). Sodium nitrite solution: 3%.
Titanium dioxide standard liquid: weigh 0.2500g of titanium dioxide (standard reagent) burned at 980-1000℃ for 1h in a 300mL beaker, add 20mL of ammonium sulfate and 30mL of sulfur solution, cover with blood.Heat on a wire electric furnace until completely dissolved. After completely cooling, pour into another 400mL volumetric standard containing 250mL water in advance under stirring. After cooling, transfer to a 1000mL volumetric flask. Select two porcelain cups, wash and combine, and add them to a 1000mL volumetric flask. Dilute with water to the mark. This standard solution contains 0.25 rmg of dichloromethane per liter. 9.2.9 Blank solution: Take 2g of the filtered flux and melt it in a high-temperature furnace at 950C for 20min. Take it out, cool, wash and add 100mL of (10+90) quartz acid to heat slowly, transfer to a 250mL volumetric flask, cool, dilute with water to the mark, add water and set aside. 9.3 Drawing of working curve
Take six portions of 25 mL of blank solution and put them into six 50 mL volumetric flasks respectively. Use a micro-pipet to add 0.00, 0.20, 0.50, 1.00, 2.00, 3.00 mL of titanium dioxide standard solution in sequence (i.e. the percentage of titanium dichloride is 0.00, 0.20, 0.50, 1.00, 2.00, 3.00). Add 10 mL of (1+3) silica, 5 mL of 3% hydrogen peroxide, dilute to the scale with water, and measure its absorbance at a wavelength of 420 nm on a colorimeter with 1 cm colorimetric precision and the reagent blank as a reference to prepare the working curve. 9.4 Analysis steps
Weigh 0.25g of unbaked sample in a monohydrate solution, add 1.5g of mixed flux, mix well, add 0.5g of mixed flux, put into a high temperature furnace, heat at 9501000C for 1h, take out, transfer to a heating machine to make the baked product adhere to the heating chamber, cool, wash and condense on the glass, several people have 235
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