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GB 25582-2010: National food safety standards of food additives calcium silicate aluminum
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National food safety standards of food additives calcium silicate aluminum
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GB 25582-2010
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Basic data | Standard ID | GB 25582-2010 (GB25582-2010) | | Description (Translated English) | National food safety standards of food additives calcium silicate aluminum | | Sector / Industry | National Standard | | Classification of Chinese Standard | X40 | | Classification of International Standard | 67.220 | | Word Count Estimation | 13,142 | | Date of Issue | 2010-12-21 | | Date of Implementation | 2011-02-21 | | Regulation (derived from) | Ministry of Health Bulletin No. 19 of 2010 | | Issuing agency(ies) | Ministry of Health of the People's Republic of China | | Summary | This Chinese standard applies to prepared food additive sodium silicate aluminum silicate. | GB 25582-2010: National food safety standards of food additives calcium silicate aluminum---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order.
National food safety standards of food additives calcium silicate aluminum
National Food Safety Standard
Food additives calcium aluminum silicate
Issued on. 2010-12-21
2011-02-21 implementation
National Standards of People's Republic of China
People's Republic of China Ministry of Health issued
Foreword
Appendix A of this standard is a normative appendix.
National Food Safety Standard
Food additives calcium aluminum silicate
1 Scope
This standard applies to food additives calcium aluminum silicate water glass is prepared.
2 Normative references
The standard file referenced in the application of this standard is essential. For dated references, only the edition date of the note
Apply to this standard. For undated references, the latest edition (including any amendments) applies to this standard.
3 molar ratio of components
Al2O3/CaO/SiO2 molar ratio (molar ratio) is approximately 1. 9.12.
4. Technical Requirements
4.1 Sensory requirements. comply with Table 1.
Table 1 Sensory requirements
Project requires test methods
Color white. Take appropriate 50mL sample is placed in a beaker, natural
Light to observe the color and texture. State organization powders or granules
4.2 Physical indicators. to comply with Table 2.
Table 2. Physical and chemical indicators
Item Index Test Method
Silicon dioxide (SiO2), w /% 44.0 ~ 50.0 Appendix A A.4
Aluminum oxide (Al2O3), w /% 3.0 ~ 5.0 A.5 Appendix A
Calcium oxide (CaO), w /% 32.0 ~ 38.0 A.6 in Appendix A
Sodium oxide (Na2O), w /% 0.5 ~ 4.0 A.7 Appendix A
Loss on ignition, w /% 14.0 ~ 18.0 Appendix A A.8
Fluorides (as F)/(mg/kg) ≤ 50 Appendix A A.9
Lead (Pb)/(mg/kg) ≤ 5 Appendix A A.10
Arsenic (As)/(mg/kg) ≤ 3 Appendix A A.11
Heavy metals (Pb)/(mg/kg) ≤ 10 Appendix A A.12
Loss on drying, w /% ≤ 10.0 Appendix A A.13
Appendix A
(Normative)
Testing method
A.1 Warning
The standard test method requires the use of some of the acid, when used, be careful to avoid splashing on the skin! As splashed on the skin should stand
That is rinsed with water, severe cases should be treated immediately. When using a volatile acid, to be carried out in a fume hood.
A.2 General Provisions
The standard test methods used in the reagents and water in the absence of other specified requirements, refer to analytically pure reagents and GB/T 6682-2008 in
Three water regulations. Test with the standard titration solution, impurity standard solution, preparations and products, did not indicate when the other requirements, according
HG/T 3696.1, HG/T 3696.2, the provisions of HG/T 3696.3 of preparation.
A.3 Identification Test
A.3.1 Identification of silicate
The 0.5 g sample is mixed with 2.5 g of anhydrous potassium carbonate, heated on a hot plate in a platinum crucible to melt the mixture, cooled, 5 mL
Water and let stand 3 min, the crucible plus micro heat, add 50 mL of water to dissolve. Completely transferred to a beaker, was added dropwise a solution of hydrochloric acid (11) to airless
Bulbs, add 10 mL of hydrochloric acid, evaporated to dryness on a steam bath to cool. Was added 20 mL of water, filtered boiling, insoluble gel residue
Used to identify silicon. The filtrate was the test solution A, for the identification of aluminum.
The gelatinous residue was taken platinum crucible, carefully add 5 mL of hydrofluoric acid. The precipitate was dissolved. Heating, placed in the vapor above the crucible
A glass rod moistened with a drop of water, the water droplets become cloudy.
A.3.2 Identification of aluminum ions
Was added dropwise in the test solutions A (A.3.1) in aqueous ammonia solution (11), a white gelatinous precipitate, addition of excess aqueous ammonia solution, no precipitate
Dissolved. Was added dropwise a solution of sodium hydroxide (40 g/L) to give a white gelatinous precipitate, the precipitate dissolved when added in excess.
A.3.3 Identification of calcium ions
Take a few samples, hydrochloric acid solution (12) was dissolved phenolphthalein solution (10 g/L) as the indicator solution, (13) adjusted with ammonia solution
To neutral, the solution was added ammonium acetate (35 g/L) That is, the white precipitate, this precipitate can be dissolved in hydrochloric acid solution (12), but not dissolved in glacial acetic
acid.
A.4 Determination of silica
A.4.1 Method summary
Silica in the sample with hydrofluoric acid forming volatile matter by burning volatile, silica calculated by measuring the difference between the mass before and after burning
Content.
A.4.2 Reagents and materials
A.4.2.1 perchloric acid.
A.4.2.2 hydrochloric acid.
A.4.2.3 sulfuric acid.
A.4.2.4 hydrofluoric acid.
A.4.3 Instruments and Equipment
High-temperature furnace. temperature can be maintained at 900 ℃ ± 25 ℃.
A.4.4 Analysis step
Weigh was 105 ℃ ± 2 ℃ bake a sample of about 0.5 g 2 h, to the nearest 0.0002 g, into a 200 mL beaker with a small amount of water will
Wash the beaker wall. Perchloric acid was added 30 mL and 15 mL hydrochloric acid, in a hood on a hot plate heated until white smoke is generated, added after cooling
15 mL of hydrochloric acid, was again heated to generate white smoke. Evaporated to about 10 mL remaining solution was cooled, 70 mL of water, the use of filter paper,
Filter paper and rinse with hot water and precipitation. Keep this filtrate as the filtrate A, for the determination of calcium oxide.
The filter paper and transferred to precipitate a platinum crucible, after a small fire ash, high-temperature oven at 900 ℃ ± 25 ℃ to constant mass burning, calling it
quality. After the residue was wetted with water, 8 drops of sulfuric acid was added followed by 15 mL of hydrofluoric acid, heated on a hot plate to produce white smoke. Steam until nearly dry,
After cooling, 5 mL of water, 3 drops of sulfuric acid and 10 mL of hydrofluoric acid, hot plate evaporation to near dryness on a hot plate heated to white smoke
Catch net. The crucible and then calcined at 900 ℃ ± 25 ℃ in to a constant quality. The mass loss after hydrofluoric acid is added in a sample of silica substance
the amount. Keep this residue B for the determination of aluminum oxide.
A.4.5 Calculation Results
Silica content of silicon dioxide (SiO2) mass fraction w1 and its value is expressed in%, according to formula (A.1) Calculated.
0211 × - = m
mmw (A.1)
Where.
1m - for the first time after a constant burning quality to value the quality of the crucible and precipitate in grams (g);
2m - the second (after adding the hydrofluoric acid treatment) value to the quality of constant quality after burning crucible and precipitate in grams (g);
m - mass of the sample value in units of grams (g).
Take the arithmetic mean of the parallel determination results of the measurement results, the results of two parallel determination of the absolute difference is not more than 0.1%.
A.5 Determination of aluminum oxide
A.5.1 Reagents and materials
A.5.1.1 potassium pyrosulfate.
A.5.1.2 ammonia.
A.5.1.3 hydrochloric acid. 11.
A.5.1.4 ammonium chloride solution. 20 g/L.
A.5.1.5 bromine thymol blue indicator solution. 1 g/L.
A.5.2 Analysis step
The residue B (A.4.4) after the determination of silicon dioxide and 2 g of potassium pyrophosphate to constant mass burning placed a platinum crucible at a high temperature furnace
Gradually warming to 650 ℃ ± 25 ℃ melt 5 min ~ 10 min. Cooling, hydrochloric acid solution, 20 mL, micro heat leaching and dissolved frit, finished
Full transferred to a 500 mL beaker, into a beaker with hot water wash lotion and a platinum crucible. Diluted with water to 350 mL ~ 400 mL, was added
5 drops of bromine thymol blue indicator solution, heated to a boil, remove, cooling, dropping ammonia until the blue appears, boil 5 min, the removal of ammonia.
Quantitative filter paper, and 6 parts of hot ammonium chloride solution and rinse the filter precipitate, the filter paper and precipitate transferred to a platinum crucible at 900 ℃ ± 25 ℃
Burning to a constant quality.
A.5.3 Calculation Results
Aluminum oxide content of aluminum oxide (Al2O3) mass fraction w2 and its value is expressed in%, according to formula (A.2) Calculated.
0212 × - = m
mmw (A.2)
Where.
1m - value quality at 900 ℃ ± 25 ℃ to constant mass burning platinum crucible and precipitate in grams (g);
2m - Numerical platinum crucible mass in grams (g);
m - sample mass (A.4.4) value in units of grams (g).
Take the arithmetic mean of the parallel determination results of the measurement results, the results of two parallel determination of the absolute difference is not more than 0.1%.
A.6 Determination of calcium oxide
A.6.1 Reagents and materials
A.6.1.1 sodium hydroxide solution. c (NaOH) = 1 mol/L.
A.6.1.2 disodium EDTA standard titration solution. c (EDTA) = 0.02 mol/L.
A.6.1.3 hydroxy naphthol blue indicator.
A.6.2 Analysis step
The prepared filtrate A (A.4.4), placed in 250 mL volumetric flask, dilute to the mark, shake. Pipette 50.00 mL solution described above
Was placed in a 250 mL Erlenmeyer flask, add 15 mL of sodium hydroxide solution and 300 mg hydroxy naphthol blue indicator under stirring, ethylenediamine
Disodium standard titration solution titrated to a solution blue as the end point. While the same treatment the blank test solution.
In addition to the blank test without the sample, the addition of reagents and other operations of the kind and amount (other than the standard titration solution) with the same Test.
A.6.3 Calculation Results
Calcium oxide content of calcium oxide (CaO) mass fraction w3 and its value is expressed in%, according to equation (A.3) Calculated.
] 1000 /) [(0
3 ××
- =
cMVV
(A.3)
Where.
V - Value titration solution consumed disodium EDTA standard titration solution volume in milliliters (mL);
V0 - Numerical blank test consumed disodium EDTA standard titration solution volume in milliliters (mL);
c - accurate disodium edetate standard titration solution concentration value in units of moles per liter (mol/L);
M - Numerical calcium oxide (CaO) molar mass of the units of grams per mole (g/mol) (M = 56.08);
m - mass of the sample (A.4.4) value in units of grams (g).
Take two parallel determination results of the arithmetic average of the measurement results, the results of parallel determination of the absolute difference is not more than 0.1%.
A.7 Determination of sodium oxide
A.7.1 Reagents and materials
A.7.1.1 perchloric acid.
A.7.1.2 hydrofluoric acid.
A.7.1.3 hydrochloric acid.
A.7.1.4 Sodium standard solution. 1 mL solution of sodium (Na) 0.1 mg.
Pipette 10.00 mL sodium standard solution according to HG/T 3696.2 prepared, placed in 100 mL volumetric flask, dilute to the mark, shake.
The solution was prepared prior to use.
A.7.1.5 sulfate standard solution. 1 mL solution containing sodium sulfate (Na2SO4) 100 mg.
Weigh 10.00 g after 95 ℃ ~ 105 ℃ drying 2 h, cooled to room temperature and anhydrous sodium sulfate, dissolved in water and transferred to 100 mL volumetric flask
Diluted with water to the mark, shake, placed in the refrigerator to save, backup.
A.7.1.6 two water. in line with GB/T 6682-2008 specified.
A.7.2 Instruments and Equipment
A.7.2.1 flame photometer.
A.7.2.2 conductivity meter.
A.7.3 Analysis step
A.7.3.1 Determination of sodium correction
A.7.3.1.1 Preparation of sample solution
Weigh 12.5 g sample was 105 ℃ ± 2 ℃ bake 2 h, the nearest 0.0002 g, placed in 400 mL water beaker 240 mL, high speed stirring
Mix at least 5 min. The mixture was completely transferred to 100 mL volumetric flask, dilute to the mark.
A.7.3.1.2 Preparation of standard solution
Pipette standard solution of sodium 0.00 mL, 0.50 mL, 1.00 mL, 2.00 mL, 5.00 mL, were placed in 100 mL volumetric flask,
Diluted with water to the mark.
A.7.3.1.3 Determination
Electrical conductivity meter testing and standard solutions. In the electrical conductivity of the vertical axis, the quality of sodium (mg) as abscissa, work
curve.
Results A.7.3.1.4 Correction sodium content calculation
Correction sodium content of sodium oxide (Na2O) mass fraction w 'and its value is expressed in%, according to formula (A.4) Calculated.
010,437.0 '
1 ×× =
mw (A.4)
Where.
Numerical quality test solution m1-- isolated from the working curve of sodium in milligrams (mg);
Numerical m-- sample mass, expressed in grams (g);
0.437-- sodium sulfate sodium oxide conversion factor.
Take the arithmetic mean of the parallel determination results of the measurement results, the results of two parallel determination of the absolute difference is not more than 0.05%.
A.7.3.2 Preparation of sample solution.
Weigh was 105 ℃ ± 2 ℃ bake a sample of about 0.5 g 2 h, to the nearest 0.0002 g, into a platinum crucible, with 8 to 10 drops of water dripping Run
wet. Perchloric acid was added 15 mL and 10 mL of hydrofluoric acid, in a hood on a hotplate until generate a large amount of perchloric acid white smoke, steam to near
Dry After cooling 10 mL of hydrofluoric acid and heated to generate dense white smoke again evaporated to near dryness, added 4 mL of hydrochloric acid was dissolved by heating,
Wash with hot water in a platinum crucible and lotion incorporated into the flask, fully transferred to a 500 mL volumetric flask was cooled, diluted with water to the mark, shake
uniform. Pipette 10.00 mL of the solution into 100 mL volumetric flask, dilute to the mark, shake. While the same treatment blank test solution
liquid.
A.7.3.3 Preparation of the blank test solution
In addition to the blank test solution without the sample, the type and amount of addition of reagents and other operating and measured in the same test.
A.7.3.4 Preparation of standard solutions
Pipette sodium standard solution 0.00 mL, 1.00 mL, 2.00 mL, 3.00 mL, 4.00 mL, were placed in 100 mL volumetric flask with water
Dilute to the mark.
A.7.3.5 Determination
The test solution, blank test solution and standard solution at a wavelength of 589 nm at zero adjustment water was measured line intensities. Sodium mass
The amount (mg) as abscissa corresponding spectral intensity as the ordinate, drawing working curve.
A.7.4 Calculation Results
Sodium oxide content of sodium oxide (Na2O) mass fraction w4 and its value is expressed in%, according to formula (A.5) calculated as follows. ()
'0
10348.1 301
4 wm
mmw - ××
× - = (A.5)
Where.
Numerical quality test solution m1-- isolated from the working curve of sodium in milligrams (mg);
Numerical quality blank solution m0-- isolated from the working curve of sodium in milligrams (mg);
Numerical m-- sample mass, expressed in grams (g);
1.348-- sodium sodium oxide conversion factor;
w '- as determined by A.7.3.1 correction sodium content, expressed as% values.
Take the arithmetic mean of the parallel determination results of the measurement results, the results of two parallel determination of the absolute difference is not more than 0.1%.
A.8 Determination of loss on ignition
A.8.1 Instruments and Equipment
A.8.1.1 temperature furnace. to control the temperature 1000 ℃ ± 50 ℃.
A.8.1.2 porcelain crucible.
A.8.2 Analysis step
Use to bake constant quality porcelain crucible at 1000 ℃ ± 50 ℃, weigh about 5 g samples, accurate to 0.0002 g. At 1000 ℃ ± 50 ℃
High-temperature furnace burning to constant mass, after cooling call quality.
A.8.3 Calculation Results
LOI mass fraction w5 and its value is expressed in%, according to formula (A.9) Calculated.
()
0135 × - = m
mmm
w (A.9)
Where.
1m - Numerical porcelain crucible mass in grams (g);
3m --1000 ℃ ± 50 ℃ high temperature furnace burning to constant quality after quality porcelain crucible and the sample value in units of grams (g);
m - mass of the sample value in units of grams (g).
Take the arithmetic mean of the parallel determination results of the measurement results, the results of two parallel determination of the absolute difference is not more than 0.2%.
A.9 Determination of fluoride
A.9.1 Reagents and materials
With GB/T 5009.18-2003 of Chapter 11.
A.9.1.1 hydrochloric acid solution. 111.
A.9.1.2 sodium acetate solution (3 mol/L).
Weigh 204g of sodium acetate (CH3COONa · 3H2O), was dissolved in 300 mL of water, adding acetic acid (1 mol/L) adjusted to pH 7.0, plus
Diluted with water to 500 mL.
A.9.1.3 sodium citrate solution (0.75 mol/L).
Weigh 110 g of sodium citrate (Na3C6H5O7 · 2H2O), was dissolved in 300 mL of water, add 14 mL of perchloric acid, and then diluted with water to 500
mL.
A.9.1.4 total ionic strength buffers.
Sodium acetate solution (A.9.1.2) and volume mixing sodium citrate solution (A.9.1.3), etc., use namely distribution.
A.9.1.5 fluoride standard solution. 1mL solution of fluorine (F) 0.01 mg;
Pipette 1.00 mL of fluoride standard solution according to HG/T 3696.2 prepared, placed in 100 mL volumetric flask, dilute to the mark,
Shake well. The solution was prepared prior to use.
A.9.2 Instruments and Equipment
With GB/T 5009.18-2003 of Chapter 12.
A.9.3 Analysis step
A.9.3.1 Weigh about 2 g samples, accurate to 0.0002 g, placed in stoppered Erlenmeyer flask, add 20 mL of hydrochloric acid solution to dissolve, sealed soak extraction
1 h (gentle shaking from time to time), should be avoided on the sample stick the bottle wall. The solution was filtered to a 50 mL volumetric flask, twice washed with hot water
Erlenmeyer flasks (as far as possible to stay in a conical flask insolubles) per 10 mL of water, and finally with 10 mL of hot water to clean the filter and the filtrate was incorporated into 50 mL
Volumetric flask. After cooling, diluted with water to the mark.
Pipette pipette 25.00 mL of the solution, placed in 50 mL volumetric flask, add 20 mL of total ionic strength buffer, add water to the mark,
Shake well and set aside.
A.9.3.2 Pipette 1.00 mL, respectively, 2.00 mL, 5.00 mL, 10.00 mL of fluoride standard solution, placed in 50 mL volumetric flask, add 10
mL solution of hydrochloric acid and 20 mL of total ionic strength buffer, add water to the mark, shake well and set aside.
A.9.3.3 fluorine electrode and the negative terminal calomel electrode and measuring instruments, the positive terminal of the coupling. Electrode into a plastic beaker filled with water, and put the cup
With a magnetic stir bar, open electromagnetic stirring and measuring instruments, reading balance the potential value of 2 to 3 times to replace the water until the electrode potential reaches Description
After the claims provisions of a sample solution can be carried out and the potential of the standard solution was measured.
A.9.3.4 ordinate the electrode potential, the quality of fluorine as the horizontal, using a semi-logarithmic paper drawing working curve, according to the sample potential
Isolated value corresponding mass of fluorine on the working curve.
A.9.4 Calculation Results
Fluoride content of fluorine (F) mass fraction w6 and its value is expressed in%, according to formula (A.6) Calculated.
6 ××× = -m
mw (A.6)
Where.
Numerical quality test solution m1-- isolated from the working curve of fluorine in milligrams (mg);
Numerical m-- sample mass, expressed in grams (g).
Take the arithmetic mean of the parallel determination results of the measurement results, the results of two parallel determination of the absolute difference is not more than 5%.
A.10 Determination of Lead
A.10.1 reagents and materials
A.10.1.1 4- methyl amyl ketone -2 (MIBK).
A.10.1.2 hydrochloric acid solution. 120.
A.10.1.3 ammonia solution. 11.
A.10.1.4 ammonium sulfate solution. 300 g/L.
Weigh 30g of ammonium sulfate [(NH4) 2SO4], dissolved in water and add water to 100 mL.
A.10.1.5 ammonium citrate solution. 250 g/L.
Weigh 25g of ammonium citrate, dissolved in water and add water to 100 mL.
A.10.1.6 diethyl dithiocarbamate (DDTC) solution. 50 g/L.
Weigh 5g diethyl dithiocarbamate, dissolved in water and add water to 100 mL.
A.10.1.7 lead standard solution. 1mL solution containing lead (Pb) 0.001 mg.
Pipette 1.00 mL of lead standard solution according to HG/T 3696.2 prepared, placed in 1000 mL volumetric flask, dilute to the mark, shake.
The solution was prepared prior to use.
A.10.1.8 bromothymol blue solution. 1 g/L.
A.10.1.9 two water. in line with GB/T 6682-2008 specified.
A.10.2 instruments and equipment
Atomic absorption spectrophotometer.
A.10.3 Analysis steps
A.10.3.1 prepared test solution
Weigh 10.00 g ± 0.01 g sample was placed in 250 mL beaker, add 50 mL of hydrochloric acid solution, cover the surface of the dish, slowly heated to
Boiling and kept boiling for 15 min, cooled, insolubles were allowed to stand for settling. The solution was filtered to a 100 mL volumetric flask three times with hot water clean
Wash the beaker (try to make insolubles remain in the beaker) per 10 mL of water, and finally with 15 mL of hot water to clean the filter and the filtrate was incorporated into 100 mL
Volumetric flask. After cooling, diluted with water to the mark, shake, backup, keep this solution as the filtrate C, for levels of lead, arsenic content, heavily
Determination of the genus.
Pipette 10.00 mL filtrate C, placed in 125 mL separatory funnel, add water to make 60 mL. Add 2 mL of ammonium citrate solution, 3 drops ~
5 drops of bromothymol blue indicator solution, the pH is adjusted with ammonia solution from yellow to blue, add 10 mL of ammonium sulfate solution, 10 mL diethyl ammonia
Yl sodium formate (DDTC) solution, shake. Place about 5 min, was added 10.00 mL 4- methyl amyl ketone -2 (MIBK), shake vigorously mention
Take 1 min, after standing layer, the aqueous layer was discarded, the 4-methyl amyl ketone -2 (MIBK) layer into a 10 mL stoppered graduated tube, and set aside. with
Similarly handle blank test solution.
In addition to the blank test without the sample, the type and amount of addition of reagents and other operating and measured in the same test.
A.10.3.2 prepared than standard reference solution
Pipette respectively, 0.00 mL, 2.00 mL, 4.00 mL, 6.00 mL, 8.00 mL lead standard solution is used, placed in five 125 mL Dispense
Funnel, each added 5 mL hydrochloric acid solution from the "additional water to 60 mL" start simultaneously with the test solution the same treatment.
A.10.3.3 Determination
The test solution and standard solution at a wavelength of 283.3 nm at water zero adjustment, the absorbance was measured. Quality of lead (mg) is a cross-sit
Standard, the corresponding absorbance as the ordinate, drawing working curve.
A.10.4 Calculation Results
Lead content of lead (Pb) mass fraction w7 and its value in mg/kg according to formula (A.7) calculated as follows.
7 ××
- = -m
mm
w (A.7)
Where.
m1 - Numerical test solution isolated from the working curve lead mass in milligrams (mg);
m0 - value blank test solution isolated from the working curve lead mass in milligrams (mg);
m - the value of the sample mass, in grams (g).
Take the arithmetic mean of the parallel determination results of the measurement results, the results of two parallel determination of the absolute difference is not more than 1 mg/kg.
A.11 Determination of Arsenic
A.11.1 reagents and materials
With GB/T 5009.76-2003 of Chapter 9.
A.11.2 instruments and equipment
With GB/T 5009.76-2003 Chapter 10.
A.11.3 Analysis steps
Pipette 10.00 mL filtrate C (A.10.3.1), placed in a conical flask arsenic measuring apparatus, the following according to GB/T 5009.76-2003 Chapter 11
operating.
Limits formulated solution. Pipette 3.00 mL of arsenic standard solution (1 mL solution containing 1.0μg As), and treated in the same sample at the same time.
A.12 Determination of Heavy Metals (as Pb) of
A.12.1 reagent
A.12.1.1 hydrochloric acid solution. c (HCl) ≈0.5 mol/L.
A.12.1.2 hydrochloric acid solution. 120.
A.12.1.3 ammonia solution. 13.
A.12.1.4 nitric acid solution. 19.
A.12.1.5 phenolphthalein indicator solution.
A.12.1.6 sodium sulfide glycerol solution.
A.12.1.7 acetate buffer solution. pH≈3.5.
Weigh 25.0 g ammonium acetate dissolved in 25 mL of water, add 45 mL of hydrochloric acid solution (A.12.1.1), with a hydrochloric acid solution (A.12.1.2) or ammonia
Aqueous solution adjusted to pH 3.5 of 5 (pH meter), diluted with water to 100 mL.
A.12.1.8 lead standard solution. 1 mL solution containing lead (Pb) 0.001 mg.
Pipette 1.00 mL of lead standard solution according to HG/T 3696.2 prepared, placed in 1000 mL volumetric flask, dilute to the mark, shake.
The solution was prepared prior to use.
A.12.2 Analysis steps
A.12.2.1 A tube. accurate Pipette 10.00 mL lead standard solution was placed in 50 mL colorimetric tube, add 5 mL of hydrochloric acid solution (A.12.1.2),
Water was added to 25 mL, was added 1 drop of phenolphthalein indicator solution was added dropwise a solution of hydrochloric acid (...
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