|
US$559.00 · In stock
Delivery: <= 3 days. True-PDF full-copy in English will be manually translated and delivered via email.
GB 25568-2010: The national food safety standards of food additives disodium hydrogen phosphate
Status: Obsolete
| Standard ID | Contents [version] | USD | STEP2 | [PDF] delivered in | Standard Title (Description) | Status | PDF |
| GB 25568-2010 | English | 559 |
Add to Cart
|
3 days [Need to translate]
|
The national food safety standards of food additives disodium hydrogen phosphate
| Obsolete |
GB 25568-2010
|
PDF similar to GB 25568-2010
Basic data | Standard ID | GB 25568-2010 (GB25568-2010) | | Description (Translated English) | The national food safety standards of food additives disodium hydrogen phosphate | | Sector / Industry | National Standard | | Classification of Chinese Standard | X40 | | Classification of International Standard | 67.220.20 | | Word Count Estimation | 14,183 | | 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 thermal phosphoric acid and caustic soda or sodium hydroxide as raw materials to produce food additives disodium hydrogen phosphate. | GB 25568-2010: The national food safety standards of food additives disodium hydrogen phosphate---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.
The national food safety standards of food additives disodium hydrogen phosphate
National Food Safety Standard
Food additives disodium hydrogen phosphate
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 disodium hydrogen phosphate
1 Scope
This standard applies to thermal phosphoric acid or caustic soda and sodium hydroxide as raw materials to produce food additives disodium hydrogen phosphate.
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 formula and relative molecular mass
Formula 3.1
Na2HPO4 · nH2O n = 0,2,12
3.2 relative molecular mass
141.96 (n = 0), 177.99 (n = 2), 358.14 (n = 12) (according to 2007 international relative atomic mass)
4. Technical Requirements
4.1 Sensory requirements. comply with Table 1.
Table 1 Sensory requirements
project
Claim
Testing method
Anhydrous Hydrate
Colorless to white color white proper amount of sample is placed in 50mL beaker, in natural light
Observe the color and texture. State organizations crystal powder
4.2 Physical indicators. to comply with Table 2.
Table 2. Physical and chemical indicators
Item Index Test Method
Disodium hydrogen phosphate (Na2HPO4) (dry basis), w /% ≥ 98.0 Appendix A A.4
Arsenic (As)/(mg/kg) ≤ 3 Appendix A A.5
Heavy metals (Pb)/(mg/kg) ≤ 10 Appendix A A.6
Lead (Pb)/(mg/kg) ≤ 4 Appendix A A.7
Fluorides (as F)/(mg/kg) ≤ 50 Appendix A A.8
Table 2. Physical and chemical indicators (cont.)
Item Index Test Method
Water-insoluble, w /% ≤ 0.2 A.9 in Appendix A
Loss on drying (Na2HPO4), w /%
(Na2HPO4 · 2H2O), w /%
(Na2HPO4 · 12H2O), w /%
5.0
18.0 to 22.0
61.0
Appendix A A.10
Appendix A
(Normative)
Testing method
A.1 Warning
Reagents The standard test methods used for toxic or corrosive shall be as careful operation immediately on contact with skin
Rinsed with water, severe cases should be treated immediately. When heating flammable and should not use an open flame.
A.2 General Provisions
The standard test methods and reagents used in water, at the time did not indicate other 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 prepared HG/T 3696.3 of.
A.3 Identification Test
A.3.1 Reagents and materials
A.3.1.1 nitric acid solution. 18.
A.3.1.2 ammonia solution. 11.
A.3.1.3 silver nitrate solution. 17g/L.
A.3.2 Analysis step
A.3.2.1 Identification of phosphate
Weigh about 1g sample was dissolved in 20 mL of water, adding a silver nitrate solution to form a yellow precipitate, this precipitate was dissolved in nitric acid solution or aqueous ammonia solution
liquid.
A.3.2.2 Identification of sodium ions
Weigh 1g sample, add water to dissolve 20mL. Platinum wire ring dipped in hydrochloric acid, in a colorless flame to burn. And then dipped in the test solution on the flame
Combustion, the flame should be bright yellow.
A.4 Determination of disodium hydrogen phosphate
A.4.1 gravimetric method (Arbitration Act)
A.4.1.1 Method summary
In an acidic medium to Quimociac as precipitating agent phosphate formed entirely quinoline phosphomolybdate precipitate, the precipitate was filtered, dried, weighed,
Calculation of disodium hydrogen phosphate content of the sample.
A.4.1.2 Reagents and materials
A.4.1.2.1 nitric acid solution. 11.
A.4.1.2.2 Quimociac solution.
A.4.1.3 instruments and equipment
A.4.1.3.1 sand core glass crucible. pore size 5μm ~ 15μm.
A.4.1.3.2 electric oven. the temperature can be controlled at 40 ℃ ± 2 ℃, 120 ℃ ± 2 ℃, 180 ℃ ± 2 ℃.
A.4.1.4 analysis step
A.4.1.4.1 Preparation of test solution
Weigh about 1.5g advance at 120 ℃ ± 2 ℃ drying 4h sample (Na2HPO4 · 12H2O first at 40 ℃ ± 2 ℃ drying 3h, then at 120 ℃
± 2 ℃ drying 4h), accurate to 0.000 2g, placed 100 mL beaker, dissolved in water and transferred to 1000 mL volumetric flask, diluted with water
To the mark, shake, dry filter (discarded first filtrate 20mL).
A.4.1.4.2 Determination
Pipette Pipette 20 .00mL test solution was placed in 250mL beaker, add 10 mL of nitric acid solution, add water to a total volume of about 100 mL.
Added 50 mL Quimociac solution, cover the surface of the dish and heated in a water bath until the material in the beaker reaches 75 ℃ ± 5 ℃ (intake in the hood
Line), incubated 30s (in addition of the reagents and the heating process can not use open flame can not be stirred, so as not to clot). Cooling, cooling
During stirring for 3 to 4 times previously at 180 ℃ ± 2 ℃ drying 45min under glass sand core crucible with suction. First supernatant was filtered,
Washing with decantation precipitate was washed 6 times, each time with water of about 30 mL, the precipitate was finally transferred to a sintered glass crucible, the precipitate was washed with water 4
Times. The glass sand core crucible together with precipitation into electric oven, the temperature was stabilized from the beginning of time, at 180 ℃ ± 2 ℃ drying 45min.
After removing the coolish, placed in the dryer to cool to room temperature and weighed.
Meanwhile blank test, but without addition of the sample, the other reagent type and the same amount was added to the test blank, and with
Test solutions were treated.
A.4.1.5 Calculation Results
Disodium hydrogen phosphate content of disodium hydrogen phosphate (Na2HPO4) mass fraction w1 and its value is expressed in%, according to formula (A.1) Calculated.
06404.0) (21
1 ××
× - =) (m
mm
w (A.1)
Where.
Numerical quality m1-- test solution was precipitated quinoline phosphomolybdate, in grams (g);
Numerical quality m2-- blank test solution was precipitated quinoline phosphomolybdate, in grams (g);
m-- sample mass value in grams (g);
0.06404-- Quinoline phosphomolybdate terms of coefficient of disodium hydrogen phosphate.
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.4.2 acid-base titration
A.4.2.1 Method summary
In the sample accurately an excess of hydrochloric acid standard titration solution, titration with standard sodium hydroxide solution to titrate excess hydrochloric acid standard titration solution
Fluid, indicating a pH meter jump point, according to the consumption of sodium hydroxide standard titration solution, disodium hydrogen phosphate content calculated.
A.4.2.2 Reagents and materials
A.4.2.2.1 hydrochloric acid standard titration solution. c (HCl) = 1mol/L.
A.4.2.2.2 sodium hydroxide standard titration solution. c (NaOH) = 1mol/L.
A.4.2.3 instruments and equipment
A.4.2.3.1 pH meter. Indexing is 0.02.
A.4.2.3.2 electromagnetic stirrer. stirring with a rotor.
A.4.2.3.3 electric oven. the temperature can be controlled at 40 ℃ ± 2 ℃, 120 ℃ ± 2 ℃.
A.4.2.4 analysis step
Weigh about 5g advance at 120 ℃ ± 2 ℃ drying 4h sample [(Na2HPO4 · 12H2O) first at 40 ℃ ± 2 ℃ drying 3h, then in
120 ℃ ± 2 ℃ drying 4h], accurate to 0.000 2g, placed 250 mL beaker, add 50 mL of water was added 40.00 mL buret accurate
Hydrochloric acid standard titration solution. Placed on a magnetic stirrer and stirred until the sample is completely dissolved. The pH meter electrode in the test solution with hydrogen
Sodium hydroxide standard titration solution titrate excess hydrochloric acid standard titration solution. Until pH≈4.0, the recording titration readings (V), the samples to eliminate
The volume of consumption hydrochloric acid standard titration solution (V1). Standard titration with sodium hydroxide solution and continue titration until pH≈8.8, the recording titration readings,
Calculate the volume consumed by the titration of sodium hydroxide standard titration solution to pH≈8.8 pH≈4.0 between two points (V2).
A.4.2.5 Calculation Results
Sample consumption hydrochloric acid standard titrant volume V1, according to the formula (A.2) Calculated.
twenty one
Vcc
- = (A.2)
Where.
Numerical V-- test solution was titrated to pH≈4.0 consumed sodium hydroxide standard titration solution volume in milliliters (mL);
The exact concentration of hydrochloric acid standard titration solution c1-- value in units of moles per liter (mol/L);
C2-- actual concentration of sodium hydroxide standard titration solution, expressed in moles per liter (mol/L).
When V1c1 or less V2c2, the content of disodium hydrogen phosphate, disodium hydrogen phosphate (Na2HPO4) mass fraction w1 and its value
In%, according to formula (A.3) Calculated.
1 ××× =
McVw (A.3)
When V1c1 more than V2c2, the content of disodium hydrogen phosphate, disodium hydrogen phosphate (Na2HPO4) mass fraction w1 and its value to the table%
Shows, according to the formula (A.4) Calculated.
10) 2 (31 122
1 ××× - =
McVcV
w (A.4)
Where.
Numerical hydrochloric acid standard titration V1-- test solution titration solution consumed to pH≈4.00 volume in milliliters (mL);
V2 - sodium hydroxide standard titration value between pH≈4.0 to pH≈8.8 titration solution consumed volume in milliliters (mL);
The exact concentration of hydrochloric acid standard titration solution c1-- value in units of moles per liter (mol/L);
C2-- numerical concentration of sodium hydroxide standard titration standard solution, unit mole per liter (mol/L);
m-- sample mass value in grams (g);
M-- numerical molar mass of disodium hydrogen phosphate (Na2HPO4), in units of grams per mole (g/moL) (M = 142.0).
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 0.3%.
A.5 Determination of Arsenic
A.5.1 diethyl dithiocarbamate silver colorimetry (Arbitration Act)
A.5.1.1 Reagents and materials
With GB/T 5009.76-2003 of Chapter 3.
A.5.1.2 analysis step
Weigh about 1g sample to the nearest 0.01g. Arsenic occurs put the bottle, add water to about 40mL, add 10 mL of sulfuric acid solution (11) to
Press down 6.3 GB/T 5009.76-2003 first law "lessons 0 mL, 2.00 mL, 4.00 mL, 6.00 mL, 8.00,10.00mL
Arsenic standard series should be the same treatment to the standard curve calibration "operation.
A.5.1.3 Calculation Results
Arsenic content quality of arsenic (As) scores w2 and its value in mg/kg according to formula (A.5) Calculated.
1000) (01
2 m
mm
- = (A.5)
Where.
Numerical quality test solution m1-- isolated from the working curve arsenic in micrograms (μg);
Numerical quality blank test solution m0-- isolated from the working curve arsenic in micrograms (μg);
m-- sample mass value 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 1mg/kg.
A.5.2 Gutzeit method
A.5.2.1 Reagents and materials
Reagents with GB/T 5009.76-2003 Chapter 9.
A.5.2.2 instruments and equipment
With GB/T 5009.76-2003 Chapter 10.
A.5.2.3 analysis step
Weigh 0.50g ± 0.01g sample was placed in measuring arsenic flask, add 20mL water. The following operation is the same GB/T 5009.76-2003 Chapter 11
"Plus 5mL hydrochloric acid, add water to 30mL not be deeper than the limits of arsenic Gutzeit."
Limits formulated solution. Pipette 1.50mL arsenic standard solution (1mL solution arsenic 1μg), the following actions with GB/T 5009.76-2003
Chapter 11, "plus 5mL hydrochloric acid, add water to 30mL taken Gutzeit compare." Simultaneously with the sample.
A.6 Determination of Heavy Metals
A.6.1 Reagents and materials
A.6.1.1 hydrochloric acid solution. 11.
A.6.1.2 ammonia solution. 23.
A.6.1.3 acetate buffer solution. pH≈3.5;
Weighed 25.0 g ammonium acetate, add 25 mL of water dissolved, and 45 mL hydrochloric acid solution, aqueous ammonia solution or hydrochloric acid solution and then adjusted to pH
3.5, dilute with water to 100 mL.
A.6.1.4 saturated hydrogen sulphide water.
A.6.1.5 Lead standard solution. 1mL solution containing lead (Pb) 0.01mg;
Pipette Pipette 1.00mL lead standard solution according to HG/T 3696.2 prepared, placed in 100mL volumetric flask, dilute to the mark,
Shake well. The solution was formulated before use.
A.6.1.6 phenolphthalein indicator solution. 10g/L.
A.6.2 Instruments and Equipment
Colorimetric tube. 50mL.
A.6.3 Analysis step
10.00g ± 0.01g sample is weighed, placed in 150mL beaker, add 80mL water, dissolved by heating, cooled after the transfer of 100 mL capacity
Volumetric flask, dilute to the mark, shake. Dry filter paper with medium speed two discarded initially 20mL solution, with a pipette take 20 mL
The test solution was placed in 50mL colorimetric tube, add 1 drop of phenolphthalein indicator solution, a solution of hydrochloric acid to the solution just as a colorless, add 5 mL of acetate buffer
Red solution, 10 mL of saturated hydrogen sulphide water, dilute to the mark, shake, in the dark place 5 min. Observation on white background, was the
Color can not be deeper than the standard colorimetric solution.
Preparation of standard color solution ratio. Pipette 2.00mL lead standard solution in 50mL colorimetric tube, add water to 20mL, add 5 mL of acetate
Dilution buffer solution, 10mL saturated hydrogen sulphide water, water to the mark, shake, in the dark place 5min. Simultaneously with the sample.
A.7 Determination of Lead
A.7.1 graphite furnace atomic absorption spectrophotometry (Arbitration Act)
A.7.1.1 Reagents and materials
A.7.1.1.1 nitric acid solution. 0.5mol/L;
Take 32mL of nitric acid was added to water, diluted to 1000mL.
A.7.1.1.2 ammonium dihydrogen phosphate solution. 20g/L;
Weigh 2.0g of ammonium dihydrogen phosphate, dissolved in water and diluted to 100mL.
A.7.1.1.3 Lead standard solution. 1mL solution containing lead (Pb) 0.1μg;
Pipette Pipette 1.00mL lead standard solution according to HG/T 3696.2 prepared, placed in 100mL volumetric flask, dilute nitric acid solution
To the mark. After Pipette 5.00mL solution was diluted to 500mL volumetric flask, dilute nitric acid solution to the mark. The solution was active
Formulated.
A.7.1.1.4 two water. in line with GB/T 6682-2008 the provisions.
A.7.1.2 instruments and equipment
Are nitric acid solution (15) soaked overnight with water repeatedly washed with deionized water rinse. A.7.1.2.1 The glassware used.
A.7.1.2.2 atomic absorption spectrophotometer (with furnace and lead hollow cathode lamp).
A.7.1.3 analysis step
A.7.1.3.1 Preparation of test solution
Weigh about 0.2g sample accurate to 0.01g, a 50mL beaker was added nitric acid to dissolve the sample, transferred to a 25mL capacity
Bottle with a nitric acid solution was diluted to the mark.
Blank test solution prepared simultaneously. In addition to the blank test solution without the sample, the kind and amount of other reagents with the test solution was added to complete
The same test solution with the same treatment.
A.7.1.3.2 curve plotted
Pipette lead standard solution 0mL, 5mL, 10mL, 20mL, 30mL, 40mL to six 50mL volumetric flask, with nitric acid
The solution was diluted to the mark, shake, this series of concentration was 0 ng/mL, 10ng/mL, 20ng/mL, 40ng/mL, 60ng/mL,
80ng/mL. Each draw 10μL, injection graphite furnace, measured obtaining the absorbance, the concentration of lead as abscissa and ordinate corresponding absorbance painted
System curve.
A.7.1.3.3 Determination
At a wavelength of 283.3nm at the instrument adjusted to the best working condition, respectively draw test solution and the blank test solution 10μL, inject graphite
Furnace, obtaining absorbance measurements, check the content to give the corresponding lead from the working curve.
A.7.1.3.4 using matrix modifiers
If the interference, then inject the right amount of matrix modifier ammonium dihydrogen phosphate solution, typically 5μL or the same amount of the sample to eliminate interference. draw
When the measurement sample was also added to the lead standard curve when the same amount of matrix modifier ammonium dihydrogen phosphate solution.
A.7.1.4 Calculation Results
Lead content of lead (Pb) mass fraction w3 and its value in mg/kg according to formula (A.6) Calculated.
2510) (
ccw × - = (A.6)
Where.
Numerical test solution c1-- isolated from the working curve of lead content, expressed in nanograms per milliliter (ng/mL);
c0 - Numerical blank test solution is isolated from the working curve of lead content, expressed in nanograms per milliliter (ng/mL);
25-- test correctly predicted capacity volume in milliliters (mL);
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 1 mg/kg.
A.7.2 Pyrrolidine dithiocarbamate (The APDC) Extraction
A.7.2.1 Reagents and materials
A.7.2.1.1 sulfuric acid.
A.7.2.1.2 hydrochloric acid.
A.7.2.1.3 nitrate.
A.7.2.1.4 chloroform.
A.7.2.1.5 sodium hydroxide solution. 250g/L;
Weigh 25g of sodium hydroxide dissolved in 100mL of water.
A.7.2.1.6 Pyrrolidine dithiocarbamate (The APDC) solution. 20g/L;
Weigh 2g Pyrrolidine dithiocarbamate (The APDC) was dissolved in 100mL water. Filtered before use.
A.7.2.1.7 Lead standard solution. 1mL solution containing lead (Pb) 0.005mg;
Pipette pipette 5mL lead standard solution according to HG/T 3696.2 prepared, placed in 1000mL volumetric flask, dilute to the mark,
Shake well. The solution was formulated before use.
A.7.2.1.8 precision pH test paper. 0.5 to 5.0.
A.7.2.1.9 two water. in line with GB/T 6682-2008 requirements.
A.7.2.2 instruments and equipment
Are nitric acid solution (15) soaked overnight with water repeatedly washed with deionized water rinse. A.7.2.2.1 The glassware used.
A.7.2.2.2 atomic absorption spectrophotometer (with lead hollow cathode lamp)
A.7.2.3 analysis step
A.7.2.3.1 Preparation of test solution
Weigh about 5g samples, accurate to 0.01g, placed in 150mL beaker, add 30mL water is added 1mL hydrochloric acid. Heated to boiling fraction
Diluted minutes, cooled with water to 100mL. With sodium hydroxide solution to adjust the pH of the solution is 1.0 to 1.5. The solution was transferred to a 250mL liquid separation
Funnel, diluted with water to about 200mL. Add 2mL Pyrrolidine dithiocarbamate (The APDC) solution, and mixed. Respectively 20mL
Extracted twice with chloroform, the extract was collected in 50mL beaker, steam bath and evaporated to dryness (this operation must be carried out in a fume hood), to residues
Nitrate residue was added 3mL, continue evaporated to near dryness. Nitric acid was added 0.5mL and 10mL water was heated until the solution volume of about 3 mL ~ 5mL.
Transferred to a 10mL volumetric flask, dilute to the mark, shake.
Preparation A.7.2.3.2 blank test solution
Taking into 30mL water 150mL beaker was added 1mL of hydrochloric acid. The following operation is the same in A.7.2.3.1 "boil a few minutes heating, cooling,
Diluted with water to 100mL transferred to a 10mL volumetric flask, diluted with water to the mark. "
A.7.2.3.3 Preparation of standard solution
Pipette 4.00mL lead standard solution was placed in 150mL beaker, add 1mL hydrochloric acid. The following operation is the same in A.7.2.3.1 "heated to boiling
Minutes, cooled, diluted with water to 100mL transferred to a 10mL volumetric flask, diluted with water to the mark. "
A.7.2.3.4 Determination
a) instrument conditions. resonance line 283.3nm; slit 0.7nm; air - acetylene flame.
b) Determination. The test solution, standard solution to import atomic absorption spectrophotometer, zero blank test solution, the test solution
Absorption value can not be higher than the standard solution absorbance.
A.8 Determination of fluoride
A.8.1 Reagents and materials
A.8.1.1 hydrochloric acid solution. 111.
A.8.1.2 sodium acetate solution. c (CH3COONa • 3H2O) about 3mol/L;
Weigh 204g of sodium acetate (CH3COONa • 3H2O), was dissolved in 300mL of water, add a solution of acetic acid (116) adjusting the pH to 7.0, add
Diluted with water to 500mL.
A.8.1.3 sodium citrate solution. c (Na3C6H5O7 • 2H2O) about 0.75mol/L;
Weigh 110g sodium citrate (Na3C6H5O7 • 2H2O) was dissolved in 300mL of water, diluted with 14mL of perchloric acid, add water to 500mL.
A.8.1.4 total ionic strength buffers;
Volume mixing sodium acetate and sodium citrate solution, etc., before use formulation.
A.8.1.5 fluoro standard solution. 1mL solution of fluorine (F) 0.010mg;
Pipette Pipette 10mL fluoro standard solution according to HG/T 3696.2 prepared, placed in 1000mL volumetric flask, dilute to the mark,
Shake well. The solution was formulated before use.
A.8.2 Instruments and Equipment
A.8.2.1 fluoride ion selective electrode.
A.8.2.2 saturated calomel electrode.
A.8.2.3 magnetic stirrer.
A.8.2.4 Potentiometer. Indexing is 0.02.
A.8.3 Analysis step
A.8.3.1 Instrument adjustment
The fluoride ion selective electrode (by manual activation) and a saturated calomel electrode and the negative terminal of the measuring instrument connected to the positive terminal of the electrode insertion Sheng
After the plastic cup of water, electromagnetic stirring (polyethylene rotor), read the value of the equilibrium potential, the replacement of 2 to 3 times the water until the potential value
After equilibration, the potential can be measured.
A.8.3.2 Determination
Weigh about 1g sample to the nearest 0.01g. A 50mL beaker, 10mL of water was added to dissolve the sample, transferred to a 50mL volumetric flask
Diluted, add 25mL total ionic strength buffer, 10mL hydrochloric acid solution, add water to the mark. Pour 25mL plastic beaker measuring
Given electrode potential.
A.8.3.3 draw the curve
Pipette respectively 1.00mL, 2.00mL, 4.00mL, 5.00mL, 6.00mL fluoro standard solution (corresponding to a fluorine content was 0.010mg,
0.020mg, 0.040mg, 0.050mg, 0.060mg) placed five 50mL volumetric flask, were added to each flask 25mL total from
Dilution strengths buffer, 10mL hydrochloric acid solution, add water to the mark. Poured into a plastic beaker 25mL measuring electrode potential.
Ordinate the electrode potential, the quality of fluorine (mg) as abscissa, the curve on semi-log graph paper, according to the sample electric
Bit value on the curve Richard fluorine quality.
A.8.4 Calculation Results
Fluoride content of fluorine (F) mass fraction w4 and its value in mg/kg according to formula (A.7) calculated as follows.
4 m
mw = (A.7)
Where.
m1-- potential value based on the measured value of the test solution from the working curve Richard fluorine mass, in milligrams (mg);
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 5 mg/kg.
A.9 Determination of insoluble matter
A.9.1 Instruments and Equipment
A.9.1.1 sand core glass crucible. pore size 5μm ~ 15μm.
A.9.1.2 electric oven. temperature can be controlled at 105 ℃ ± 2 ℃.
A.9.2 Analysis step
It weighs about 20g sample to the nearest 0.01g. Placed in 500mL beaker, add 250 mL of water, heated to boiling. It has been used in 105 ℃ hot
± 2 ℃ under dried to a constant mass of glass sand core crucible filtered, washed with 200mL water points and 10 washes. Then crucible together with glass frit
Dried to a constant mass insolubles ± 2 ℃ to 105 ℃.
A.9.3 Calculation Results
Water-insoluble mass fraction w5 and its value is expressed in%, according to formula (A.8) Calculated.
0215 × - = m
mmw (A.8)
Where.
Numerical m1-- glass sand core crucible and residue mass in grams (g);
Numerical m2-- glass sand core crucible mass in grams (g);
m-- sample mass value 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 0.03%.
A.10 Determination of loss on drying
A.10.1 instruments and equipment
Electric oven. the temperature can be controlled at 40 ℃ ± 2 ℃, 120 ℃ ± 2 ℃.
A.10.2 Analysis steps
Weigh approximately 10 g samples, accurate to 0.01g, placed in a pre ± 2 ℃ drying to constant mass at 120 ℃ weighing bottle. At 120 ℃ ± ...
Tips & Frequently Asked Questions:Question 1: How long will the true-PDF of GB 25568-2010_English be delivered?Answer: Upon your order, we will start to translate GB 25568-2010_English as soon as possible, and keep you informed of the progress. The lead time is typically 1 ~ 3 working days. The lengthier the document the longer the lead time. Question 2: Can I share the purchased PDF of GB 25568-2010_English with my colleagues?Answer: Yes. The purchased PDF of GB 25568-2010_English will be deemed to be sold to your employer/organization who actually pays for it, including your colleagues and your employer's intranet. Question 3: Does the price include tax/VAT?Answer: Yes. Our tax invoice, downloaded/delivered in 9 seconds, includes all tax/VAT and complies with 100+ countries' tax regulations (tax exempted in 100+ countries) -- See Avoidance of Double Taxation Agreements (DTAs): List of DTAs signed between Singapore and 100+ countriesQuestion 4: Do you accept my currency other than USD?Answer: Yes. If you need your currency to be printed on the invoice, please write an email to [email protected]. In 2 working-hours, we will create a special link for you to pay in any currencies. Otherwise, follow the normal steps: Add to Cart -- Checkout -- Select your currency to pay.
|