Some standard content:
HG2452—1993
Chemical Industry Standard of the People's Republic of China
Food Additive Potassium Carbonate
1 Subject Content and Scope of Application
HG 2452—1993
This standard specifies the technical requirements, test methods, inspection rules, as well as marking, packaging, transportation and storage of food additive potassium carbonate.
This standard applies to food additive potassium carbonate produced by electrolytic carbonization, ion exchange and other processes. This product is used as a leavening agent in food.
Molecular formula: K, CO3
Relative molecular mass: 138.21 (according to the international relative atomic mass in 1989) 2 Reference standards
Packaging, storage and transportation diagrams
Preparation of standard solutions for titration analysis (volume analysis) of chemical reagents GB602
Preparation of standard solutions for determination of impurities in chemical reagents Preparation of preparations and products used in chemical reagent test methods GB/T3049
GB/T3050
GB/T6678
GB6682
GB84 50
GB8451
GB8946
GB10454
3 Technical requirements
General method for determination of iron content in chemical products Phenanthroline spectrophotometric method General method for determination of chloride content in inorganic chemical products Potentiometric titration method General rules for sampling of chemical products
Rules and test methods for water used in analytical laboratories Determination of arsenic in food additives
Test method for heavy metal limits in food additives Plastic woven bags
Flexible concentrated bags
3.1 Appearance: white powder or granular crystals. 3.2 Food additives Potassium carbonate should meet the requirements of the following table: Item
Potassium carbonate (K, CO3) content (after ignition) Chloride (KCI) content
Sulfur compound (K2SO4) content
Iron (Fe) content
Water-insoluble matter content
Heavy metal (Pb) content
Arsenic (As) content
Ignition loss
Note: Ignition loss index is only applicable to product packaging inspection. Test method
The reagents and water used in this standard, unless otherwise specified, refer to analytical pure reagents and grade 3 water specified in GB6682.
Standard solutions, impurity standard solutions, preparations and products required in the test, unless otherwise specified, are prepared in accordance with the provisions of GB601, GB602 and GB603. Approved by the Ministry of Chemical Industry of the People’s Republic of China on July 5, 1993 and implemented on January 1, 1994
HG2452—1993
4.1 Identification
4.1.1 Reagents and materials
4.1.1.1 Hydrochloric acid (GB622);
4.1.1.2 Anhydrous ethanol (GB678):
4.1.1.3 Calcium oxide (GB1262) saturated solution; Preparation: Weigh 3g of calcium oxide and put it into 1000mL of water. After vigorous stirring or shaking, let it stand to clarify and take the clarified solution for later use.
4.1.1.4 Magnesium sulfate (GB671) solution: 120g/L; 4.1.1.5 Sodium tetraphenylborate (HG3-1164) ethanol solution: 34g/L; Preparation: Weigh 3.4g sodium tetraphenylborate, dissolve in 100mL anhydrous ethanol, filter and set aside if necessary. 4.1.1.6 Red litmus paper.
4.1.2 Identification method
4.1.2.1 Carbonate
a. Take 50mL of 1g/mL test solution, place it in a 250mL conical flask, add hydrochloric acid dropwise, and gas will be released. This gas is introduced into a saturated solution of calcium oxide, and white turbidity will occur. b. Take an appropriate amount of 1g/mL test solution, add magnesium sulfate solution dropwise, and white precipitation will occur. 4.1.2.2 Potassium salt
a. Take an appropriate amount of 1g/mL test solution and add sodium tetraphenylborate solution. A large amount of white precipitate will be generated. b. Take an appropriate amount of 1g/mL test solution and place it in a conical flask. Heat the conical flask on an electric stove. The wet red litmus paper placed at the mouth of the flask should not change color. 4.2 Determination of potassium carbonate content
4.2.1 Potassium tetraphenylborate gravimetric method (arbitration method) 4.2.1.1 Method summary
In a weakly acidic medium, potassium carbonate and sodium tetraphenylborate generate potassium tetraphenylborate precipitate. Calculate the potassium carbonate content by deducting the mass of potassium chloride and potassium sulfate from the mass of potassium tetraphenylborate precipitate. 4.2.1.2 Reagents and materials
4.2.1.2.1 Anhydrous ethanol (GB678);
4.2.1.2.2 Glacial acetic acid (GB676) solution: 1+9; 4.2.1.2.3 Sodium tetraphenylborate (KG3-1164) ethanol solution: 34g/L; Preparation: Weigh 3.4g sodium tetraphenylborate and dissolve it in 100mL anhydrous ethanol (4.2.1.2.1). Filter and set aside if necessary.
4.2.1.2.4 Potassium tetraphenylborate;
Preparation: Weigh 0.2g potassium carbonate (GB1397), accurate to 0.0001g. Dissolve it in 300mL water, add 5 drops of methyl red indicator solution, adjust to red with acetic acid solution, heat to 40℃ on a water bath, add 45mL sodium tetraphenylborate ethanol solution under stirring, leave it for 10min and remove it. Cool to room temperature, filter with a clean filter, wash with 5% ethanol solution, transfer the precipitate, and drain; remove the filter, wash along the filter wall with 10mL of anhydrous ethanol for 5 times, and drain. 4.2.1.2.5 Saturated ethanol solution of potassium tetraphenylborate; Prepare by adding 50mL of 95% ethanol (GB679) and 950mL of water to the prepared potassium tetraphenylborate, and shake it thoroughly to saturate it. Dry filter before use. 4.2.1.2.6 Methyl red (HG3-958) ethanol solution: 1g/L. 4.2.1.3 Instruments and equipment
4.2.1.3.1 Filter: filter plate pore size 5~15um. 4.2.1.4 Analysis steps
Weigh 0.8-0.85g of the sample burned to constant weight at 270-300℃; accurate to 0.0002g, dissolve in water, transfer to a 500mL volumetric flask, dilute to scale with water, and shake well. If the test solution is turbid, dry filter and discard the initial 10-15mL filtrate. Use a pipette to transfer 25mL of the test solution into a 100mL beaker, add 35mL of water, 1 drop of methyl red indicator, adjust to red with acetic acid solution, heat to 40℃ in a water bath, add 8.5mL of sodium tetraphenylborate ethanol solution dropwise while stirring, leave for 10min, remove, and cool to room temperature. Filter with a filter that has been dried at 120-125°C to constant weight, transfer the precipitate with a saturated solution of potassium tetraphenylborate in ethanol, and wash the precipitate 3 to 4 times with 15 mL of a saturated solution of potassium tetraphenylborate in ethanol each time and drain. Remove the filter, wash along the filter wall once with 2 mL of anhydrous ethanol, drain, and dry at 120-125°C to constant weight.
4.2.1.5 Expression of analysis results
The potassium carbonate (KzCO,) content (X) expressed as mass percentage is calculated according to formula (1): mjx0.1928
Wherein: mr
x100—(0.9269X+0.7931X,)
—(0.9269X4+0.7931X)..·.··.(1)Mass of potassium tetraphenylborate precipitate, g;
Mass of sample, g;
-Coefficient for converting potassium tetraphenylborate into potassium carbonate; Content of chloride (in KCl) determined in accordance with Article 4.5 of this standard, %; Content of sulfur compounds (in K,SO4) determined in accordance with Article 4.6 of this standard, %; Coefficient for converting potassium chloride into potassium carbonate; -Coefficient for converting potassium sulfate into potassium carbonate. 4.2.1.6 Allowable difference
The arithmetic mean of the parallel determination results shall be taken as the determination result. The absolute difference between the two parallel determination results shall not exceed 0.3%.
4.2.2 Acid-base titration method
4.2.2.1 Method summary
Potassium carbonate is alkaline in aqueous solution. Titrate the test solution with hydrochloric acid standard titration solution. Determine the content of carbonic acid by deducting the consumption of sodium carbonate, calcium carbonate and magnesium carbonate based on the consumption of hydrochloric acid standard titration solution.
4.2.2.2 Reagents and materials
4.2.2.2.1 Hydrochloric acid (GB622) standard titration solution: c (HCI) is about 0.5 mol/L; bromocresol green (HG3-1226)-methyl red (HG3-958) mixed indicator solution. 4. 2. 2. 2. 2
4.2.2.3Instruments and equipment
4.2.2.3.1 High temperature furnace: can be controlled to work at 270～300℃. 4.2.2.4 Analysis steps
Weigh about 1g of the sample burned to constant weight at 270～300℃, accurate to 0.0002g. Place in a 250mL conical flask and add 50mL of water to dissolve. Add 5 drops of bromocresol green-methyl red mixed indicator solution and titrate with hydrochloric acid standard titration solution until the solution changes from green to dark red. Boil the solution for 2 minutes, cool it, and continue to titrate until it turns dark red, and perform a blank test at the same time.
4.2.2.5 Expression of analysis results
Approved by the Ministry of Chemical Industry of the People's Republic of China on July 5, 1993 and implemented on January 1, 1994
HG2452—1993
The potassium carbonate (K2CO) content (X) expressed in mass percentage is calculated according to formula (2): (V-Vo)cx0.06910
6.910 (V-Vo) c
Wherein: V -
x100-3.006X25.686X3
—3.006X2—5.686X3
（2）
The volume of the standard hydrochloric acid solution consumed in the titration of the test solution, mL; -The volume of the standard hydrochloric acid solution consumed in the titration of the blank test solution, mL: The actual concentration of the standard hydrochloric acid solution, mol/L; Mass, g;
Mass of potassium carbonate expressed in grams equivalent to 1.00mL hydrochloric acid standard titration solution [c (HCI) = 1.000mol/L;
Sodium content measured in accordance with Article 4.3 of this standard, %X2
Calcium and magnesium (in terms of Mg) content measured in accordance with Article 4.4 of this standard, %-coefficient for converting sodium into potassium carbonate;
-coefficient for converting magnesium into potassium carbonate.
4.2.2.6 Allowable difference
The arithmetic mean of the parallel determination results is taken as the determination result, and the absolute difference between the two parallel determination results shall not exceed 0.3%.
4.3 Determination of sodium content
4.3.1 Summary of the method
Sodium emits characteristic light with a certain wavelength in a high-temperature flame, and its light intensity is proportional to the sodium ion concentration in the test solution. Determine the sodium content in the sample by measuring the intensity of the emitted light. 4.3.2 Reagents and materials
4.3.2.1 Potassium carbonate (spectrally pure) solution: 20g/L4.3.2.2 Sodium standard solution: 1mL solution contains 0.1mgNa. 4.3.3 Instruments and equipment
4.3.3.1 Flame photometer
4.3.4 Drawing of working curve
In a series of 250mL volumetric flasks, add 10mL of potassium carbonate solution to each. Then add 0.00, 2.50, 5.00, and 10.00mL of sodium standard solution respectively. Dilute with water to the scale and shake well. Use a flame photometer to zero with water at a wavelength of 589nm and measure the emission intensity. Draw a working curve with the sodium content as the horizontal axis and the corresponding emission intensity after deducting the reagent blank as the vertical axis. 4.3.5 Analysis steps
Weigh about 0.2g of the sample, accurate to 0.0002g, and place it in a beaker. Add a small amount of water to dissolve, transfer to a 250mL volumetric flask, dilute to the mark with water, and shake the spoon. Use a flame photometer at a wavelength of 589nm, adjust to zero with water, and measure the emission intensity of the test solution. 4.3.6 Expression of analysis results
The sodium (Na) content (X2) expressed as mass percentage shall be calculated according to formula (3):mix10-3
m(1-Xs)
Approved by the Ministry of Chemical Industry of the People's Republic of China on July 5, 1993 and implemented on January 1, 1994
HG2452-1993
10m(1-Xg)
.......(3)
The mass of sodium in the test solution obtained from the working curve, mg; Where: m
The mass of the test sample, g;
XgThe loss on ignition determined in accordance with Article 4.11 of this standard, %. 4.3.7 Allowable difference
The arithmetic mean of the parallel determination results shall be taken as the determination result. The absolute difference between the two parallel determination results shall not exceed 0.005%.
4.4 Determination of total calcium and magnesium
4.4.1 Summary of the method
When pH is ~ 10, Ca2+, Mg2+ and EDTA form complexes in ammonia-ammonium chloride buffer solution. Determine the total calcium and magnesium based on the consumption of EDTA standard titration solution. 4.4.2 Reagents and materials
4.4.2.1 Hydrochloric acid (GB622) solution: 1+1; 4.4.2.2 Ammonia water (GB631) solution: 2+34.4.2.3 Ammonia-ammonium chloride buffer solution A: pH ~ 104.4.2.4 Magnesium standard solution: 1mL solution contains 1mgMg; Preparation: Weigh 1.660g of magnesium oxide burned to constant weight at 800℃, dissolve in 25mL hydrochloric acid and a small amount of water, transfer to a 1000mL volumetric flask, dilute to scale with water, and shake well. 4.4.2.5 Disodium ethylenediaminetetraacetic acid (EDTA) (GB1401) standard titration solution: c(EDTA) is about 0.05 mol/L.
4.4.2.6 Eriochrome black T indicator
4.4.3 Instruments and equipment
4.4.3.1 Microburette: the graduation value is 0.02 mL. 4.4.4 Analysis steps
Weigh about 5 g of sample, accurate to 0.01 g; place in a 250 mL conical flask, add 90 mL of water to dissolve; add hydrochloric acid solution to neutralize to pH ~ 4 (check with pH test paper), heat and boil for 5 minutes, and cool. Use a pipette to transfer 5.00 mL of magnesium standard solution, adjust pH to 8 with ammonia water (check with pH test paper); add 5 mL of ammonia-ammonium chloride buffer solution A, add 0.1 g of chromium black T indicator, and shake well. Titrate with EDTA standard titration solution until the solution changes from purple to blue.
Carry out a blank test at the same time and under the same conditions as the sample, except that no sample is added. 4.4.5 Expression of analysis resultswwW.bzxz.Net
The total amount of calcium and magnesium (in terms of Mg) (X3) expressed as mass percentage is calculated according to formula (4): (V-Vo) cx0.02431
m(1-X)
2.431 (V-Vo) c
m (1-Xg)
Wherein: V
（4）
-volume of EDTA standard titration solution consumed in titrating the test solution, mL; volume of EDTA standard titration solution consumed in titrating the blank test solution, mL; -actual concentration of EDTA standard titration solution, mol/L; mass of test material, g;
X loss on ignition determined in accordance with Article 4.11 of this standard, %; approved by the Ministry of Chemical Industry of the People's Republic of China on July 5, 1993, and implemented on January 1, 1994
HG2452—1993
mass of magnesium in grams equivalent to 1.00mL EDTA standard titration solution [c(EDTA)=1.000mol/L0.02431
4.4.6 Allowable difference
Take the arithmetic mean of the parallel determination results as the determination result, and the absolute difference between the two parallel determination results shall not exceed 0.005%.
4.5 Determination of chloride content
4.5.1 Method summary
Same as Article 2 of GB3050.
4.5.2 Reagents and materials
4.5.2.1 Potassium chloride (GB10736) standard solution: c (KCI) = 0.005 mol/L; Preparation: Weigh 1.864g of standard potassium chloride burned to constant weight at 500-600℃, accurate to 0.001g. Place in a beaker, add water to dissolve, transfer all to a 500mL volumetric flask, dilute with water to the scale, and shake well. Use a pipette to transfer 10mL of the solution to a 100mL volumetric flask, dilute with water to the scale, and shake well. 452.2 Silver nitrate (GB670) standard titration solution: c (AgNO) is about 0.005 mol/L. Preparation: Use a pipette to transfer 5 mL of the silver nitrate standard titration solution prepared according to GB601, place it in a 100 mL volumetric flask, dilute it to the mark with water, and shake it well. Others are the same as Article 4 of GB3050.
4.5.3 Instruments and equipment
The same as Article 3 of GB3050.
4.5.4 Analysis steps
Weigh 1.9-2.1 g of the sample to an accuracy of 0.01 g, place it in a 50 mL beaker, and moisten it with a small amount of water. Add 4 mL of nitric acid solution to dissolve the sample, add 1 drop of bromophenol blue indicator, continue to add nitric acid solution until the test solution turns yellow, and then add 15 mL of ethanol. The following operations are as described in Article 4.7.3 of GB3050, from "..Put in an electromagnetic stirrer..." to ".Record the starting potential value". Then, titrate with silver nitrate standard solution, first add 0.5mL, then add 0.1mL gradually, and then proceed as described in Article 4.7.3 of GB3050 starting from "record the total volume after each addition of silver nitrate standard solution". 4.5.5 Blank test
In a 50mL beaker, add 4mL nitric acid solution, adjust the pH value to neutral with sodium hydroxide solution (check with pH test paper), and then start from "add 1 drop of bromophenol blue indicator...", and perform a blank test at the same time as the test solution.
4.5.6 Expression of analytical results
The chloride content (in KCI) expressed as mass percentage (X4) is calculated according to formula (5): (V4-Vs)cX0. 07455
mx(1-Xs)
7.455(V4—Vs)c
mx(1-Xg)
Wherein: V
·（5）
the volume of standard silver nitrate solution consumed in titrating the test solution, mL; the volume of standard silver nitrate solution consumed in titrating the blank test solution, mL; - the actual concentration of the standard silver nitrate solution, mol/L; the mass of the sample, g:
Xgthe loss on ignition determined in accordance with Article 4.11 of this standard, %; 0.07455-
the mass of potassium chloride in grams equivalent to 1.00mL of standard silver nitrate solution [c(AgNO3)=1.000mol/L| . Approved by the Ministry of Chemical Industry of the People's Republic of China on July 5, 1993 and implemented on January 1, 1994
HG2452-1993
4.5.7 Allowable difference
The arithmetic mean of the parallel determination results shall be taken as the determination result, and the absolute difference between the two parallel determination results shall not exceed 0.003%.
4.6 Determination of sulfur compound content
4.6.1 Summary of the method
Use hydrogen peroxide to convert all sulfur compounds in potassium carbonate into sulfates; in the hydrochloric acid medium, sulfate ions and barium ions form sulfuric acid precipitates. Compare the suspension with the standard turbidity solution to determine the sulfur compound content.
4.6.2 Reagents and materials
4.6.2.130 % hydrogen peroxide (GB6684); 4.6.2.2 95% ethanol (GB679);
4.6.2.3 Hydrochloric acid (GB622) solution: 1+11: 4.6.2.4 Chloride (GB652) solution: 100g/L 4.6.2.5 Potassium sulfate (HG3920): 1mL solution contains 0.10mgK2SO4. Preparation: Accurately weigh 0.1000g of anhydrous potassium sulfate (K, S04) dried to constant weight at 105-110℃. Dissolve in water, transfer to a 1000mL volumetric flask, dilute to scale with water, and shake well. 4.6.3 Analysis steps
Weigh about 10g of sample, accurate to 0.01g, dissolve in water, transfer to a 100mL volumetric flask, dilute to scale with water, and shake well. Use a pipette to transfer 10mL of the test solution into a 50mL beaker, add 2 drops of hydrogen peroxide, neutralize with 15mL of hydrochloric acid solution, and heat to boil for 2 minutes. After cooling, pour into a 50mL colorimetric tube, rinse the beaker with a small amount of water, pour into the colorimetric tube, add 2mL of hydrochloric acid solution, dilute to 40mL with water, then add 5mL of ethanol and 3mL of chlorinated sodium solution, shake well, keep in a 30-35℃ water bath for 10 minutes, dilute to the scale with water and shake well; compare with the standard turbidity solution. The standard turbidity solution is in 4 50mL colorimetric tubes, each with 0.00, 0.50, 1.00, and 1.50mL of potassium sulfate standard solution. Add 10mL of water and 2 drops of hydrogen peroxide to each, and perform the same operation as the sample from "add 2mL of hydrochloric acid solution...".
4.6.4 Expression of analysis results
The content of sulfur compounds (in terms of K2SO4) (Xs) expressed as mass percentage is calculated according to formula (6): VX0.0001
mx(1-Xg) ×
Wherein: V
: (6)
10m(1-Xs)
The volume of potassium sulfate standard solution contained in the standard turbidimetric solution corresponding to the turbidity of the test solution, mL;
The mass of the test sample, g;
XThe loss on ignition determined in accordance with Article 4.11 of this standard, %; The mass of potassium sulfate in 0.0001-
-1.00mL potassium sulfate standard solution, g. 4.7 Determination of iron content
4.7.1 Summary of the method
Same as Article 2 of GB3049.
4.7.2 Reagents and materials
4.7.2.1 Hydrochloric acid (GB622);
4.7.2.2 Ammonia (GB631) solution: 1+1; other contents are the same as those in Article 3 of GB3049.
Approved by the Ministry of Chemical Industry of the People's Republic of China on 1993-07-05 and implemented on 1994-01-01
HG2452-1993
4.7.3 Instruments and equipment
4.7.3.1 Spectrophotometer: with a 3cm absorption cell. 4.7.4 Drawing of working curve
Draw the working curve according to Article 5.3 of GB3049 using a 3cm absorption cell and the corresponding amount of iron standard solution.
4.7.5 Analysis steps
4.75.1 Preparation of test solution
Weigh about 2g of sample, accurate to 0.01g, and place in a 100mL beaker; add 30mL of water to dissolve, add 4mL of hydrochloric acid, heat and boil for 3min, and cool. 4.7.5.2 Preparation of blank test solution
In a 100mL beaker, add 30mL of water and 4mL of hydrochloric acid, adjust the pH value to neutral with ammonia solution (check with pH test paper), heat and boil for 3min, and cool. 4.7.5.3 Determination
For the test solution and blank test solution, proceed according to Article 5.4 of GB3049 starting from "If necessary, add water to 60mL."
4.7.6 Expression of analysis results
The iron (Fe) content (X) expressed as mass percentage is calculated according to formula (7): (mi-mo)×10-3
m(1-Xg)
10m(1-X)
Wherein: mr
-the mass of iron in the test solution found from the working curve, mg; -the mass of iron in the blank test solution found from the working curve, mg; the mass of the test sample, g;
the loss on ignition determined in accordance with Article 4.11 of this standard, %. 4.7.7 Allowable difference
The arithmetic mean of the parallel determination results is taken as the determination result. The absolute difference between the two parallel determination results shall not exceed 0.0005%.
4.8 Determination of water-insoluble matter content
4.8.1 Summary of the method
Dissolve the sample in water, filter it with a Gooch crucible, and then dry the insoluble matter to constant weight. Determine the water-insoluble matter content based on the mass of the insoluble matter.
4.8.2 Reagents and materials
4.8.2.1 Hydrochloric acid (GB622) solution: 1+34.8.2.2 Potassium carbonate (GB1397) solution: 70g/L4.8.2.3 Phenolyl (GB10729) ethanol solution: 10g/L; 4.8.2.4 Acid-washed asbestos (HG3-1062): Take an appropriate amount of acid-washed asbestos and soak it in hydrochloric acid solution, boil it for 20 minutes, filter it with a Buchner funnel and wash it with water until it is neutral. Then soak it in potassium carbonate solution and boil it for 20 minutes, filter it with a Buchner funnel and wash it with water until it is neutral, mix it with water to make it into a paste, and set it aside. 4.8.3 Instruments and equipment
4.8.3.1 Gooch crucible: 20mL.
4.8.4 Analysis steps
4.8.4.1 Preparation for filtration
Approved by the Ministry of Chemical Industry of the People's Republic of China on July 5, 1993 and implemented on January 1, 1994
HG2452-1993
Place the Gooch crucible on the suction flask, evenly spread a layer of asbestos on the upper and lower sides of the sieve plate, each layer is about 3mm thick, and wash it with steamed filling water until the filtrate does not contain cotton wool. Move the Gooch crucible into an electric oven, dry it at 105-110℃, and then weigh it. Repeat the operation from "washing with distilled water until the filtrate does not contain cotton wool" until the Gooch crucible has a constant weight.
Place the Gooch crucible on the filtration bottle, wet the asbestos layer with water and set aside. 4.8.4.2 Determination of the sample
Weigh about 20g of the sample, accurate to 0.01g. Place it in a 400mL beaker, add 300mL of water to dissolve it. Filter it with the prepared Gooch crucible. Wash the insoluble matter with distilled water until 20mL of the washing solution plus 2 drops of phenol anhydride does not show red. Dry the insoluble matter and the Gooch crucible at 105110℃ to constant weight. 4.8.5 Expression of analysis results
The water-insoluble content (X) expressed as a mass percentage is calculated according to formula (8): (mi-mo)
m(1-Xs)
100(ml-mo)
(8)
m(1-X)
-the mass of Goossens, g;
where: mo
-the mass of Goossens and insoluble matter, g;
the mass of the sample, g;
the loss on ignition determined in accordance with Article 4.11 of this standard, %. 4.8.6 Allowable difference
The arithmetic mean of the parallel determination results is taken as the determination result. The absolute difference between the two parallel determination results shall not exceed 0.005%.
4.9 Determination of heavy metal content
4.9.1 Summary of the method
Same as Article 2 of GB8451.
4.9.2 Reagents and materials
4.9.2.1 Hydrochloric acid (GB622) solution: 1+1; 4.9.2.2 Hydrochloric acid (GB622) solution: 1+94.9.2.3 Saturated sodium sulfide solution;
Preparation: Weigh 5g sodium sulfide and dissolve it in a mixture of 10mL water and 30mL propylene glycol. 4.9.2.4 Lead standard solution: 1mL solution contains 0.01mgPb. Preparation: Use a pipette to transfer 10mL of the lead standard solution prepared according to GB602, place it in a 100mL volumetric flask, dilute to the mark with water, and shake well. This solution is prepared when used. Others are the same as Article 3 of GB8451.
4.9.3 Analysis steps
Tube A: In a 50mL colorimetric tube, transfer 2.00mL of the lead standard solution and add water to 25mL. Tube B and Tube C: Weigh 1.00+0.01g of sample each, place in a 50mL colorimetric tube, and add 21mL of water to dissolve. Add about 4mL of hydrochloric acid solution (4.9.2.1) dropwise, and when the solution stops bubbling, pipette 2.00mL of lead standard solution into tube C.
The following operations are carried out according to Article 6 of GB8451 starting from "mix and add 1 drop of 1% phenol anhydride indicator."
4.10 Determination of arsenic content
4.10.1 Summary of the method
Approved by the Ministry of Chemical Industry of the People's Republic of China on 199307-05 and implemented on 1994-01-01
HG2452-1993
Same as Article 2.1 of GB8450.
4.10.2 Reagents and materials
4.10.2.1 Arsenic standard solution: 1 mL of solution contains 0.001 mg As. Preparation: Use a pipette to transfer 10 mL of the arsenic standard solution prepared according to GB602, place it in a 1000 mL volumetric flask, dilute it to the mark with water, shake it well, and prepare this solution for use. Others are the same as GB8450 Sections 1.2.3, 1.2.7~1.2.10 and 2.2.3. 4.10.3 Instruments and equipment
Same as GB8450 Section 2.3.
4.10.4 Analysis steps
Weigh 1.00±0.01 g of sample, place it in the conical flask of the arsenic measuring device, and add 25 mL of water to dissolve the sample. Add hydrochloric acid dropwise to neutralize until the solution does not produce bubbles (about 1.5 mL of hydrochloric acid), then add 5 mL of hydrochloric acid, and the following operations shall be carried out according to Article 2.4 of GB8450 starting with "add 5 mL of potassium iodide solution". The color of the mercuric bromide test paper shall not be darker than the standard.
The standard is to transfer 3.00 mL of arsenic standard solution, add water to 22 mL, and start from "add 5 mL of hydrochloric acid" and treat it in the same way as the sample.
4.11 Determination of loss on ignition
4.11.1 Summary of the method
Ignite the sample at 270-300℃, and determine the loss on ignition based on the reduction before and after ignition. 4.11.2 Instruments and equipment
4.11.2.1 High temperature furnace: can be controlled to work at 270-300℃. 4.11.3 Analysis steps
Weigh about 5g of sample, accurate to 0.0002g, place in a porcelain crucible with constant weight, and burn to constant weight at 270-300℃.
4.11.4 Expression of analysis results
The ignition loss (X.) expressed as mass percentage is calculated according to formula (9): m-ml
-mass of sample after ignition, g;
Where: mr
mass of sample before ignition, g.
4.11.5 Allowable difference
: (9)
Take the arithmetic mean of the parallel determination results as the determination result. The absolute difference between the two parallel determination results shall not exceed 0.05%.
5 Inspection rules
5.1 The food additive potassium carbonate shall be inspected by the quality supervision and inspection department of the manufacturer in accordance with the provisions of this standard. The manufacturer shall ensure that all food additive potassium carbonate shipped from the factory meets the requirements of this standard. Each batch of products shipped shall be accompanied by a quality certificate. The contents include: manufacturer name, product name, batch number, net weight, production date, proof that the product quality meets this standard and the number of this standard. 5.2 The user has the right to inspect and accept the received products in accordance with the provisions of this standard. 5.3 Each batch of products shall not exceed 60t.
5.4 Determine the number of sampling units in accordance with Article 6.6 of GB6678. When sampling, insert the sampler from the vertical center line of the packaging bag to 3/4 of the depth of the material layer to take a sample. After mixing the sample, reduce it to 500g by quartering method, and pack it in two clean and dry wide-mouth bottles and seal them. Stick labels on the bottles, indicating: manufacturer name, product name, batch number, sampling date and name of the sampler. One bottle is used for inspection, and the other bottle is kept for 3 months for future reference.
Approved by the Ministry of Chemical Industry of the People's Republic of China on July 5, 1993, and implemented on January 1, 1994
HG2452-1993
5.5 If one of the indicators in the inspection results does not meet the requirements of this standard, samples should be taken from the packaging bags with twice the amount for re-inspection. If even one indicator in the re-inspection results does not meet the requirements of this standard, the entire batch of products cannot be accepted.
5.6 When the supply and demand parties have objections to the product quality, they shall be handled in accordance with the provisions of the "Interim Measures for National Product Quality Arbitration Inspection".
5.7 During the storage and transportation of food additive potassium carbonate, the ignition loss often increases due to the absorption of moisture or carbon dioxide. When users accept the product weight, the increased ignition loss can be deducted. 6 Marking, packaging, transportation, storage
6.1 The packaging bags of potassium carbonate, a food additive, should have firm and clear markings, including the words "food additive", manufacturer name, product name, production license number, trademark, net weight, batch number or production date and this standard number, as well as the "wet-afraid" mark specified in GB191. 6.2 Potassium carbonate, a food additive, is double-packed. The inner packaging is a food-grade polyethylene plastic film bag with a specification size of 480mm×800mm and a thickness of 0.08mm. The outer packaging is a polypropylene woven bag with a specification size of 460mm×680mm. Its performance and inspection methods should comply with the provisions of GB8946B. The net weight of each bag is 25kg. Ten bags are randomly selected, and the average deviation during weighing should be within 0.2kg. Bulk bag packaging: The flexible bulk bag specified in GB10454 is used. Its specification size, performance and inspection methods should comply with the relevant provisions of GB10454. The net weight of each bag is 1000kg. 6.3 When packaging potassium carbonate as a food additive, the inner packaging bag shall be sealed by heat sealing; the outer bag shall be folded at a distance of not less than 30 mm from the edge, and the opening shall be sewed with vinyl thread or other thread of equivalent quality at a distance of not less than 15 mm from the bag edge. The stitch length shall be 7-12 mm, the stitches shall be neat and uniform, and there shall be no leakage or skipping. 6.4 Potassium carbonate as a food additive shall be covered during transportation to prevent rain, heat, moisture and sun exposure. It shall not be mixed with toxic and hazardous substances. Prevent pollution. 6.5 Potassium carbonate as a food additive shall be stored in a cool, dry and ventilated warehouse to prevent heat, moisture, mixed storage with toxic and hazardous substances and prevent pollution. Additional remarks:
This standard was proposed by the Science and Technology Department of the Ministry of Chemical Industry of the People's Republic of China. This standard is under the jurisdiction of Tianjin Chemical Research Institute of the Ministry of Chemical Industry and Food Hygiene Supervision and Inspection Institute of the Ministry of Health. This standard was drafted by Tianjin Chemical Research Institute of the Ministry of Chemical Industry and Chengdu Chemical Plant of Sichuan Province. The main drafters of this standard are: Liu Shuying, Shi Jie, Wang Youkun, Yang Qianshuang. This standard adopts the fifth edition (86) of the "Japanese Food Additives Code" "Potassium Carbonate". Approved by the Ministry of Chemical Industry of the People's Republic of China on July 5, 1993 and implemented on January 1, 19944 Potassium carbonate, a food additive, should be covered during transportation to prevent it from rain, heat, moisture and sunlight. It should not be transported together with toxic and hazardous substances. Prevent contamination. 6.5 Potassium carbonate, a food additive, should be stored in a cool, dry and ventilated warehouse to prevent it from heat, moisture, and mixing with toxic and hazardous substances to prevent contamination. Additional notes:
This standard was proposed by the Science and Technology Department of the Ministry of Chemical Industry of the People's Republic of China. This standard is under the jurisdiction of the Tianjin Chemical Research Institute of the Ministry of Chemical Industry and the Food Hygiene Supervision and Inspection Institute of the Ministry of Health. This standard was drafted by the Tianjin Chemical Research Institute of the Ministry of Chemical Industry and Chengdu Chemical Plant of Sichuan Province. The main drafters of this standard are: Liu Shuying, Shi Jie, Wang Youkun and Yang Qianshuang. This standard refers to the fifth edition of the "Japanese Food Additive Code" (86) "Potassium Carbonate". Approved by the Ministry of Chemical Industry of the People's Republic of China on July 5, 1993 and implemented on January 1, 1994
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