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GB 22215-2008: Food additive sodium hydrosulfite
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Food additive sodium hydrosulfite
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GB 22215-2008
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Basic data | Standard ID | GB 22215-2008 (GB22215-2008) | | Description (Translated English) | Food additive sodium hydrosulfite | | Sector / Industry | National Standard | | Classification of Chinese Standard | X42 | | Classification of International Standard | 67.220.20 | | Word Count Estimation | 12,164 | | Date of Issue | 2008-06-25 | | Date of Implementation | 2009-01-01 | | Quoted Standard | GB 190-1990; GB/T 191-2008; GB/T 5009.15-2003; GB/T 5009.75-2003; GB/T 5009.76-2003; GB/T 6678; GB/T 6682-2008; HG/T 3696.1; HG/T 3696.2; HG/T 3696.3 | | Regulation (derived from) | Announcement of Newly Approved National Standards No. 12 of 2008 (No. 125 overall) | | Issuing agency(ies) | General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China, Standardization Administration of the People's Republic of China | | Summary | This Chinese standard specifies the food additive sodium dithionite requirements, test methods, inspection rules, marking, labeling, packaging, transportation and storage. This standard applies to food additives sodium dithionite. The product as a preservative in food processing, bleaching agents, anti- oxidants. | GB 22215-2008: Food additive sodium hydrosulfite---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.
Food additive sodium hydrosulfite
ICS 67.220.20
X42
National Standards of People's Republic of China
Food Additives
Sodium dithionite (hydrosulfite)
Posted 2008-06-25
2009-01-01 implementation
Administration of Quality Supervision, Inspection and Quarantine of People's Republic of China
Standardization Administration of China released
Foreword
The standard Chapter 4 and Chapter 7 are mandatory, others are recommended.
This standard Japanese food Kimisada Book (2000 edition) "hydrosulfite (sodium dithionite)" non-equivalent.
The standard proposed by China Petroleum and Chemical Industry Association.
This standard by the National Standardization Technical Committee chemical inorganic chemicals Club (SAC/TC63/SC1) and the National Food Additives Standardization
Technical Committee (SAC/TC11) common focal point.
This standard was drafted. Tianjin Chemical Engineering Research and Design Institute, Shandong Gold River Industrial Co., Ltd. Guangdong Zhongcheng Chemicals.
The main drafters of this standard. Zhaomei Jing, Wang Guoqing, Deng key Zhangbao Jian.
The standard standard replaces the previous editions.
--- First released as the national standard GB 1647 - 1979, 1995 Adjustment for the chemical industry standard HG2682-1995.
Food Additives
Sodium dithionite (hydrosulfite)
1 Scope
This standard specifies the food additive sodium dithionite (low sodium sulfite, sodium hydrosulfite) requirements, test methods, inspection rules, marking
Chi, labeling, packaging, transportation and storage.
This standard applies to food additive sodium dithionite (low sodium sulfite, sodium hydrosulfite). The product as a preservative in food processing,
Bleaching agents, antioxidants.
2 Normative references
The following documents contain provisions which, through reference in this standard and become the standard terms. For dated references, subsequent
Amendments (not including errata content) or revisions do not apply to this standard, however, encourage the parties to the agreement are based on research
Study whether the latest versions of these documents. For undated reference documents, the latest versions apply to this standard.
GB 190-1990 dangerous goods packaging logo
GB/T 191-2008 Packaging - Pictorial signs (ISO 780.1997, MOD)
GB/T 5009.15-2003 Determination of cadmium in food
Determination of GB/T 5009.75-2003 food additives lead
Determination of GB/T 5009.76-2003 arsenic in food additives
GB/T 6678 General Principles for Sampling Chemical Products
GB/T 6682-2008 analytical laboratory use specifications and test methods (ISO 3696. 1987, MOD)
Preparation of standard titration solution of HG/T 3696.1 inorganic chemical products, chemical analysis
Preparation of HG/T 3696.2 inorganic chemical products, chemical analysis of impurity standard solution
Preparations of HG/T 3696.3 inorganic chemical products, chemical analysis
3 formula, molecular weight
Molecular formula. Na2S2O4
Molecular weight. 174.11 (according to 2007 international relative atomic mass)
4 Requirements
4.1 Appearance. white crystalline powder.
4.2 Food additive sodium dithionite (hydrosulfite) shall comply with the requirements of Table 1.
Table 1 Requirements
Item Index
Sodium dithionite (Na2S2O4), /% ≥ 88.0
Clarity through test
Heavy metals (Pb), /% ≤ 0.001
Lead (Pb), /% ≤ 0.0005
Cadmium (Cd), /% ≤ 0.0002
Table 1 (continued)
Item Index
Arsenic (As), /% ≤ 0.0001
Edetate disodium (EDTA), /% qualified
Zinc (Zn), /% ≤ 0.03a
Formate (in terms HCHO), /% ≤ 0.05b
a sodium formate process production of food additive sodium dithionite (hydrosulfite) does not control the zinc content of the index.
b In zinc process production of food additive sodium dithionite (hydrosulfite) does not control the content of the index formate.
5 Test methods
5.1 Safety Tips
Reagents used in this test method are toxic or corrosive, be careful when operating! Such as water splashed on the skin should immediately
Flushing, severe cases should be treated immediately.
5.2 General Provisions
This standard reagents and water, did not indicate when the other requirements, refer to analytically pure reagents and GB/T 6682-2008 stipulated three
Grade water. 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.
5.3 appearance of discrimination
In natural light, determined by visual appearance.
5.4 Identification Test
5.4.1 Reagents
5.4.1.1 hydrochloric acid solution. 1 + 1;
5.4.1.2 copper sulfate. 50g/L;
5.4.1.3 potassium permanganate solution. 3.5g/L;
5.4.1.4 Coke antimony potassium solution;
Weigh 2g antimony potassium pyrophosphate, add 100mL water dissolved, boil for about 5min, rapid cooling, 10mL of sodium hydroxide solution, place
24h after filtration.
5.4.2 Identification Methods
5.4.2.1 Identification even dithionite
a) Take 10mL10g/L test solution, add 2mL when copper sulfate solution, which was gray and black.
b) Take 10mL10g/L test solution, potassium permanganate solution is added 1mL, the color of the solution disappears.
5.4.2.2 Identification of the sodium salt
a) Take a platinum wire dipped hydrochloric acid till colorless, remarriage take 10g/L test solution in the alcohol lamp burning yellow.
b) take appropriate 50g/L test solution is added antimony potassium pyrophosphate solution, a white crystalline precipitate (when the test tube with a glass rod friction wall,
Can accelerate the generation of precipitation).
5.5 Determination of sodium hydrosulfite even Contents
5.5.1 Method summary
Sodium dithionite and neutral formaldehyde, generating formaldehyde and sodium bisulfite, sodium formaldehyde sulfoxylate, sodium sulfoxylate formaldehyde and hydrogen iodide as
Used to determine the content of dithionite that the consumption of iodine standard titration solution.
5.5.2 Reagents
5.5.2.1 hydrochloric acid solution. 1 + 11;
5.5.2.2 neutral formalin solution. 1 + 1;
Take formaldehyde solution 100mL and 100mL water, placed in 400mL beaker, stir, a few drops of 10g/L phenolphthalein indicator solution, with
100g/L of sodium hydroxide solution and to the solution was reddish, then reddish hydrochloric acid solution was adjusted to just fade.
5.5.2.3 soluble starch solution. 10g/L.
5.5.2.4 Iodine Standard Solution. Ba 12I () 2 ≈0.1mol/L.
5.5.3 Analysis of step
Weigh about 1g sample, accurate to 0.0002g, placed in a pre beaker 20mL neutral formalin solution, stirring until completely dissolved
Solutions for all transferred to 250mL volumetric flask, dilute to the mark, shake. Pipette 25mL of this solution in 250mL conical flask, add
4mL hydrochloric acid solution, titration with iodine standard solution titration, was added near the end 3mL starch solution and continue titration until the solution was light blue in
It does not disappear shall end within 30s. While the same treatment the blank test solution.
5.5.4 Calculation Results
Dithionite content of sodium dithionite (Na2S2O4) mass fraction of 1 meter, expressed in%, according to equation (1).
1 =
[(Vp - V0)/1000] Ba M
100 (1)
Where.
Numerical iodine standard titration solution volume Vp --- titration solution consumed in milliliters (mL);
Numerical iodine standard titration solution volume V0 --- blank test consumed in milliliters (mL);
--- Accurate Ba concentration of iodine standard titration value in units of moles per liter (mol/L);
--- The M sodium dithionite 14Na2S2O () value of 4 molar mass in grams per mole (g/mol) (M = 43.53).
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 0.5%.
5.6 Determination of Clarity
5.6.1 Method summary
The dithionite dissolved in neutral formaldehyde solution, in the case of direct sunlight, and by observing the sodium dithionite solution
Insolubles content was determined to clarity.
5.6.2 instruments and equipment
5.6.2.1 neutral formalin solution. 1 + 1 (with 5.5.2.2);
5.6.2.2 nitric acid solution. 1 + 2;
5.6.2.3 dextrin solution [(C6H10O5) * x0 like H2O]. 20g/L;
5.6.2.4 silver nitrate solution. 20g/L;
5.6.2.5 hydrochloric acid standard solution. Ba (HCl) ≈0.1mol/L;
5.6.2.6 Chloride Standard solution. 1mL solution of chlorine (Cl) 0.010mg;
Pipette 1.00mL chloride standard solution according to HG/T 3696.2 requirements formulated, placed in 100mL volumetric flask, dilute with water to
Mark and shake. The solution is using now.
5.6.3 Analysis of step
5.6.3.1 Preparation of standard reference solution (slightly cloudy) of
Pipette Pipette 6mL chloride standard solution, placed in 25mL colorimetric tube, add water to about 20mL, nitric acid solution is added 1mL
Diluent, 0.2mL 1mL dextrin solution and silver nitrate solution with water to the mark. Placed in the case to avoid direct sunlight
15min.
5.6.3.2 Determination
Weigh 0.50g ± 0.01g sample was placed in a pre-filled with neutral formaldehyde solution 25mL 10mL colorimetric tube, completely dissolved, with
Diluted with water to the mark. Place 5min, in the absence of direct sunlight, observed from the top down, the turbidity of the test solution is not greater than the standard
Nephelometric turbidity shown solution.
Note. During the test, should control standards and test solution was placed 15min turbidimetric solution simultaneously placed 5min point.
5.7 Determination of Heavy Metal Content
5.7.1 Method summary
In weakly acidic solution of heavy metal ions and divalent sulfur ions to form a colored sulfide precipitation, low heavy metal content, generate stable
Dark suspensions, for visual colorimetric determination of heavy metals.
5.7.2 Reagents
5.7.2.1 hydrochloric acid;
5.7.2.2 acetic acid solution. 1 + 19;
5.7.2.3 sodium sulfide solution;
5.7.2.4 Lead standard solution. 1mL solution containing lead (Pb) 0.010mg;
Pipette 1.00mL lead standard solution according to HG/T 3696.2 requirements formulated, placed in 100mL volumetric flask, dilute to the mark,
Shake well. The solution is using now.
5.7.3 Analysis of step
5.7.3.1 Preparation of test solution A
Weigh 10.00g ± 0.01g sample was placed in 300mL beaker, add water to dissolve 60mL, 10mL hydrochloric acid plus adjustable electric
On evaporated to dryness. Carefully heat to strengthen the spontaneous combustion of sulfur. To the residue was added 30mL water and 10mL of hydrochloric acid, and then evaporated to an electric furnace in an adjustable
dry. The residue was dissolved in water and diluted with water to about 30mL, filtered and the filtrate and washings were placed in 50mL volumetric flask, dilute with water to
Mark and shake. This solution as the test solution A. This solution was used to determine the content of heavy metals (5.7), determination of lead in dithizone colorimetric
Method (5.8.1), Determination of cadmium content in the colorimetric method (5.9.2) and zinc content in visual colorimetry (5.12.2).
5.7.3.2 Determination
Pipette Pipette 10mL test solution A (5.7.3.1), placed in 50mL colorimetric tube, add 2mL acetic acid solution, a solution of 2 drops
Sodium sulfide solution was diluted with water to the mark. After standing 5min, the color of the test solution must not be darker than the standard colorimetric solution.
Standard colorimetric solution is lead standard solution Pipette 2.00mL, placed 50mL colorimetric tube, add 2mL acetic acid solution, and the test solution
Liquid while the same treatment.
5.8 Determination of lead content
5.8.1 dithizone colorimetry (Arbitration Act)
5.8.1.1 Warning. Some solution and reagents used in this chapter for human health, should avoid inhalation or contact with the skin, using a solution or test
Operations agent shall be conducted in a fume hood.
5.8.1.2 Method summary
After adding the sample treated ammonium citrate, potassium cyanide and hydroxylamine hydrochloride, etc., to eliminate iron, copper, zinc ion interference at pH 8.5 ~
9.0, the lead dithizone ions to form a red complex, extracted with chloroform, compared with standard series for quantitative tests.
5.8.1.3 Reagents
With GB/T 5009.75-2003 Chapter 3.
5.8.1.4 Instruments
With GB/T 5009.75-2003 Chapter 4.
5.8.1.5 analysis step
Pipette 10mL test solution A (5.7.3.1), placed in a separatory funnel. The following according to GB/T 5009.75-2003 provisions of Chapter 6
Measured.
5.8.2 atomic absorption spectrophotometry
5.8.2.1 Method summary
The treated sample, the absorbance was measured in the atomic absorption spectrometer. Within a certain range of concentrations of lead content into its absorbance
It is proportional.
5.8.2.2 Reagents
5.8.2.2.1 hydrogen peroxide;
5.8.2.2.2 nitrate solution. 1 + 1;
5.8.2.2.3 hydrochloric acid solution. 1 + 4;
5.8.2.2.4 Lead standard solution. 1mL solution containing lead (Pb) 0.03mg;
Pipette 3.00mL lead standard solution according to HG/T 3696.2 requirements formulated, placed in 100mL volumetric flask, dilute to the mark,
Shake well. The solution is using now.
5.8.2.2.5 Water. Water line with two GB/T 6682-2008 requirements.
5.8.2.3 Instruments
5.8.2.3.1 atomic absorption spectrophotometer.
5.8.2.4 analysis step
5.8.2.4.1 Preparation of the sample solution B
Weigh about 5g samples, accurate to 0.0002g, placed in 200mL beaker high type, add water wet, add 50mL nitric acid solution in
Electric furnace heated to boiling, with a dropper carefully and slowly along the hydrogen peroxide was added dropwise 6mL ~ 10mL beaker wall, heating was continued to near dryness on a hot plate, cold
but. All transferred to 100mL volumetric flask, dilute to the mark, shake. This solution as the test solution B. The solution for lead content
Determination of atomic absorption spectrophotometry (5.8.2), the determination of cadmium content by atomic absorption spectrophotometry (5.9.1), Determination of zinc content in
Atomic absorption spectrophotometry (5.12.1).
5.8.2.4.2 Draw the curve
Pipette respectively Pipette 0.00mL, 1.00mL, 2.00mL, 4.00mL, 6.00mL lead standard solution, placed five 100mL
Flask, add 5mL hydrochloric acid solution, diluted with water to the mark. Acetylene - air flame, the original wavelength at 283.3nm
Sub absorption spectrophotometer adjusted to the best working condition, zero water, absorbance was measured. From the absorbance of each standard solution subtracting the blank solution
Absorbance of liquid to the quality of the lead as the horizontal, the vertical axis corresponding to the absorbance, drawing working curve.
5.8.2.4.3 Determination
Acetylene - air flame, at a wavelength of 283.3nm at the atomic absorption spectrophotometer to an optimal working condition, zero water, measuring
The amount of test solution B (5.8.2.4.1) absorbance. While the same treatment the blank test solution. Isolated from the working curve corresponding lead
quality.
5.8.2.5 Calculation Results
Lead content of lead (Pb) mass fraction 2 and its value is expressed in%, according to equation (2).
2 =
(2)
Where.
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 0.0002%.
5.9 Determination of cadmium content
5.9.1 atomic absorption spectrophotometry (Arbitration Act)
5.9.1.1 Method summary
The treated sample, the absorbance was measured in the atomic absorption spectrometer. Within a certain range of concentrations of cadmium content into its absorbance
It is proportional.
5.9.1.2 Reagents
5.9.1.2.1 hydrochloric acid solution. 1 + 4;
5.9.1.2.2 cadmium standard solution. 1mL solution containing cadmium (Cd) 0.01mg;
Pipette 1.00mL cadmium standard solution according to HG/T 3696.2 requirements formulated, placed in 100mL volumetric flask, dilute to the mark,
Shake well. The solution is using now.
5.9.1.2.3 Water. Water line with two GB/T 6682-2008 requirements.
5.9.1.3 Instruments
5.9.1.3.1 atomic absorption spectrophotometer.
5.9.1.4 analysis step
5.9.1.4.1 Draw the curve
Pipette were pipetted 0.00mL, 1.00mL, 2.00mL, 3.00mL standard cadmium solution, placed in 100mL flasks 4
Added 5mL hydrochloric acid solution, diluted with water to the mark. Acetylene - air flame, at a wavelength of 228.8nm at the atomic absorption
Spectrophotometer adjusted to the best working condition, zero water, absorbance was measured. Subtracting the blank solution sucked from the absorbance of each standard solution
Luminosity, quality cadmium as the horizontal, the vertical axis corresponding to the absorbance, drawing working curve.
5.9.1.4.2 Determination
Acetylene - air flame, at a wavelength of 228.8nm at the atomic absorption spectrophotometer to an optimal working condition, zero water, measuring
The amount of test solution B (5.8.2.4.1) absorbance. While the same treatment the blank test solution. Isolated from the working curve of the corresponding cadmium
quality.
5.9.1.5 Calculation Results
Cadmium content of cadmium (Cd) mass fraction 3 and its value is expressed in%, according to equation (3) Calculated.
3 =
(3)
Where.
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 0.0002%.
5.9.2 Colorimetric
5.9.2.1 Method summary
After the sample was treated in alkaline solution cadmium ions react with 6-bromo Benzothiazoleazo naphthol form a red complex, dissolved in chloroform, and
Comparison of standard series.
5.9.2.2 Reagents
With GB/T 5009.15-2003 Chapter 21.
5.9.2.3 Instruments
With GB/T 5009.15-2003 Chapter 22.
5.9.2.4 analysis step
Pipette 10mL test solution A (5.7.3.1), the following according to GB/T 5009.15-2003 Determination of the provisions of Chapter 23.2.
5.9.2.5 Calculation Results
With GB/T 5009.15-2003 Chapter 24.
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 0.0002%.
Determination of Arsenic 5.10
5.10.1 Method summary
With GB/T 5009.76-2003 Chapter 8.
5.10.2 Reagent
5.10.2.1 arsenic standard solution. 1mL solution containing arsenic (As) 1μg;
Pipette 1.00mL arsenic standard solution according to HG/T 3696.2 requirements formulated placed 1000mL volumetric flask, dilute to the mark with water
Degree, shake. The solution is using now.
5.10.2.2 Other reagents with GB/T 5009.76-2003 Chapter 9.
5.10.3 instruments and equipment
With GB/T 5009.76-2003 Chapter 10.
5.10.4 analysis step
Weigh 5.00g ± 0.01g sample was placed in 100mL beaker, dissolved in water, all transferred to a 50mL volumetric flask, diluted with water
To the mark.
Pipette 5mL above test solution was placed in 100mL beaker, add 1mL of sulfuric acid, all transferred to measure arsenic bottle, add 4mL hydrochloric acid,
Following in the GB/T 5009.76-2003 Chapter 11, "add water to 30mL" were determined. Gutzeit mercuric bromide paper that was
No deeper than the standard colors.
Standard colorimetric solution is a standard solution Pipette 0.50mL of arsenic, arsenic placed in measuring flask, 5mL hydrochloric acid, simultaneously with the same sample
deal with.
5.11 Determination of the content of disodium edetate
5.11.1 Method summary
Arsenite the chromium ion is reduced to chromium ions, chromium ions and ethylenediaminetetraacetic acid disodium generate violet complex that can be used edetate
Disodium test.
5.11.2 Reagent
5.11.2.1 acetic acid;
5.11.2.2 Potassium chromate solution. 5g/L;
5.11.2.3 sodium hydroxide solution. 25g/L;
5.11.2.4 arsenite solution. 10g/L;
Weigh 1g arsenite (arsenic trioxide), sodium hydroxide solution was added 30mL, heated and dissolved. After cooling, acetic acid was slowly added to with
100mL.
5.11.3 analysis step
Weigh 0.50g ± 0.01g sample was placed in a test tube, add 5mL dissolved in water, add 2mL potassium chromate solution, 2mL arsenite solution
Was heated in a water bath was purple 2min not qualified.
5.12 Determination of zinc content
5.12.1 atomic absorption spectrophotometry (Arbitration Act)
5.12.1.1 Method summary
The treated sample, the absorbance was measured in the atomic absorption spectrometer. In a certain concentration range, the zinc content into its absorbance
It is proportional.
5.12.1.2 Reagents
5.12.1.2.1 hydrochloric acid solution. 1 + 4;
5.12.1.2.2 Zinc standard solution. 1mL solution of zinc (Zn) 0.05mg;
Pipette 5.00mL zinc standard solution according to HG/T 3696.2 requirements formulated, placed in 100mL volumetric flask, dilute to the mark,
Shake well. The solution is valid for one month.
5.12.1.2.3 water. meet the two water GB/T 6682-2008 requirements.
5.12.1.3 Instruments
5.12.1.3.1 atomic absorption spectrophotometer.
5.12.1.4 measuring step
Draw the curve 5.12.1.4.1
Pipette were pipetted 0.00mL, 1.00mL, 2.00mL, 3.00mL standard zinc solution was placed in 100mL flasks 4
Added 5mL hydrochloric acid solution, diluted with water to the mark. Acetylene - air flame, at a wavelength of 213.8nm at the atomic absorption
Spectrophotometer adjusted to the best working condition, zero water, absorbance was measured. Subtracting the blank solution sucked from the absorbance of each standard solution
Luminosity, quality zinc as the horizontal, the vertical axis corresponding to the absorbance, drawing working curve.
5.12.1.4.2 Determination
Pipette with a pipette 5mL of test solution B (5.8.2.4.1), placed in 100mL volumetric flask, was added 5mL hydrochloric acid solution, diluted with water
Release to the mark. The following press 5.12.1.4.1 From "acetylene - air flame, the absorbance is measured" in operation. While at the same
Li blank test solution. Isolated appropriate quality zinc from the working curve.
5.12.1.5 Calculation Results
Zinc content of zinc (Zn) mass fraction 4 and its value is expressed in%, according to equation (4) Calculated.
4 =
100 (4)
Where.
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 0.002%.
5.12.2 visual colorimetry
5.12.2.1 Method summary
In acidic medium, the zinc ions and potassium ferrocyanide solution, a white precipitate, zinc can be used for visual colorimetric method.
5.12.2.2 Reagents
5.12.2.2.1 ammonia solution. 2 + 3;
5.12.2.2.2 hydrochloric acid solution. 1 + 3;
5.12.2.2.3 potassium ferrocyanide solution. 100g/L;
Weigh 10g of potassium ferrocyanide, accurate to 0.01g, diluted with water to 100mL, the solution is using now.
5.12.2.2.4 Zinc standard solution. 1mL solution containing zinc (Zn) 0.10mg;
Pipette 10.00mL zinc standard solution according to HG/T 3696.2 requirements formulated, placed in 100mL volumetric flask, dilute to the mark with water
Degree, shake.
5.12.2.3 analysis step
Pipette with a pipette 5mL test solution A (5.7.3.1), a 50mL beaker was added 0.1mL aqueous ammonia solution, filtered and the filtrate
Add 25mL colorimetric tube, dilute with water to 20mL, plus 5mL hydrochloric acid solution, shake, add 0.1mL solution of potassium ferrocyanide, place
15min, turbidity shall not exceed the standard turbidity solution.
Turbidity standard solution with a pipette Pipette 3.00mL zinc standard solution, placed in 25mL colorimetric tube from the "diluted with water to 20mL
"Began to operate, while the same treatment with the test solution.
Determination of formate content of 5.13
5.13.1 Method summary
In the medium of hydrochloric acid, magnesium formate will be reduced to formaldehyde, formaldehyde and chromium sour reaction effects occur, it can be used for visual colorimetric formate
Determination.
5.13.2 Reagent
5.13.2.1 magnesium;
5.13.2.2 sulfuric acid;
5.13.2.3 hydrochloric acid solution. 1 + 1;
5.13.2.4 chromotropic acid solution (C10H6Na2S2O8 · 2H2O). 10g/L;
Weigh 0.5g chromotropic acid, sulfuric acid plus 50mL shake mix, centrifuged, the supernatant use, Extemporaneous.
5.13.2.5 formaldehyde standard solution. 1mL solution containing formaldehyde (HCHO) 0.0020mg;
Pipette 2.00mL formaldehyde standard solution according to HG/T 3696.2 requirements formulated placed 1000mL volumetric flask, dilute with water to
Mark and shake. The solution is using now.
5.13.3 analysis step
Weigh 0.100g ± 0.001g sample placed in 100mL flask, diluted with water to the mark. Pipette pipette 10mL
The solution was placed in a beaker, was added 5mL hydrochloric acid solution, then add a small amount of magnesium twice, adding to about 0.3g, almost no bubbles
After surface covered dish, placed 2h. All were transferred to 50mL colorimetric tube, add 2mL of...
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