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GB 1897-2008: Food additive -- Hydrochloric acid
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Food additive -- Hydrochloric acid
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Basic data | Standard ID | GB 1897-2008 (GB1897-2008) | | Description (Translated English) | Food additive -- Hydrochloric acid | | Sector / Industry | National Standard | | Classification of Chinese Standard | X42 | | Classification of International Standard | 67.220.20 | | Word Count Estimation | 15,187 | | Date of Issue | 2008-06-25 | | Date of Implementation | 2009-01-01 | | Older Standard (superseded by this standard) | GB 1897-1995 | | Quoted Standard | GB 190-1990; GB/T 191-2008; GB/T 601-2002; GB/T 602-2002; GB/T 603-2002; GB 2760-1996; GB/T 6678-2003; GB/T 6682-2003; GB/T 6682-2008 | | Adopted Standard | FCC (V)-2004, NEQ | | 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 requirements for food additives, hydrochloric acid, test methods, inspection rules and signs, labels, packaging, transport and storage. This standard applies to chlorine and hydrogen absorption by the water obtained synthetic food additives hydrochloric acid. The product is used in food processing as acidity regulator and the food industry processing aids. | GB 1897-2008: Food additive -- Hydrochloric acid---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.Hydrochloric acid
ICS 67.220.20
X42
National Standards of People's Republic of China
Replacing GB 1897-1995
Food additives hydrochloride
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 and the United States "Food Chemicals Codex with the" fifth edition [FCC (V).2004] degree of consistency "hydrochloric acid" is not equivalent.
This standard replaces GB 1897-1995 "food additive hydrochloric acid."
This standard and GB 1897-1995 main technical differences compared as follows.
--- Technical indicators improve iron (3.2 the previous version, this version 4.2);
--- Residue on ignition canceled projects, increase non-volatile items (before version 3.2, this version 4.2);
--- Cancel the determination of residue on ignition method to increase the non-volatile matter measuring method (before version 4.7, this version 5.10);
--- Increased under special circumstances and the type test cycle should type inspection requirements (edition 6.2).
The standard proposed by China Petroleum and Chemical Industry Association.
This standard by the National Standardization Technical Committee of the inorganic chemistry branch (SAC/TC63/SC1) and the National Food Additives Standardization
Committee (SAC/TC11) centralized.
This standard was drafted. Hangzhou Electrochemical Group Co., Jinxi Chemical Industry Research Institute, Yunnan Salt & Chemical Co., Ltd., Haohua Yuhang Chemical
Co., Ltd., Tianjin Dagu Chemical Co., Ltd., Shanghai Chlor-Alkali Chemical Co., Ltd., Qingdao Haijing Chemical Group Co., Ltd.
The main drafters of this standard. Chenpei Yun, Jiangyue Fang, Li Furong, Wu Rong right, Liu Zhiqiang, Chen Shao copper, Caojian Fang, Zhang Yingmin.
This standard was first released in 1986, 1995 and the first amendment.
Food additives hydrochloride
Warning --- hydrochloric acid is highly corrosive, the operator should take appropriate safety and health measures, the contact should wear protective glasses, acid-hand
Sets and other protective equipment.
1 Scope
This standard specifies the requirements for food additives hydrochloric acid, test methods, inspection rules and signs, labels, packaging, transport and storage.
This standard applies to the synthesis of chlorine and hydrogen by the water absorption obtained food additive hydrochloric acid. The product as acidity regulator in food processing
Agents and food processing industry with aids.
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 Storage icon flag (ISO 780.1997, MOD)
Preparation of GB/T 601-2002 Chemical Reagent standard titration solution
GB/T 602-2002 Chemical Reagent Determination of impurities in the preparation of standard solution used
GB/T 603-2002 Chemical Reagent Test Methods - Preparations with
GB 2760-1996 Hygienic standards for uses of food additives
GB/T 6678-2003 General rules for sampling chemical products
GB/T 6680-2003 General rules for sampling liquid chemical products
GB/T 6682-2008 analytical laboratory use specifications and test methods (ISO 3696. 1987, MOD)
3 formula and relative molecular mass
Molecular formula. HCl
Molecular Weight. 36.46 (according to 2007 international relative atomic mass)
4 Requirements
4.1 Appearance. colorless or light yellow transparent liquid.
4.2 Food additives shall comply with the requirements of Table 1 hydrochloric acid.
Table 1 requires%
Item Index
Total acidity (based on HCl), ≥ 31.0
Iron (as Fe), ≤ 0.0005
Sulfate (SO2-4 dollars), ≤ 0.007
Free chlorine (Cl to count), ≤ 0.003
Reducing substances (in terms SO3), ≤ 0.007
Non-volatile matter, ≤ 0.05
Heavy Metals (as Pb), ≤ 0.0005
Arsenic (As), ≤ 0.0001
5 Test methods
5.1 Safety Tips
This test method Reagents toxic or corrosive, be careful when operating! As splashed on the skin should immediately wash with water, Yan
In severe cases should be treated immediately.
5.2 General Provisions
This standard reagents and water, did not indicate when the other requirements, refer to three analytical reagent and GB/T 6682-2008 specified
water. Used in the test standard titration solution, impurity standard solution, preparations and products, did not indicate when the other requirements, according to GB/T 601-
2002, GB/T 602-2002, regulations preparation GB/T 603-2002 in.
5.3 Identification
5.3.1 Reagents and solutions
5.3.1.1 silver nitrate solution. 2g/L.
5.3.1.2 ammonia solution. 2 + 3.
5.3.1.3 methyl orange indicator solution. 1g/L.
5.3.2 Identification Methods
5.3.2.1 1mL weighed sample in 50mL water, was added dropwise a solution of silver nitrate, i.e., a white milky precipitate. It can be dissolved in ammonia solution,
Insoluble in nitric acid.
5.3.2.2 amount of 1mL sample in 100mL of water, add 2 drops of methyl orange solution, the solution turns red, the aqueous solution is strongly acidic.
5.3.3 Identification Conclusion
More than two tests give a positive response, it can determine if this sample is hydrochloric acid.
5.4 Appearance
In natural light visually observed.
5.5 Determination of total acidity
5.5.1 Principle of the method
The sample solution is bromocresol green indicator solution, titration with sodium hydroxide standard solution titration solution from yellow to blue as the end point. anti-
Should the formula.
H ++ OH → - H2O
5.5.2 Reagents and solutions
5.5.2.1 sodium hydroxide standard titration solution. Ba (NaOH) = 1mol/L.
5.5.2.2 bromocresol green indicator solution. 1g/L.
5.5.3 Instruments
General laboratory equipment and the following container.
5.5.3.1 Erlenmeyer flask, 100mL (with ground glass stopper).
5.5.3.2 Buret, 50mL, A-level, there is 0.1mL division value.
5.5.4 Analysis of step
5.5.4.1 Sample
Weighed about 3mL sample and put the contents of about 15mL of water and has weighed (accurate to 0.0001g) Erlenmeyer flask, mix and weighed (fine
Accurate to 0.0001g).
5.5.4.2 Determination
To add the Samples (2-3) drops of bromocresol green indicator solution, titration with sodium hydroxide standard titration solution until the solution changed from yellow to blue
end.
5.5.5 Calculation Results
The total acidity of hydrogen chloride (HCl) mass fraction of 1 meter, expressed in%, according to equation (1).
1 =
(Vp/1000) Ba M
(1)
Where.
Accurate Ba --- sodium hydroxide standard titration solution concentration value in units of moles per liter (mol/L);
Numerical sodium hydroxide standard titration Vp --- titration solution consumed volume in milliliters (mL);
Numerical --- the M hydrogen chloride (HCl) molar mass in grams per mole (g/mol) (M = 36.46).
5.5.6 allowable difference
Take the arithmetic mean of the parallel determination results of the measurement results, the results of parallel determination of the absolute difference is not more than 0.2%.
5.6 Determination of iron content - 1,10-phenanthrene spectrophotometry method
5.6.1 Principle of the method
Hydroxylamine with hydrochloric acid in a sample Fe3 + is reduced to Fe2 +, at pH 4.5 buffer solution system, Fe2 + and 1,10-phenanthrene morpholino reaction product
Into the orange-red complex, the absorbance was measured using a spectrophotometer. Reaction is as follows.
4Fe3 ++ 2NH2 → OH 4Fe2 ++ N2O + 4H ++ H2O
Fe2 ++ 3C12H8N → 2 [Fe (C12H8N2) 3] 2+
5.6.2 Reagents and solutions
5.6.2.1 hydrochloric acid solution. 1 + 10.
5.6.2.2 ammonia solution. 1 + 1.
5.6.2.3 hydroxylamine hydrochloride solution. 100g/L.
Weigh 10.0g of hydroxylamine hydrochloride, dissolved in water and diluted with water to 100mL.
5.6.2.4 acetic acid - sodium acetate buffer solution. pH≈4.5.
5.6.2.5 Iron standard solution. 1mL solution containing iron (Fe) 0.1mg.
Weigh 0.864g of ammonium ferric sulfate [NH4Fe (SO4) 2 · 12H2O], dissolved in water, add 10mL sulfuric acid solution (25%), moved
1000mL volumetric flask, dilute to the mark.
5.6.2.6 Iron standard solution. 1mL solution containing iron (Fe) 0.01mg.
Using a pipette, said iron standard solution of 10mL placed in 100mL flask, diluted with water to the mark. The solution now
With the existing service.
5.6.2.7 1,10- Philippines morpholino solution. 2g/L.
The solution should be stored in the dark, using only colorless solution.
5.6.3 Instruments
General laboratory equipment and a spectrophotometer.
5.6.4 Analysis of step
5.6.4.1 Standard curve drawing
5.6.4.1.1 Table 2. The amount of iron standard solution (5.6.2.6) were placed six 50mL volumetric flask.
Table 2
Iron standard solution volume/mL corresponding iron mass/μg
00
2.0 20
4.0 40
6.0 60
8.0 80
10.0 100
5.6.4.1.2 To each flask was added 10mL of hydrochloric acid solution, add water to approximately 20mL, with aqueous ammonia solution is adjusted to pH 2-3,
Followed by hydroxylamine hydrochloride solution is added 1mL, 5mL of acetic acid - sodium acetate buffer solution and diluted 2mL1,10- Philippines morpholino solution with water to
Mark and shake. Stand for 15min.
5.6.4.1.3 with a suitable cuvette, at a wavelength of 510nm at zero spectrophotometer with the blank solution adjustment, assay solution absorbance.
5.6.4.1.4 iron content (μg) as abscissa and the corresponding absorbance for the vertical axis of the standard curve or calculate a linear regression
equation.
5.6.4.2 Preparation of sample solution
Weighed about 8.6mL sample weighed (accurate to 0.01g), placed in a built about 50mL water 100mL flask, diluted with water to
Mark and shake.
5.6.4.3 Sample
Amount of 10.0mL sample solution was placed in 50mL volumetric flask.
5.6.4.4 blank test
Without the sample, add 10.0mL hydrochloric acid solution, using the same sample and determination of the analytical procedure, and the amount of reagent blank
test.
5.6.4.5 Determination
5.6.4.5.1 Water was added to the test samples to about 20mL, with aqueous ammonia solution is adjusted to pH 2-3, and then add 1mL hydroxylamine hydrochloride solution,
5mL of acetic acid - sodium acetate buffer solution and 2mL1,10- Philippines morpholino solution was diluted with water to the mark. Stand for 15min.
5.6.4.5.2 with a suitable cuvette, at a wavelength of 510nm at zero spectrophotometer with the blank solution adjustment, assay solution absorbance.
5.6.5 Calculation Results
Iron content of iron (Fe) mass fraction 2 and its value is expressed in%, according to equation (2).
-6
-3
(2)
Where.
5.6.6 allowable difference
Take the arithmetic mean of the parallel determination results to report results. The absolute value of the difference between the results of parallel determination of not more than 0.0001%.
5.7 Determination of sulphate content
5.7.1 Principle of the method
The sample was evaporated to dryness, the residue was dissolved in hydrochloric acid, glycerol - ethanol mixture as stabilizer, barium chloride is added to obtain a suspension, with
Spectrophotometer suspension absorbance.
5.7.2 Reagents and solutions
5.7.2.1 dihydrate barium chloride (BaCl2 · 2H2O).
5.7.2.2 Glycerol - Ethanol mixture. 1 + 2.
5.7.2.3 hydrochloric acid solution. 1mol/L.
5.7.2.4 sulfate standard solution. 0.1g/L.
There are two preparation methods, choose one.
(1) Weigh 0.148g at (105 ~ 110) ℃ dried to a constant mass of anhydrous sodium sulfate, dissolved in water and transferred to 1000mL volumetric flask
And diluted to the mark.
(2) Weigh 0.181g at (105 ~ 110) ℃ dried to a constant mass of potassium sulfate, dissolved in water and transferred to 1000mL volumetric flask,
Dilute to the mark.
5.7.3 Instruments
General laboratory equipment and a spectrophotometer.
5.7.4 Analysis of step
5.7.4.1 Standard curve drawing
5.7.4.1.1 in Table 3 were weighed sulfate standard solution into seven 50mL volumetric flask.
Table 3
Sulfate standard solution/mL corresponding sulfates quality/mg
00
2.5 0.25
5.0 0.50
7.5 0.75
10.0 1.00
15.0 1.50
20.0 2.00
5.7.4.1.2 3mL hydrochloric acid solution were added to 5mL and glycerin to each flask - ethanol mixture, diluted with water to the mark,
Shake well.
5.7.4.1.3 solution into the flask containing 0.3g of barium chloride dihydrate dry beaker, two revolutions per second speed swing
2min. At room temperature, allowed to stand 10min.
5.7.4.1.4 with a suitable cuvette, at a wavelength of 450nm at zero spectrophotometer with the blank solution adjustment, assay solution absorbance.
5.7.4.1.5 sulphate content (mg) as abscissa and ordinate corresponding to the absorbance of the standard curve or calculate the linear regression equation.
5.7.4.2 Sample
Weigh about 20g sample (accurate to 0.01g), place the evaporating dish and evaporated to dryness on a steam bath, cooled to room temperature, the salt was added 3mL
Acid solution to dissolve the residue, all transferred to 50mL volumetric flask, add 5mL glycerol - ethanol mixture was diluted with water to the mark.
5.7.4.3 blank test
Without the sample, the sample was measured using the same analytical procedure, and the amount of reagent blank test.
5.7.4.4 Determination
5.7.4.4.1 The sample was carefully transferred containing 0.3g of barium chloride dihydrate dry beaker, two revolutions per second speed of shaking 2min. in
At room temperature, allowed to stand 10min.
5.7.4.4.2 with a suitable cuvette, at a wavelength of 450nm at the blank solution adjusting spectrophotometer zero absorbance assay solution.
5.7.5 Calculation Results
Sulfate content of sulfate (SO2-4) mass fraction 3 and its value is expressed in%, according to equation (3) Calculated.
-3
(3)
Where.
5.7.6 allowable difference
Take the arithmetic mean of the parallel determination results to report results. The absolute value of the difference between the results of parallel determination of not more than 0.001%.
5.8 Determination of free chlorine content
5.8.1 Principle of the method
Sample solution was added potassium iodide solution, precipitation iodine starch as indicator solution, titration with sodium thiosulfate standard solution titrate the liberated
iodine. Reaction is as follows.
2I- → -2e I2
I2 + 2S2O32 → - S4O2-6 + 2I-
5.8.2 Reagents and solutions
5.8.2.1 hydrochloric acid.
Oxide or reducing substance contained hydrochloric acid should be less than 0.0002%.
5.8.2.2 KI solution. 150g/L.
Weigh 15.0g of potassium iodide, dissolved in water and diluted with water to 100mL.
5.8.2.3 sodium thiosulfate standard titration solution. Ba (Na2S2O3) = 0.1mol/L.
5.8.2.4 Starch indicator solution. 10g/L.
The solution can only be retained for two weeks.
5.8.3 Instruments
And general laboratory equipment and the following instruments.
5.8.3.1 Erlenmeyer flask, 500mL (with ground glass stopper).
5.8.3.2 microburette.
5.8.4 Analysis of step
5.8.4.1 Sample
Weighed approximately 50mL sample and put the contents of about 100mL of water and has weighed (accurate to 0.01g) Erlenmeyer flask was cooled to room temperature, said
The amount of (accurate to 0.01g).
5.8.4.2 blank test
Without specimen, with an equal amount of hydrochloric acid in place of the sample, the sample was measured using the same analytical procedure, reagents and amount of Blank
test.
5.8.4.3 Determination
The test compound added 7mL potassium iodide solution, plugged cork shaken in the dark standing 2min. Add starch indicator solution 1mL with thiosulfate
Sodium standard solution titration solution titration to the blue disappeared as the end point.
5.8.5 Calculation Results
Free chlorine to the quality of chlorine (Cl) 4 scores count, values expressed in%, according to equation (4) calculations.
4 =
[(1- Vp V0)/1000] Ba M
100 =
(Vp 1- V0) Ba M
(4)
Where.
Accurate Ba --- sodium thiosulfate standard titration solution concentration value in units of moles per liter (mol/L);
Value V0 --- sodium thiosulfate standard titration solution consumed blank titration volume in milliliters (mL);
Numerical sodium thiosulfate standard titration Vp 1 --- sample titration solution consumed volume in milliliters (mL);
--- The M value chlorine (Cl) molar mass of the units of grams per mole (g/mol) (M = 35.45).
5.8.6 allowable difference
Take the arithmetic mean of the parallel determination results to report results. The absolute value of the difference between the results of parallel determination of not more than 0.001%.
5.9 Determination of reducing matter content
5.9.1 Principle of the method
In acidic medium, the single case of iodine starch indicator was blue, in case of reducing substances is reduced to elemental iodine solution color lighter or disappear.
5.9.2 Reagents and solutions
5.9.2.1 hydrochloric acid.
5.9.2.2 KI solution. 10g/L.
5.9.2.3 iodine standard solution. Ba 12I () 2 = 0.001mol/L;
Amount of 1mL iodine standard solution according to GB/T 601-2002 prepared, placed in 100mL volumetric flask, dilute to the mark. That
Solution was prepared prior to use.
5.9.2.4 Starch indicator solution. 10g/L.
5.9.3 Instruments
General laboratory equipment.
5.9.4 Determination
Amount of 1mL diluted hydrochloric acid (5.9.2.1), placed in 30mL test tube, with newly boiled and cooled water to 20mL, added
1mL potassium iodide solution, starch indicator solution 1mL and 2.0mL standard iodine solution, shake. 1mL sample was added to the tube, the solution
Blue does not disappear.
5.10 Determination of non-volatile matter content
5.10.1 Principle of the method
The amount of sample was evaporated to dryness, constant, weighing.
5.10.2 Instruments
General laboratory equipment.
5.10.3 analysis step
Weigh about 5g sample (accurate to 0.01g), moved already weighed (accurate to 0.0001g) evaporating dish, evaporated to dryness on a steam bath, and then
After drying at 110 ℃ 1h. Placed in a desiccator to cool to room temperature, weigh (accurate to 0.0001g).
5.10.4 Calculation Results
Non-volatile content mass fraction 5 and its value is expressed in%, according to equation (5) calculation.
100 (5)
Where.
5.10.5 allowable difference
Take the arithmetic mean of the parallel determination results to report results. The absolute value of the difference between the results of parallel determination of not more than 0.005%.
5.11 Determination of Arsenic
5.11.1 Determination of arsenic content diethyl dithiocarbamate silver spectrophotometry (Arbitration Act)
5.11.1.1 principle of the method
In an acidic medium with potassium iodide and stannous chloride As5 + reduced to As3 +, plus zinc particles react with acids to produce new ecological hydrogen to
As3 + further reduced to arsine was absorbed pyridine solution diethyl dithiocarbamate silver [Ag (DDTC)], generating purple colloid
Solution absorbance was measured with a spectrophotometer. Reaction is as follows.
AsH3 + 6Ag (DDTC) = 6Ag ↓ + 3H (DDTC) + As (DDTC) 3
5.11.1.2 Reagents and materials
The reagents used are not arsenic.
5.11.1.2.1 hydrochloric acid;
5.11.1.2.2 arsenic trioxide.
Arsenic trioxide is dangerous --- virulent.
5.11.1.2.3 zinc particles. particle size (0.5 ~ 1) mm.
5.11.1.2.4 potassium iodide solution. 150g/L;
Weigh 15.0g of potassium iodide, dissolved in water and diluted with water to 100mL.
5.11.1.2.5 stannous chloride hydrochloric acid solution. 400g/L;
Weigh 40.0g stannous chloride dihydrate (SnCl2 · 2H2O), was dissolved in 25mL of water and 75mL of hydrochloric acid mixed solution.
5.11.1.2.6 arsenic standard solution. 1mL solution of arsenic (As) 0.1mg;
Weigh 0.132g sulfuric acid and dried in a dryer to a constant mass of arsenic trioxide, warm dissolved in 1.2mL sodium hydroxide solution
(100g/L), transferred to 1000mL volumetric flask, dilute to the mark.
5.11.1.2.7 arsenic standard solution. 1mL solution of arsenic (As) 2.5mg;
Pipette Pipette 25mL said arsenic standard solution, placed in 1000mL volumetric flask, dilute to the mark, shake. The solution
Using now.
5.11.1.2.8 diethyl dithiocarbamate Silver pyridine solution. 5g/L;
Weigh 1.0g diethyl dithiocarbamate silver, dissolved in pyridine, was diluted to 200mL with pyridine. The solution was kept in a sealed brown
Color glass bottles. Valid for two weeks.
5.11.1.2.9 lead acetate cotton.
5.11.1.3 Instruments
All glassware should be carefully washed with hot concentrated sulfuric acid, and then rinsed with water and dried.
The following general laboratory equipment and instruments.
5.11.1.3.1 given arsenic (see Figure 1).
5.11.1.3.2 spectrophotometer.
5.11.1.4 analysis step
WARNING --- This test is part of the toxic agent, the test should be carried out in a fume hood.
5.11.1.4.1 standard curve drawing
Replace each batch of freshly prepared zinc particles or a diethyl dithiocarbamate silver pyridine solution should be re standard curve.
Millimeters
a --- 100mL flasks;
b --- connecting tube;
c --- 15 balls absorber.
Figure 1 a schematic view of a given arsenic
Table 4 5.11.1.4.1.1 amount of arsenic standard solution (5.11.1.2.7), six were placed in 100mL Erlenmeyer flasks (Figure 1).
Table 4
Arsenic standard solution/mL corresponds to arsenic mass/μg
0.0 0
1.0 2.5
2.0 5
4.0 10
6.0 15
8.0 20
5.11.1.4.1.2 10mL hydrochloric acid was added to each conical flask, add water to about 40mL.
5.11.1.4.1.3 weighed 5mL diethyl dithiocarbamate silver pyridine solution was placed in c of FIG. 1, and FIG. 1 c and discharge in advance
The Lead acetate cotton b connected.
After 5.11.1.4.1.4 sequentially added to each Erlenmeyer flask and a solution of potassium iodide 2mL 2mL stannous chloride hydrochloric acid solution, mix and let stand
15min. Plus 5g zinc tablets, according to diagram (see Figure 1) Connect the instrument quickly, the reaction 45min.
5.11.1.4.1.5 with a suitable cuvette, at a wavelength of 540nm Department to adjust the spectrophotometer blank solution zero absorption assay solution
Luminosity.
5.11.1.4.1.6 arsenic content (μg) as abscissa and the corresponding absorbance for the vertical axis of the standard curve or regression curve equation.
5.11.1.4.2 sample
Amount of 10.0mL sample weighed (accurate to 0.01g) (If the sample is too low arsenic content, can increase the sample size, and then heated to evaporate
About 10mL), moved to the Fig. 1a, add water to about 40mL.
5.11.1.4.3 blank test
Without the sample, add 10.0mL hydrochloric acid, add water to about 40mL, using the same sample and assay analysis step, and the amount of reagent
A blank test.
5.11.1.4.4 Determination
Conducted by 5.11.1.4.1.3 - 5.11.1.4.1.5 regulations.
5.11.1.5 Calculation Results
Arsenic content of arsenic (As) mass fraction 6 and its value is expressed in%, according to equation (6) Calculated.
-6
100 (6)
Where.
5.11.1.6 allowable difference
Take the arithmetic mean of the parallel determination results to report results. The absolute value of the difference between the results of parallel determination of not more than 0.00005%.
5.11.2 Determination of arsenic content Gutzeit method
5.11.2.1 principle of the method
In acidic solution, potassium iodide and stannous As5 + will be reduced to As3 +, plus zinc particles react with acids to produce new ecological hydrogen to
As3 + further reduced to arsine when arsine gas and mercury bromide paper effect, resulting in brownish yellow mercury arsenic with standard stain
Comparison.
5.11.2.2 Reagents and materials
The reagents used are not arsenic.
5.11.2.2.1 hydrochloric acid.
5.11.2.2.2 zinc particles. particle size (0.5 ~ 1) mm.
5.11.2.2.3 potassium iodide solution. 150g/L;
Weigh 15.0g of potassium iodide, dissolved in water and diluted with water to 100mL.
5.11.2.2.4 stannous chloride hydrochloric acid solution. 400g/L;
Weigh 40.0g stannous chloride dihydrate (SnCl2 · 2H2O), was dissolved in 25mL of water and 75mL hydrochloric acid (5.8.2.2.1) mixed solution
in. If the turbidity is heated to transparent.
5.11.2.2.5 arsenic standard solution. 1mL solution of arsenic (As) 1mg;
Pipette Pipette 10mL arsenic standard solution (5.11.1.2.6), placed 1000mL volumetric flask, dilute to the mark, shake.
The solution is using now.
5.11.2.2.6 lead acetate cotton.
5.11.2.2.7 mercuric bromide paper.
5.11.2.3 Instruments
General laboratory instruments and fixed arsenic (see Figure 2).
5.11.2.4 analysis step
5.11.2.4.1 sample
Weigh about 2g sample (accurate t...
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