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National food safety standard - Determination of chromium in foods
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Standard ID | GB 5009.123-2023 (GB5009.123-2023) | Description (Translated English) | (National food safety standards Determination of fructose, glucose, sucrose, maltose and lactose in food) | Sector / Industry | National Standard | Classification of Chinese Standard | X09 | Word Count Estimation | 19,152 | Date of Issue | 2023-09-06 | Date of Implementation | 2024-03-06 | Issuing agency(ies) | National Health Commission of the People's Republic of China, State Administration for Market Regulation | Summary | This standard specifies the methods for the determination of fructose, glucose, sucrose, maltose and lactose in foods. The first method of high performance liquid chromatography is suitable for the determination of fructose, glucose, sucrose, maltose, and lactose in grains and grain products, milk and dairy products, fruits, vegetables, and fruit and vegetable products, sweeteners, candies, beverages, and infant foods. The second method, ion chromatography, is suitable for the determination of fructose, glucose, sucrose, maltose, and lactose in food. The third method is the acid hydrolysis-Rhein-Eynon method, which is suitable for the determination of sucrose in food. The fourth method, the Rhein-Eynon method, is suitable for the determination of lactose in infant foods and dairy products. | Standard ID | GB 5009.123-2014 (GB5009.123-2014) | Description (Translated English) | National Food Safety Standard- Determination of chromium in foods | Sector / Industry | National Standard | Classification of Chinese Standard | C53 | Classification of International Standard | 67.040 | Word Count Estimation | 7,794 | Date of Issue | 2015/1/28 | Date of Implementation | 2015/7/28 | Older Standard (superseded by this standard) | GB/T 5009.123-2003 | Administrative Organization | National Health and Family Planning | Regulation (derived from) | National Health and Family Planning Committee Announcement 2015 No. 2 | Issuing agency(ies) | National Health and Family Planning Commission of the People's Republic of China | Summary | This Standard specifies the chromium in food by graphite furnace atomic absorption spectrometric method. This Standard applies to the determination of chromium content in various foods. | Standard ID | GB/T 5009.123-2003 (GB/T5009.123-2003) | Description (Translated English) | Determination of chromium in foods | Sector / Industry | National Standard (Recommended) | Classification of Chinese Standard | C53 | Classification of International Standard | 67.040 | Word Count Estimation | 6,676 | Date of Issue | 2003-08-11 | Date of Implementation | 2004-01-01 | Older Standard (superseded by this standard) | GB/T 14962-1994 | Drafting Organization | Health and Epidemic Prevention Station of Hebei Province | Administrative Organization | People's Republic of China Ministry of Health | Proposing organization | Ministry of Health of the People Republic of China | Issuing agency(ies) | The People Republic of China Ministry of Health, China National Standardization Management Committee | Summary | This standard specifies: Determination of total chromium in foods and graphite furnace atomic absorption polarography content. This standard applies to: all kinds of food in the total chromium determination. The standard detection limit |
GB 5009.123-2023
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
National Food Safety Standard - Determination of
Chromium in Foods
ISSUED ON: SEPTEMBER 6, 2023
IMPLEMENTED ON: MARCH 6, 2024
Issued by: National Health Commission of the People’s Republic of China;
State Administration for Market Regulation.
Table of Contents
Foreword ... 3
1 Scope ... 4
Method I - Graphite Furnace Atomic Absorption Spectrometry ... 4
2 Principle ... 4
3 Reagents and Materials ... 4
4 Instruments and Equipment ... 5
5 Analytical Procedures ... 6
6 Expression of Analysis Results ... 8
7 Precision ... 9
8 Others ... 9
Method II - Inductively Coupled Plasma Mass Spectrometry ... 9
Appendix A Microwave Digestion Temperature Rise Program and Instrument
Reference Conditions of Graphite Furnace Atomic Absorption Spectrometry ... 10
National Food Safety Standard - Determination of
Chromium in Foods
1 Scope
This Standard specifies the method for the determination of chromium in foods by graphite
furnace atomic absorption spectrometry and inductively coupled plasma mass spectrometry.
This Standard is applicable to the determination of chromium in foods.
Method I - Graphite Furnace Atomic Absorption
Spectrometry
2 Principle
After the specimen is digested, atomize it in a graphite furnace, at 357.9 nm, determine the
absorbance. Within a certain concentration range, the absorbance value of chromium is
proportional to the chromium content. Conduct quantitative comparison with standard series
solutions.
3 Reagents and Materials
Unless it is otherwise specified, the reagents used in this Method are all excellent-grade pure,
and the water is Grade-2 water specified in GB/T 6682.
3.1 Reagents
3.1.1 Nitric acid (HNO3).
3.1.2 Perchloric acid (HClO4).
3.1.3 Ammonium dihydrogen phosphate (NH4H2PO4).
3.2 Preparation of Reagents
3.2.1 Nitric acid solution (5 + 95): measure-take 50 mL of nitric acid, slowly add it to 950 mL
of water and evenly mix it.
3.2.2 Nitric acid solution (1 + 1): measure-take 50 mL of nitric acid, slowly add it to 50 mL of
water and evenly mix it.
3.2.3 Ammonium dihydrogen phosphate solution (20 g/L): weigh-take 2 g of ammonium
dihydrogen phosphate, add a small amount of nitric acid solution (5 + 95) to dissolve it, then,
use nitric acid solution (5 + 95) to reach a constant volume of 100 mL, and evenly mix it.
3.3 Reference Material
Potassium dichromate (K2Cr2O7, CAS No.: 7778-50-9): purity > 99.99%, or a standard
substance certified by the state and awarded a reference material certificate.
3.4 Preparation of Standard Solutions
3.4.1 Chromium standard stock solution (1,000 mg/L): accurately weigh-take 0.2829 g of
potassium dichromate (110 C, bake for 2 h), dissolve it in water, then, transfer into a 100 mL
volumetric flask. Use nitric acid solution (5 + 95) to dilute it to the scale and evenly mix it. The
mass concentration of chromium in this solution is 1,000 mg/L.
3.4.2 Chromium standard intermediate solution (1,000 g/L): accurately draw 1.00 mL of
chromium standard stock solution (1,000 mg/L) into a 10 mL volumetric flask, add nitric acid
solution (5 + 95) to the scale, and evenly mix it. Then, accurately draw 1.00 mL of the above-
mentioned solution into a 100 mL volumetric flask, add nitric acid solution (5 + 95) to the scale,
and evenly mix it. The mass concentration of chromium in this solution is 1,000 g/L.
3.4.3 Chromium standard series of solutions: respectively and accurately draw 0 mL, 0.150 mL,
0.400 mL, 0.800 mL, 1.20 mL and 1.60 mL of chromium standard intermediate solution into a
100 mL volumetric flask. Add nitric acid solution (5 + 95) to the scale, and evenly mix it. The
mass concentration of chromium in this series of solutions is 0 g/L, 1.50 g/L, 4.00 g/L, 8.00
g/L, 12.0 g/L and 16.0 g/L. Prepare them right before use.
NOTE: the mass concentration of chromium in the standard series of solutions can be determined
in accordance with the sensitivity of the instrument and the actual chromium content in the
sample.
4 Instruments and Equipment
NOTE: all glassware and polytetrafluoroethylene digestion inner tanks need to be soaked in nitric
acid solution (1 + 5) overnight, repeatedly rinsed with tap water, and finally, thoroughly
rinsed with water.
4.1 Atomic absorption spectrometer: equipped with graphite furnace atomizer and chromium
hollow cathode lamp.
4.2 Electronic balance: with a division value of 0.1 mg and 1 mg.
4.3 Adjustable electric heating plate or adjustable electric stove.
4.4 Microwave digestion system: equipped with polytetrafluoroethylene digestion inner tank.
digestion tube with scale. For samples containing ethanol or carbon dioxide, firstly heat them
at a low temperature to remove ethanol or carbon dioxide, add 10 mL of nitric acid and 0.5 mL
of perchloric acid, and digest on an adjustable electric furnace (reference conditions: at 120 C,
maintain for 0.5 h ~ 1 h, raise to 180 C, maintain for 2 h ~ 4 h, raise to 200 C ~ 220 C). If
the digestion solution is brown, after cooling, add a small amount of nitric acid and digest it,
until it emits white smoke, and the digestion solution turns colorless, transparent or slightly
yellow. Drive acid to about 0.5 mL, take out the digestion tube, cool it and use water to reach a
constant volume of 10 mL or 25 mL, evenly mix it and reserve it for later use. Meanwhile,
conduct a blank test. Alternatively, a conical flask can also be used; on an adjustable electric
heating plate, in accordance with the above-mentioned operation method, perform wet digestion.
5.2.1.2 Microwave digestion method
For solid specimens, weigh-take 0.2 g ~ 0.5 g (accurate to 0.001 g; for samples containing
relatively high-water content, the sampling size can be appropriately increased to 1 g). For
liquid specimens, accurately transfer-take or weigh-take 0.500 mL (g) ~ 3.00 mL (g) (accurate
to 0.001 g) into a microwave digestion tank. For samples containing ethanol or carbon dioxide,
firstly heat them at a low temperature to remove ethanol or carbon dioxide, add 5 mL ~ 10 mL
of nitric acid, in accordance with the operation procedures of microwave digestion, digest the
specimen. For the digestion conditions, refer to Table A.1 in Appendix A. When necessary, after
adding acid, cover and let it stand for 1 h or overnight, then, in accordance with the operation
procedures of microwave digestion, digest the specimen. After cooling, take out the digestion
tank; at 140 C ~ 160 C, drive acid to about 1 mL. After the digestion tank cools, transfer the
digestion solution into a 10 mL of 25 mL volumetric flask. Use a small amount of water to wash
the digestion tank 2 ~ 3 times, combine the washing liquid in the volumetric flask and use water
to reach a constant volume to the scale; evenly mix it and reserve it for later use. Meanwhile,
conduct a blank test.
5.2.1.3 Pressure tank digestion method
For solid specimens, weigh-take 0.2 g ~ 1 g (accurate to 0.001 g; for samples containing
relatively high-water content, the sampling size can be appropriately increased to 2 g). For
liquid specimens, accurately transfer-take or weigh-take 0.500 mL (g) ~ 5.00 mL (g) (accurate
to 0.001 g) into a digestion inner tank. For samples containing ethanol or carbon dioxide, firstly
heat them at a low temperature to remove ethanol or carbon dioxide and add 5 mL ~ 10 mL of
nitric acid. Properly put on the inner cover, tighten the stainless-steel jacket, put it into a
constant-temperature drying oven; at 140 C ~ 160 C, maintain for 4 h ~ 5 h. When necessary,
after adding acid, cover and let it stand for 1 h or overnight, then, tighten the stainless-steel
jacket and put it into a constant-temperature drying oven to digest the specimen. After cooling,
slowly unscrew the stainless-steel jacket, take out the digestion inner tank; at 140 C ~ 160 C,
drive acid to about 1 mL. After cooling, transfer the digestion solution to a 10 mL or 25 mL
volumetric flask, use a small amount of water to wash the inner tank and inner cover for 2 ~ 3
times, combine the washing liquid in the volumetric flask and use water to reach a constant
volume to the scale; evenly mix it and reserve it for later use. Meanwhile, conduct a blank test.
5.2.1.4 Dry digestion method
X---the chromium content in the specimen, expressed in (mg/kg) or (mg/L);
ρ---the mass concentration of chromium in the specimen digestion solution, expressed in (g/L);
ρ0---the mass concentration of chromium in the blank solution, expressed in (g/L);
f---dilution factor;
V---the constant volume of the specimen digestion solution, expressed in (mL);
m---the mass or volume of the specimen, expressed in (g) or (mL);
1,000---conversion factor.
When the chromium content is 1 mg/kg (mg/L), the calculation results shall retain 3
significant figures. When the chromium content is < 1 mg/kg (mg/L), the calculation results
shall retain 2 significant figures.
7 Precision
When the chromium content in the specimen is > 1 mg/kg (mg/L), the absolute difference
between the results of two independent determinations obtained under repeatability conditions
shall not exceed 10% of the arithmetic mean. When 0.1 mg/kg (mg/L) < chromium content in
the specimen 1 mg/kg (mg/L), the absolute difference between the results of two independent
determinations obtained under repeatability conditions shall not exceed 15% of the arithmetic
mean. When the chromium content in the specimen is 0.1 mg/kg (mg/L), the absolute
difference between the results of two independent determinations obtained under repeatability
conditions shall not exceed 20% of the arithmetic mean.
8 Others
When the sampling size is 0.5 g or 2 mL and the constant volume is 10 mL, the detection limit
of this Method is 0.01 mg/kg or 0.003 mg/L, and the quantitation limit is 0.03 mg/kg or 0.008
mg/L.
Method II - Inductively Coupled Plasma Mass Spectrometry
See Method I of GB 5009.268.
......
GB 5009.123-2014
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
National Food Safety Standard - Determination of
chromium in foods
ISSUED ON: JANUARY 28, 2015
IMPLEMENTED ON: JULY 28, 2015
Issued by: National Health and Family Planning Commission of the
People’s Republic of China.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Principle ... 4
3 Reagents and materials ... 4
4 Instruments and apparatuses ... 5
5 Analysis steps ... 6
6 Description of the analysis result ... 7
7 Precision ... 8
8 Others ... 8
Appendix A Reference conditions of sample determination ... 9
National Food Safety Standard - Determination of
chromium in foods
1 Scope
This Standard specifies the graphite furnace atomic absorption spectrometry
method for the determination of chromium in foods.
This Standard applies to the determination of chromium in various foods.
2 Principle
After the sample is digested, use the graphite furnace atomic absorption
spectrometry to measure the absorption value at 357.9 nm; compare the
absorption value with the standard series solution within a certain concentration
range.
3 Reagents and materials
Note: Unless otherwise specified, the reagents which are used in this method
are all guaranteed reagents; the water is grade-II water that is specified
in GB/T 6682.
3.1 Reagents
3.1.1 Nitric acid (HNO3).
3.1.2 Perchloric acid (HClO4).
3.1.3 Ammonium dihydrogen phosphate (NH4H2PO4).
3.2 Preparation of reagents
3.2.1 Nitric acid solution (5+95): Measure 50 mL of nitric acid and slowly pour it
into 950 mL of water; mix well.
3.2.2 Nitric acid solution (1+1): Measure 250 mL of nitric acid and slowly pour it
into 250 mL of water; mix well.
3.2.3 Ammonium dihydrogen phosphate solution (20 g/L): Weigh 2.0 g of
ammonium dihydrogen phosphate; dissolve in water; dilute to 100 mL; mix well.
5 Analysis steps
5.1 Pretreatment of the sample
5.1.1 For grains, beans, after removing the impurities, crush them and put them
into clean containers as samples. Seal and mark; the samples shall be stored
at room temperature.
5.1.2 For fresh samples of high moisture content, such as vegetables, fruits,
fish, meat and eggs, directly stir them into homogenate and put them into clean
containers as samples. Seal and mark. The samples shall be kept in the
refrigerator freezer.
5.2 Sample digestion
5.2.1 Microwave digestion
Accurately weigh 0.2 g ~ 0.6 g (accurate to 0.001 g) of the sample in the
microwave digestion tank; add 5 mL of nitric acid; digest the sample according
to the microwave digestion steps (see A.1 for digestion conditions). After cooling,
take out the digestion tank; reduce the acid to 0.5 mL ~ 1.0 mL at 140 °C ~
160 °C on the electric heating plate. After the digestion tank is left cold, transfer
the digestion solution to a 10 mL volumetric flask; use a small amount of water
to wash the digestion tank 2 ~ 3 times; combine the washing solution; use water
to dilute to the mark. Do a reagent blank test at the same time.
5.2.2 Wet digestion
Accurately weigh 0.5 g ~ 3 g of the sample (accurate to 0.001 g) into the
digestion tube; add 10 mL of nitric acid, 0.5 mL of perchloric acid; digest on an
adjustable electric furnace (reference conditions: keep at 120 °C for 0.5 h ~ 1
h; heat up to 180 °C for 2 h ~ 4 h; heat up to 200 °C ~ 220 °C). If the digestive
juice is brown, add more nitric acid to dissolve until white smoke appears; when
the digestive juice is colorless, transparent or slightly yellow, take out the
digestive tube and use water to dilute to 10 mL after cooling. Do a reagent blank
test at the same time.
5.2.3 High pressure digestion
Accurately weigh 0.3 g ~ 1 g of sample (accurate to 0.001 g) into the digestion
inner tank; add 5 mL of nitric acid. Close the inner cover; screw the stainless-
steel jacket tightly; put it in a constant-temperature drying oven; keep it at
140 °C ~ 160 °C for 4 h ~ 5 h. Naturally cool in the box to room temperature;
slowly unscrew the outer tank; take out the digestion inner tank; place it on the
adjustable electric heating plate at 140 °C ~ 160 °C to reduce the acid to 0.5
mL ~ 1.0 mL. After cooling, transfer the digestion solution to a 10 mL volumetric
Where:
X -- content of chromium in the sample, in milligrams per kilogram (mg/kg);
c -- content of chromium in the working sample solution, in nanograms per
milliliter (ng/mL);
c0 -- content of chromium in the blank solution, in nanograms per milliliter
(ng/mL);
V -- total volume of the sample digestion solution at a constant volume, in
milliliters (mL);
m -- sample weighing amount, in grams (g);
1 000 -- conversion coefficient.
When the analysis result is ≥1 mg/kg, retain three significant digits; when the
analysis result is <1 mg/kg, retain two significant digits.
7 Precision
The absolute difference of two independent test results under repeatability
cannot exceed 20% of the arithmetic mean value.
8 Others
Calculate by the weighing amount of 0.5 g and the constant volume of 10 mL;
the detection-limit of the method is 0.01 mg/kg; the quantitation-limit is 0.03
mg/kg.
......
GB/T 5009.123-2003
GB/T5009.123-2003
GB
ICS 67.040
C 53
NATIONAL STANDARD
OF THE PEOPLE’S REPUBLIC OF CHINA
Replacing GB/T 14962-1994
Determination of chromium in foods
ISSUED ON. AUGUST 11, 2003
IMPLEMENTED ON. JANUARY 01, 2004
Issued by.
Ministry of Health of the People’s Republic of China;
Standardization Administration of the People’s Republic of
China.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Principle ... 4
3 Reagents ... 4
4 Instruments ... 4
5 Analysis Procedures ... 5
6 Result calculation ... 6
7 Precision ... 6
8 Principle ... 7
9 Reagents ... 7
10 Instruments ... 8
11 Analysis procedure ... 8
12 Result calculation ... 9
13 Precision ... 9
Foreword
This Standard replaces GB/T 14962-1994 Method for determination of chromium in foods.
Compared with GB/T 14962-1994, main changes of this Standard are as follows.
— Change the Chinese name of standard to Determination of chromium in foods;
— Revise the structure of previous standard according to GB/T 20001.4-2001 Rules
for drafting standards - Part 4. Methods of chemical analysis.
This Standard was proposed by and shall be under the jurisdiction of Ministry of Health of
the People’s Republic of China.
The responsible drafting organizations of method I of this Standard. Hebei Sanitation and
Anti-epidemic Station, Henan Food Hygiene Supervision and Inspection Institute, West
China Medical University, and Nanjing Railway Medical College.
The responsible drafting organizations of method II of this Standard. West China Medical
University and Institute of Nutrition and Food Hygiene, and Chinese Academy of
Preventive Medicine.
The chief drafting staffs of method I of this Standard. Zhang Xinmian, Wang Huaizhou, Li
Fasheng, Tian Yongbi, and Jiang Zhaokun.
The chief drafting staffs of method II of this Standard. Wang Guangjian, Tian Yongbi, and
Wang Huaizhou.
Previous standard was issued in 1994. This version is the first revision.
Determination of chromium in foods
1 Scope
This Standard specifies the content of chromium in foods which is determined by graphite
furnace atomic absorption spectrometry (GFAAS) and oscilloscope polarography method.
This Standard is applicable to the determination of total chromium in all kinds of foods.
Detection limit of this Standard. GFAAS is 0.2ng/mL; oscilloscope polarography method is
1ng/mL.
First method Graphite Furnace Atomic Absorption Spectrometry (GFAAS)
2 Principle
After digestion, the sample is dissolved by deionized water and diluted to certain volume.
Absorb appropriate amount of liquid sample into graphite furnace atomizer to atomize.
Under the parameters of selected instrument, chromium absorbs the resonance line with
wavelength of 357.9nm; the absorbance is in proportion to content of chromium.
3 Reagents
3.1 Nitrate.
3.2 Perchloric acid.
3.3 Hydrogen peroxide.
3.4 1.0mol/L nitrate solution.
3.5 Chromium standard solution. Dissolve 1.4135g of guaranteed reagent dichromate
(baked at 110 °C for 2 h) in water. Dilute with water to 500mL. This solution contains
1.0mg/mL chromium and is the standard stock solution. When using, dilute it with 1.0mol/L
nitrate into standard solution with 100ng/mL chromium.
4 Instruments
Soak the glassware and teflon inner-barrel of high-pressure digestion tank in hot
hydrochloric acid (1+1) for 1h. Use hot nitrate (1+1) to soak for 1h. Then use water to rinse
thoroughly before each use.
4.1 Atomic absorption spectrophotometer
refrigerator for long-term storage.
9.7.2 1×10-3 mol/L α,α’-bipyridine solution.
Absorb 10.0mL of 1×10-2 mol/L α,α’-bipyridine solution. Add water to dilute to 100mL. Mix
well.
9.8 6 mol/L sodium nitrite solution.
Weigh 41.4g of sodium nitrite (AR) to dissolve in water. Add water to dilute to 100mL. Mix
well. Store in refrigerator.
10 Instruments
10.1 Oscillographic polarograph.
10.2 Voltage-regulated and temperature-control electric hot plate.
11 Analysis procedure
11.1 Accurately weigh 1g~2g of representative sample into a 150mL conical flask. Add
3.0mL of sulfuric acid and 20mL~30mL of hydrogen peroxide. Place on the electric hot
plate. Heat and digest them at 160°C~200°C until they are in colorless and transparent
solution (if necessary, it may add hydrogen peroxide). Continue to heat until hydrogen
peroxide is completely decomposed and sulfur trioxide (SO3) smoke appears in flask.
Take down to cool. Add 10mL of water and 2 drops of thymol blue indicator. Neutralize it
with 1mol/L sodium hydroxide until the solution just turns to blue. Additionally add 20
drops. Add 2mL of hydrogen peroxide. Heat to dissolve on hot plate at 160°C~200°C.
After most of hydrogen peroxide is decomposed, add 10 drops of 0.5% potassium iodide
solution. Continue to heat until hydrogen peroxide is completely decomposed. Take down
to cool. Use water to transfer into a 50mL volumetric flask. Dilute to scale. Take 5.0 mL of
this solution and place into a 25mL colorimetric tube for analysis. Meanwhile, make
digestion blank.
11.2 Standard curve
Respectively add 0.00, 0.20, 0.50, 1.00, 2.00, 3.00 and 4.00 mL of standard application
solution (equivalent to 0.00, 0.02, 0.05, 0.10, 0.20, 0.30 and 0.40 µgCr) into 25mL
colorimetric tubes. Respectively add 1.0mL of 5.4mol/L sulfuric acid, 1 drop of thymol blue
indicator. Neutralize them with 10 mol/L sodium hydroxide until the solution just turns to
blue. Additionally add 2 drops. Mix well.
11.3 Determination
In sample and standard series tubes, respectively add 2.5mL of ammonia-ammonium
chloride buffer solution, 1.0mL of 1×10-3 mol/L α,α’-bipyridine solution, and 1.0mL of 6
mol/L sodium nitrite solution. Dilute to 25mL. Mix well. On oscillographic polarograph, use
three-electrode, cathodic, original potential -1.2V to read the peak height of second
derivative peak of chromium polarographic peak.
12 Result calculation
The result shall be calculated according to Formula (2).
Where.
X — The content of chromium in sample. Unit is [mg/kg(mg/L)];
A — The content of chromium in sample digestive liquid. Unit is µg;
V1 — The total volume of sample digestive liquid. Unit is mL;
V — The volume of sample digestive liquid for determination. Unit is mL;
m — The mass or volume of sample. Unit is [g(mL)].
13 Precision
Under the repeatability condition, the absolute difference of two independent determined
results shall not be over 15% of arithmetic mean.
......
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