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GB 5009.16-2014 PDF in English


GB 5009.16-2014 (GB5009.16-2014) PDF English
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GB 5009.16-2014: PDF in English

GB 5009.16-2014
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
National Food Safety Standard -
Determination of Tin in Food
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 
Method 1 - Hydride atomic fluorescence spectrometry ... 4 
2 Principle ... 4 
3 Reagents and materials ... 4 
4 Apparatus ... 5 
5 Analysis steps ... 6 
6 Expression of analysis results ... 7 
7 Precision ... 8 
8 Other ... 8 
Method Two - Phenyl ketone colorimetry ... 8 
9 Principle ... 8 
10 Reagents and materials ... 8 
11 Apparatus ... 10 
12 Analysis steps ... 10 
13 Expression of analysis results ... 11 
14 Precision ... 11 
15 Other ... 12 
National Food Safety Standard -
Determination of Tin in Food
1 Scope
This Standard specifies the determination methods of hydride atomic
fluorescence spectrometry and benzophenone colorimetry for tin in food.
This Standard is applicable to the determination of tin in canned solid food,
canned beverage, canned jam, canned infant formula and supplementary food.
Method 1 - Hydride atomic fluorescence spectrometry
2 Principle
After the sample is digested, a tin hydride (SnH4) is formed under the action of
sodium borohydride. And it is carried by the carrier gas into the atomizer for
atomization. The ground state tin atoms are excited to a high energy state under
the irradiation of a tin hollow cathode lamp. When it is deactivated back to the
ground state, fluorescence of characteristic wavelengths shall be emitted. Its
fluorescence intensity is proportional to the tin content. Perform quantitative
comparison with standard series solutions.
3 Reagents and materials
NOTE: Unless otherwise specified, the reagents used in this method are analytically pure, and the water
is the grade two water specified in GB/T 6682.
3.1 Reagents
3.1.1 Sulfuric acid (H2SO4): excellent grade pure.
3.1.2 Nitric acid (HNO3): excellent grade pure.
3.1.3 Perchloric acid (HClO4): excellent grade pure.
3.1.4 Thiourea (CH4N2S).
3.1.5 Ascorbic acid (C6H8O6).
4.2 Heating plate.
4.3 Electronic balance: resolutions are 0.1mg and 1mg.
5 Analysis steps
5.1 Sample preparation
For canned food, take the full amount of edible content to make into
homogenate or uniform powder.
5.2 Sample digestion
5.2.1 Weigh 1.0g~5.0g of sample into a conical flask. Add 20.0mL of nitric acid-
perchloric acid mixed solution (4+1). Add 1.0mL of sulfuric acid and 3 glass
beads. Place overnight. Heat and digest on heating plate next day. If the acid
solution is too small, appropriately add nitric acid. Continue digesting to white
smoke. Remove for cooling when the liquid volume is nearly 1mL. Use water to
transfer the digested sample into a 50mL volumetric flask. Add water to set
volume to the scale. Shake well for use. Carry out the blank test at the same
time (If the tin content in the sample solution is outside the range of the standard
curve, use water to dilute; add sulfuric acid to make the final sulfuric acid
concentration equal to the standard series solution).
5.2.2 Take 10.0mL of sample in 5.2.1 that the volume has been set into a 25mL
colorimetric tube. Add 3.0mL of sulfuric acid solution (1+9). Add 2.0mL of
thiourea (150 g/L) + ascorbic acid (150 g/L) mixed solution. Then use water to
set volume to 25mL. Shake well.
5.3 Instrument reference conditions
Reference conditions for atomic fluorescence spectrometer analysis:
- Negative high pressure: 380V;
- Light current: 70mA;
- Atomization temperature: 850°C;
- Furnace height: 10mm;
- Shielding gas flow: 1200 mL/min;
- Carrier gas flow rate: 500 mL/min;
- Measurement method: standard curve method;
V3 - set volume of solution for determination, in milliliters (mL);
m - sample mass, in grams (g);
V2 - volume of sample digestive solution taken for determination, in milliliters
(mL);
1000 - conversion factor.
Two digits after the decimal point are reserved when the calculation result is
less than 10 mg/kg. Two significant digits are retained when the calculation
result is greater than 10 mg/kg.
7 Precision
The absolute difference between two independent determinations obtained
under repeatability conditions shall not exceed 10% of the arithmetic mean.
8 Other
When the sampling amount is 1.0g, the limit of quantification of the method is
2.5 mg/kg.
Method Two - Phenyl ketone colorimetry
9 Principle
After the sample is digested, the tetravalent tin ion forms a sparingly soluble
orange-red complex with benzophenone in a weakly acidic solution. Perform
quantitative comparison with standard series solutions in the presence of
protective colloids.
10 Reagents and materials
NOTE: Unless otherwise specified, the reagents used in this method are analytically pure, and the water
is the grade three water specified in GB/T 6682.
10.1 Reagents
10.1.1 Tartaric acid (C4H4O6H2).
Cover with watch glass. Heat till tin is completely dissolved. Remove water
glass. Continue heating till thick white smoke appears. Cool. Slowly add 50mL
of water. Transfer into a 100mL volumetric flask. Use sulfuric acid solution (1+9)
to rinse the beaker several times. Merge the washing liquid into the volumetric
flask. Dilute to the scale. Mix well.
10.4.2 Tin standard use solution: Pipette 10.0mL of tin standard solution. Place
into a 100mL volumetric flask. Use sulfuric acid solution (1+9) to dilute to the
scale. Mix well. Dilute in this way again till it is equivalent to 10.0μg tin per
millimeter.
11 Apparatus
11.1 Spectrophotometer.
11.2 Electronic balance: resolutions are 0.1mg and 1mg.
12 Analysis steps
12.1 Sample preparation
12.1.1 Sample digestion is same as 5.2.1.
12.1.2 Pipette 1.00mL~5.00mL of sample digestive solution and the same
amount of reagent blank solution. Respectively place in 25mL colorimetric tubes.
Separately add 0.5mL of tartaric acid solution (100 g/L) and 1 drop of
phenolphthalein indicator solution (100 g/L) into sample digestive solution and
reagent blank solution. Mix well. Respectively add ammonia solution (1+1) to
neutralize till light red. Add 3.0mL of sulfuric acid solution (1+1), 1.0mL of animal
glue solution (5.0 g/L) and 2.5mL of ascorbic acid solution (10.0 g/L). Then add
water to 25mL. Mix well. Then respectively add 2.0mL of benzophenone
solution (0.1 g/L). Mix well. Measure after placing for 1h.
12.2 Production of standard curve
Pipette 0.00mL, 0.20mL, 0.40mL, 0.60mL, 0.80mL, 1.00mL of tin standard
solutions (equivalent to 0.00μg, 2.00μg, 4.00μg, 6.00μg, 8.00μg, 10.00μg of tin).
Respectively place them into 25mL colorimetric tubes. Add 0.5mL of tartaric
acid solution (100 g/L) and 1 drop of phenolphthalein indicator solution (10.0
g/L) respectively. Mix well. Respectively add ammonia solution (1+1) to
neutralize till light red. Add 3.0mL of sulfuric acid solution (1+9), 1.0mL of animal
glue solution (5.0 g/L) and 2.5mL of ascorbic acid solution (10.0 g/L). Then add
water to 25mL. Mix well. Add 2.0mL of benzophenone solution respectively. Mix
well. Measure after placing for 1h.
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.