SN/T 1004-2013 English PDF (SNT1004-2013)

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SN/T 1004-2013: Determination of urea residues in canned foods for export
SN/T 1004-2013
GB
INDUSTRY STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
Replacing SN/T 1004-2001
Determination of urea residues in canned foods for export
ISSUED ON. AUGUST 30, 2013
IMPLEMENTED ON. MARCH 01, 2014
Issued by. General Administration of Quality Supervision, Inspection and
Quarantine of the People's Republic of China
Table of Contents
The first method - Liquid chromatography ... 4 
1 Scope ... 4 
2 Method abstract ... 4 
3 Reagents and materials ... 4 
4 Instruments and equipment ... 5 
5 Sample preparing and preserving ... 5 
6 Determining procedure ... 5 
7 Result calculation and expression ... 7 
8 Quantitative limit, recovery rate ... 7 
The second method - Spectrophotography ... 9 
9 Scope ... 9 
10 Method abstract ... 9 
11 Reagents ... 9 
12 Instruments ... 10 
13 Analysing procedure ... 10 
14 Result calculation and expression ... 11 
15 Quantitative limit, recovery rate ... 11 
Foreword
This Standard is drafted in accordance with specifications of GB/T 1.1-2009.
This Standard replaces SN/T 1004-2001 "Method for the determination of urea residues in
canned mushroom for export".
Compared with SN/T 1004-2001, the main technical changes, besides editorial
amendments, are as follows.
-- The standard tile is amended as "Determination of urea residues in canned foods
for export";
-- The applicable scope is extended to. canned edible fungus, fruits, vegetables,
fishes and meats;
-- Liquid chromatography is added as the first method;
-- Spectrophotography is amended as the second method, and test conditions are
improved;
-- Content of sampling is deleted.
Please note that this document may involve patents. The issuing agency of this Standard
is not responsible for identification of these patents.
This Standard was proposed by and shall be under the jurisdiction of Certification and
Accreditation Administration of the People’s Republic of China.
The main drafting organizations of this Standard. Inspection and Quarantine Technical
Centre of Xiamen Entry-Exit Inspection and Quarantine Bureau of the People’s Republic
of China, and Yunnan Entry-Exit Inspection and Quarantine Bureau of the People’s
Republic of China.
The main drafters of this Standard. Xu Dunming, Zhang Jin, Wang Yigeng, Li Zhihuang,
Peng Yunxia, Chen Dajie and Zhou Xian.
The previous edition replaced by this Standard is as follows.
-- SN/T 1004-2001.
Determination of urea residues in canned foods for export
The first method - Liquid chromatography
1 Scope
This Standard specifies the high performance liquid chromatography for determination of
urea residues in canned foods for export.
This Standard is applicable to determination of urea residues in canned edible fungus,
fruits, vegetables, fishes and meats.
2 Method abstract
The sample is extracted with 1% acetic acid solution; use xanthydrol to
fluorescent-derivatize; use liquid chromatography - fluorescent detector to determine; use
external standard method to quantity.
3 Reagents and materials
Unless otherwise specified, all reagents are analytical reagents; water is deionized water.
3.1 Methanol. chromatographically pure.
3.2 Trichloromethane. chromatographically pure.
3.3 Acetic acid. chromatographically pure.
3.4 Hydrochloric acid.
3.5 Octane sulfonic natrium.
3.6 Xanthydrol (Xanthydrol, CAS code 90-46-0). purity is higher than 99%.
3.7 1% acetic acid solution. get 10mL of acetic acid; put it in 1000mL volumetric flask; use
water to dilute it to 1000mL.
3.8 1% hydrochloric acid solution. get 10mL of hydrochloric acid; put it in 1000mL
volumetric flask. Use water to dilute it to 1000mL.
3.9 20mmol/L octane sulfonic natrium solution. weigh precisely 20mmol(4.32g) of octane
sulfonic natrium; dissolve it into 1000mL water. Use phosphoric acid to adjust the pH
value to 4.0.
3.10 Xanthydrol derivatizing reagent. weigh precisely 0.1g of xanthydrol; put it in 1000mL
volumetric flask. Dissolve it with methanol to make the solution volume to be 100mL.
3.11 Urea’s reference material (Urea, CAS code 96-45-7). purity is higher than 99%.
3.12 Standard stock solution. weigh precisely 100.0mg of urea’s reference material. Dilute
with water to 100mL to get 1g/L standard stock solution.
3.13 Standard working solution. prepare it when using. Standard stock solution is diluted
with water step-by-step until the required concentration is reached.
3.14 Millipore filter. 0.22μm, organic phase type.
4 Instruments and equipment
4.1 High performance liquid chromatograph. equipped with fluorescence detector.
4.2 Tissue blender.
4.3 Homogenizer.
4.4 Turbine mixer.
4.5 Centrifuge.
4.6 Analytical balances. sensibility is 0.1mg and 0.01g respectively.
4.7 Volumetric flasks. 50mL, 100mL, 1000mL.
4.8 Pipets. 10~100μL and 100~1000μL.
4.9 Polypropylene centrifugal tubes. 50mL and 15mL with plug.
5 Sample preparing and preserving
5.1 Requirements
During the preparation of sample, pollution of sample and residue content change shall be
prevented.
5.2 Sample preparing
Get 500g of representative sample. Use blender to blend it; mix it uniformly. Divide the
sample into two portions; put them in clean containers. Then seal the containers; mark
them clearly.
5.3 Sample preserving
Preserve the sample at -18°C.
6 Determining procedure
6.1 Extracting
Weigh 5.0g (accurate to 0.1g) of sample; put it into a 50mL centrifuge tube with plug. Add
The second method - Spectrophotography
9 Scope
This Standard specifies the spectrophotography for determination of urea residues in
canned foods for export.
This Standard is applicable to determination of urea residues in canned edible fungus,
fruits, vegetables, fishes and meats.
10 Method abstract
Use protein precipitant to remove protein in sample; decolorize it with activated carbon.
Analysis target condensate and diacetyl monoxime, in acidic condition, produce
condensation through catalysis; and produce 4,5 dimethyl-2-iminazole compound in
existence of thiosemicarbazide. The absorbance at 525nm is in proportion to urea content.
Determine with spectrophotography; quantify with external standard method.
11 Reagents
Unless otherwise specified, all reagents are analytical reagents, and water is deionized.
11.1 Glacial acetic acid.
11.2 Concentrated sulfuric acid.
11.3 Phosphoric acid. 85%.
11.4 Zinc acetate [Zn(CHCOO)·2H2O].
11.5 Potassium ferrocyanide [K4Fe(CN)6·3H2O].
11.6 Thiosemicarbazide.
11.7 Ammonium Ferric Sulfate.
11.8 Diacetyl monoxime.
11.9 Zinc acetate solution. weigh 22.0g of zinc acetate; dissolve it into water. Add 3mL of
glacial acetic acid; dilute it with water to 100mL.
11.10 Potassium ferrocyanide solution. weigh 10.6g of potassium ferrocyanide; dissolve it
into water. Dilute it with water to 100mL.
11.11 Acidic reagents. add about 100mL of distilled water into a 1L volumetric flask. Then
add 44mL of concentrated sulfuric acid and 66mL of 85% phosphoric acid. Cool it to room
temperature; add 80mg of thiosemicarbazide and 2g of ammonium ferric sulfate. Dissolve
them and dilute it with water to 1000mL. Preserve it in brown flask; put it in refrigerator for
later use.
11.12 Diacetyl monoxime solution (2%). weigh 2g of diacetyl monoxime; dissolve it into
distilled water to make the volume to be 100mL. Mix it uniformly for later use.
11.13 Urea reaction liquid. get 90mL of acidic reagent; add 10mL of diacetyl mo...