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This standard replaces SN/T 2828-2011 Food Contact Materials for Export - Wood Materials - Determination of Creosote in Cork - Gas Chromatography-Mass Spectrometry Method.
The following changes have been made with respect to SN/T 2828-2011 (the previous edition):
——This standard is renamed as "National Food Safety Standard - Food Contact Materials and Articles - Determination of Creosote in Cork";
——As for the quantitative method, single point method is replaced by standard curve method.
National Standard for Food Safety
Food Contact Materials and Articles
Determination of Creosote in Cork
1 Scope
This standard specifies the gas chromatography-mass spectrometry determination method for creosote in cork, the food contact material.
This standard is applicable to the determination of creosote in cork, the food contact material.
2 Principle
Extract the creosote in the specimen by the Soxhlet extractor with absolute ethanol, condense the extracting solution and scale the volume. Filter the extracting solution through the organic microporous filter membrane (0.45μm) and determination it with the gas chromatography-mass spectrometer (GC-MS), carry out the qualitative determination by retention time.
3 Reagents and Materials
Unless otherwise specified, analytically-pure reagents and Class-I water (defined in GB/T 6682) are adopted for the purpose of this method.
3.1 Reagents
Absolute ethanol (CH3CH2OH).
3.2 Standard product
Creosote standard product: with purity not less than 98%; see Annex A.
3.3 Preparation of standard solutions
3.3.1 Preparation of standard stock solution
Accurately weigh an adequate amount of creosote standard product respectively and prepare the standard stock solution with concentration of 100μg/mL with absolute ethanol.
3.3.2 Preparation of standard working solution
Take the standard stock solution and dilute it with absolute ethanol into standard working solutions with concentrations of 0.01μg/mL, 0.02μg/mL, 0.05μg/mL, 0.1μg/mL and 0.2μg/mL level by level, or prepare it into standard working solution with appropriate concentration as required.
Note: the standard stock solution shall be kept in the refrigerator at 0~4℃, with validity period of 6 months.
4 Instruments and Apparatus
4.1 Gas chromatograph-mass spectrometer.
4.2 Soxhlet extractor: 150mL.
4.3 Rotatory evaporator.
4.4 Cutting grinder.
4.5 Organic system microporous filter membrane: with pore diameter of 0.45μm.
5 Analysis Steps
5.1 Specimen preparation
Take an appropriate amount of cork sample, cut and grind the sample with the cutting grinder into powder with particle size not exceeding 1mm, mix uniformly and sufficiently, store it in a sealed container and preserve it from light.
5.2 Specimen extraction
Accurately weigh 2g (accurate to 1 mg) of specimen and put it into the paper drum of the Soxhlet extractor (150mL), add 80mL of absolute ethanol into a round-bottom flask (150mL), extract for 4h at 80℃～95℃; the internal reflux times shall not be less than 4 within 1h. After cooling, carry out rotatory evaporation with the rotatory evaporator at 50℃ until about 5mL left and then transfer it with absolute ethanol and scale the volume to 10mL. Filter the test solution through the organic system filter membrane for gas chromatography-mass spectrometry determination.
5.3 Determination
5.3.1 Reference conditions of the instrument
5.3.1.1 Reference conditions of the gas chromatograph-mass spectrometer
The following parameters are for reference; see Annex B for specific examples.
a) Chromatographic column: quartz capillary column;
b) Carrier gas: He, with purity ≥ 99.999 %;
c) Temperature programming;
d) Sample injection mode: splitless injection;
e) Ionization method: EI;
f) Electron energy: 70eV;
g) Determination mode: selected ion monitoring (SIM);
5.3.1.2 Testing by gas chromatography-mass spectrometry and confirmation
During sample determination, the corresponding target object is judged to exist in the sample if the retention time of the detected chromatographic peak is consistent with that of standard sample, all the selected ions appear in the mass spectrogram of the sample after background deduction, and the abundance ratio of the ion and that of the standard product are within permissible range (see Table 1 for the permissible range).
Foreword i
1 Scope
2 Principle
3 Reagents and Materials
4 Instruments and Apparatus
5 Analysis Steps
6 Expression of Analysis Results
7 Accuracy
8 Others
Annex A Name, CAS No., Chemical Structural Formula and Molecular Formula of the Nine Kinds of Creosote Compound
Annex B Example for Determination of Nine Kinds of Creosote Compound
