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GB 31604.26-2016: Food contact materials -- Determination of epichlorohydrin in plastics -- High performance liquid chromatography
GB 31604.26-2016
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
National Food Safety Standard - Food contact
materials and products - Determination of
epichlorohydrin and determination of migration
ISSUED ON. OCTOBER 19, 2016
IMPLEMENTED ON. APRIL 19, 2017
Issued by. National Health and Family Planning Commission of People's
Republic of China
Table of Contents
Foreword ... 3
1 Scope ... 4
Determination of epichlorohydrin ... 4
2 Principle... 4
3 Reagents and materials ... 4
4 Instruments and equipment ... 6
5 Analytical steps ... 7
6 Expression of the analytic result ... 10
7 Precision... 10
8 Others ... 10
Determination of migration of epichlorohydrin (gas chromatography-mass
spectrometry) ... 11
9 Principle... 11
10 Reagents and materials... 11
11 Instruments and equipment ... 14
12 Analytical steps ... 14
13 Expression of the analytic result ... 17
14 Precision ... 18
15 Others ... 18
Appendix A Micro distillation unit ... 19
Appendix B Liquid chromatogram of DAS derivatives of epichlorohydrin ... 20
Appendix C ... 23
Foreword
This standard replaces GB/T 23296.7-2009 "Food contact materials.
Determination of epichlorohydrin in plastics. High performance liquid
chromatography" and SN/T 2897-2011 “Food contact materials for export.
Metal materials. Determination of epichlorohydrin in coating. Gas
chromatography”.
In comparison with GB/T 23296.11-2009, the main differences of this
standard are as follows.
- Changed the name of the standard to "National Food Safety Standard -
Food contact materials and products - Determination of epichlorohydrin
and its migration";
- Added applicable scope;
- Revised the sample preparation method of coating;
- Added the determination method of the migration of epichlorohydrin in
food contacting materials and products.
National Food Safety Standard - Food contact
materials and products - Determination of
epichlorohydrin and determination of migration
1 Scope
This standard provides the determination method of epichlorohydrin in food
contact materials and products (plastics, paints, paper and cardboard) and
the determination method of migration.
This standard is applicable to the determination of epichlorohydrin in food
contact materials and products (plastics, paints, paper and cardboard) and
the determination of the migration of epichlorohydrin. The high performance
liquid chromatography (HPLC) is suitable for the determination of
epichlorohydrin in food contact materials and products (plastics, coatings,
paper products). The gas chromatography-mass spectrometry is suitable for
the determination of the migration of epichlorohydrin in food contact materials
and products (plastics, coatings, paper and cardboard).
Determination of epichlorohydrin
2 Principle
After extraction of epichlorohydrin from the sample by 1,4-dioxane, the extract
solution is distilled by a microdistillation unit. The epichlorohydrin in the
distilled liquid is derived and its derivatives are separated by liquid
chromatography. The content of epichlorohydrin derivatives is determined by
fluorescence detector and the content of epichlorohydrin in the sample can be
calculated. The external standard method is used for quantitative analysis.
3 Reagents and materials
Unless otherwise stated, the reagents used in this method shall be analytical
pure. The water shall be the primary water specified in GB/T 6682.
3.1 Reagents
3.1.1 Acetonitrile (C2H3N). chromatographic pure.
3.1.2 9,10-Sodium dimethoxanthrone-2-sulfonate (C16H13NaO5S), or
DAS-Na.
3.1.3 1,4-Dioxane (C4H8O2). purity≥ 99% and the water content< 0.01%.
3.1.4 Methanol (CH4O). chromatographic purity.
3.1.5 Strong acid cation exchange resin.
3.1.6 Nitrogen. purity greater than or equal to 99.9%.
3.1.7 Ice.
3.2 Reagent preparation
3.2.1 Methanol solution (80%, volume fraction)
Take 400mL of methanol and put in 500ml volumetric bottle. Meter the volume
with water.
3.2.2 9,10-Sodium dimethoxanthrone-2-sulfonate reagent (DAS reagent)
Use 200 mL methanol solution (80%, volume fraction) to activate about 50g
pre-treated strong acid cation exchange resin. Then filled resin to a glass
column with inner diameter of 1cm to 20cm high. Put aside to be used. Weigh
100mg of DAS-Na add to a beaker containing 20ml methanol, heat to
dissolve. Pour the solution through the strong acid cation exchange resin.
Complete all the solutions in 2 times or 3 times. Elute with methanol and
make the flow rate of the effluent at about 0.5mL/min, collect the eluent at pH
1~2 until the pH begins to rise. Dry the obtained eluent with nitrogen blower to
get the DAS reagent. The DAS reagent should be kept away from light and
validity period is 1 year.
3.2.3 DAS-Acetonitrile solution (5mg/mL)
Weigh 20mg (precision to 0.1mg) DAS reagent and dissolve in 4mL
acetonitrile. Prepare when needed; keep away from light.
3.3 Standard product
Epichlorohydrin (C3H5ClO, CAS No.. 106-89-8). purity>99%, or a standard
substance certified by the State and granted the standard substance
certificate.
3.4 Standard solution preparation
3.4.1 Epichlorohydrin standard reserve solution (1mg/mL)
Take 10.0mL of 1,4-dioxane that is not in contact with plastic, paper or coating
samples and put it into a 20mL sample bottle, add magnetic stirring rod, seal
with spacer and aluminum cap and mark the sample bottle as A0.
5.4 Distillation of 1,4- dioxane extract
Use the micro-distillation unit in figure A.1 to distill 1,4-dioxane extract and
collect the partial distillate. In figure A.1, bottle A are the sample bottles in
5.2.1, 5.2.2, 5.3 and 3.4.4, which contain 10mL sample extract solution, blank
solution and standard working solution respectively.
Take another 20mL sample bottles and mark at the volume of 3mL, then seal
with spacer and aluminum cap. Weigh the sealed sample bottle (precision to
0.1mg) and label as bottle B.
As shown in figure A.1, bottle A and bottle B are connected by a stainless
steel tube with polytetrafluoroethylene on the outside. The depth of the pipe
pierced into bottle A is 1cm~2cm and in bottle B is 3cm~4cm. To prevent the
inserted pipe from being blocked, prick a small hole on the bottle plug of the
sample bottle so that the steel pipe can quickly pierce into the bottle. Insert a
syringe needle on the bottle B's cover to avoid excessive pressure in the
bottle.
Place bottle A on a heating plate and put bottle B in a beaker containing a
mixture of ice water. Heat bottle A to boil the 1,4-dioxane extract, continue to
heat mildly and move the distilled1,4-dioxane extract to bottle B until the liquid
level reaches 3mL mark in bottle B. Remove bottle A from the heater and
remove the syringe needle and stainless steel tube from bottle B. Wipe dry
bottle B carefully with filter paper. Reweigh bottle B (precision to 0.1mg).
Calculate the volume of distillate according to the difference between the two
weights and the density of 1,4-dioxane.
The distillate can be stored for 2 weeks at 0°C~ 4°C.
5.5 Derivatization of epichlorohydrin
Open the aluminum cover of bottle B containing distillate solution, add 50μL
of DAS-acetonitrile solution (5mg/mL), seal with spacer and aluminum cap.
Place the sample bottle in 75°C oven for 17h±1h, then cool the derivative
solution in room temperature and filter with 0.22μm microporous membrane.
Set aside the filtrate to b...