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This standard replaces GB/T 5009.125-2003 Determination of 6-caprolactam in Nylon 6 Resin and its Products, GB/T 23296.20-2009 Food Contact Materials - Polymer - Determination of Caprolactam and Caprolactam Salt in Food Simulants - Gas Chromatography and SN/T 2283-2009 Food Contact Materials - Polymer - Determination of Caprolactam and Caprolactam Salt in Food Simulants - Gas Chromatography.
The following main changes have been made with respect to GB/T 5009.125-2003 (the previous edition):
——This standard is renamed as National Food Safety Standard - Food Contact Materials and Articles - Determination of Caprolactam and Determination of Migration;
——Determination method of caprolactam is added.
National Food Safety Standard
Food Contact Materials and Articles
Determination of Caprolactam and Determination of Migration
1 Scope
This standard specifies the determination method of caprolactam and migration in food contact materials and articles.
This standard is applicable to the determination of caprolactam and migration in food contact materials and articles.
Determination of Caprolactam
2 Principle
Extract the specimen with water, dissolve caprolactam in the extracting solution, filter through the membrane, detect with high performance liquid chromatograph equipped with ultraviolet detector, and carry out the quantative determination by external standard method.
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 Reagent
Acetonitrile (C2H3N, CAS No.: 75-05-8): chromatographically pure.
3.2 Standard products
3.2.1 Caprolactam (C6H11NO, CAS No.: 105-60-2): with purity≥99%, or reference material approved and awarded with reference material certificate by the State.
3.3 Preparation of standard solutions
3.3.1 Caprolactam standard stock solution
Weigh 100 mg caprolactam (accurate to 0.0001 g), dissolve with water, scale the volume to 100 mL, to prepare the stock solution with the concentration of 1000 mg/mL; the solution shall be kept sealed in a dark place at 4℃, with valid period of a month.
3.3.2 Caprolactam midst standard solution
Pipet 0.05 mL, 0.25 mL, 0.5 mL, 1.0 mL, 2.5 mL and 5.0 mL caprolactam standard stock solution respectively with the graduated pipette into six 10 mL volumetric flasks, scale the volume with water to obtain the intermediate standard solutions with concentrations of caprolactam as 5.0 mg/L, 25.0 mg/L, 50.0 mg/L, 100.0 mg/L, 250.0 mg/L and 500.0 mg/L respectively. The storage mode of the solutions is as specified in 3.3.1.
3.3.3 Caprolactam standard working solution
Accurately pipet 1.0 mL caprolactam intermediate standard solution into six 10 mL glass test tubes with stoppers respectively, add 4.0 mL water and mix well to obtain the caprolactam standard working solutions with concentrations of caprolactam as 1.0 mg/L, 5.0 mg/L, 10.0 mg/L, 20.0 mg/L, 50.0 mg/L and 100.0 mg/L respectively. The storage mode of the solutions is as specified 3.3.1.
4 Instruments and Apparatus
4.1 High performance liquid chromatograph: equipped with ultraviolet detector (UV).
4.2 Freezing grinder.
4.3 Analytical balance: with sensibility of 0.0001 g.
4.4 Glass test tube with stopper: 10 mL.
4.5 0.45 μm microfiltration membrane.
4.6 Thermostat water bath.
5 Analysis Steps
5.1 Treatment of specimen
Crush the specimen into portions with particle size less than 1 mm×1 mm with the freezing grinder or scissor or other cutting tool, and then weigh it; the sample shall not be heated and softened during cutting.
5.2 Preparation of specimen solution
Weigh 1.0 g crushed sample (accurate to 0.0001 g), put into the glass test tube with stopper, add 10 mL water and extract in boiling water bath for 40 min, cool it to ambient temperature and then take supernatant in 25 mL volumetric flask. Re-extract with 10 mL water according to the above method, merge two clear solutions, dilute with water to the scale, pipet 1 mL extracting solution and filter with 0.45 μm membrane for sample injection with high performance liquid chromatography. If the concentration of sample solution exceeds linear range, properly dilute it with water to make its concentration within the linear range.
5.3 Preparation of blank solution
Prepare according to the same identical analysis steps, reagents and consumption as those described in 5.2 except without addition of the specimen.
5.4 Reference conditions of chromatograph
5.4.1 Chromatographic column: C18 column with length of 250 mm, inner diameter of 4.6 mm and particle size of 5 μm.
5.4.2 Detector: with ultraviolet detection wavelength of 210 nm.
5.4.3 Mobile phase: acetonitrile-water (20+80).
5.4.4 Flow rate: 1.0 mL/min.
5.4.5 Injection volume: 10 μL.
5.5 Plotting of standard curve
Inject caprolactam standard working solution into the liquid chromatograph respectively according to the determination conditions listed in 5.4. Plot the standard work curve with the concentration of caprolactam in standard working solution as x-axis (mg/L) and the corresponding peak area of caprolactam as y-axis. See Figure A.1 for the standard chromatogram.
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 Other
9 Principle
10 Reagents and Materials
11 Instruments and Apparatus
12 Analysis Steps
13 Expression of Analysis Results
14 Accuracy
15 Other
Annex A Liquid Chromatogram of Standard Solution
