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This standard replaces SN/T 2890-2011 Food Contact Materials for Export - Polymers - Determination of Triethylamine and Tributylamine in Polycarbonate Resin and Its Products - Gas Chromatography.
The following main changes have been made with respect to SN/T 2890-2011 (the previous edition):
——This standard is renamed as "National Food Safety Standard - Food Contact Materials and Articles - Determination of Triethylamine and Tributylamine".
——The requirement of "plastic containers and transfer appliances shall not be used in the test" is added;
——"Measuring cylinder with stopper" in former standard is changed into "graduated centrifuge tube with stopper".
National Food Safety Standard
Food Contact Materials and Articles
Determination of
Triethylamine and Tributylamine
1 Scope
This standard specifies the gas chromatography for the determination of the contents of triethylamine and tributylamine in food contact materials and articles.
This standard is applicable to the determination of triethylamine and tributylamine in polycarbonate food contact materials and articles.
2 Principle
After dissolving the sample with dichloromethane, add in acetone to precipitate the polymer resin; after concentration and scaling of the volume, carry out determination by gas chromatography and quantative determination by external standard method.
3 Reagents and Materials
Unless otherwise specified, analytically-pure reagents are adopted for the purpose of this method. Plastic containers and transfer appliances shall not be used in the test.
3.1 Reagents
3.1.1 Dichloromethane (CH2Cl2).
3.1.2 Acetone (C3H6O).
3.2 Standard products
3.2.1 Triethylamine (C6H15N, CAS No.: 121-44-8): with purity ≥99%, or reference material approved and awarded with reference material certificate by the State.
3.2.2 Tributylamine (C12H27N, CAS No.: 121-44-8): 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 Standard stock solution
Accurately weigh 10 mg of triethylamine and 10 mg of tributylamine (accurate to 0.1 mg), put into a beaker (50mL), and add in about 30mL of dichloromethane; transfer into a volumetric flask (100mL) after dissolution, scale the volume with dichloromethane and shake well, and then obtain the standard stock solution. The standard stock solution shall be sealed in dark place at 4℃, with validity period of one month.
3.3.2 Standard working solution
Transfer 4.00 mL of standard stock solution, dilute it to 100mL with dichloromethane, scale the volume and shake well; transfer 1.00 mL, 2.00 mL, 3.00 mL, 4.00 mL and 5.00 mL of the diluted solutions into five different volumetric flasks (20mL) respectively, scale the volume with dichloromethane and shake well, and then obtain the standard working solution with the concentration of 0.2 mg/L, 0.4 mg/L, 0.6 mg/L, 0.8 mg/L and 1.0 mg/L respectively. The standard working solution shall be prepared immediately before use.
4 Instruments and Apparatus
4.1 Gas chromatograph: equipped with nitrogen-phosphorous detector.
4.2 Analytical balance or electronic balance: with the sensibility of 0.1 mg.
4.3 Centrifuger: 3,000 r/min.
4.4 Rotary evaporator.
4.5 Graduated centrifuge tube with stopper: 2mL or 5mL.
4.6 Syringe-driven filter for organic phase: 0.22 μm.
5 Analysis Steps
5.1 Preparation of specimen
Cut the specimen into those with particle size less than 5 mm×5 mm with the cutting tool firstly, and then weigh them; the sample shall not be heated and softened during cutting.
5.2 Preparation of specimen solution
Weigh 1 g of specimen (accurate to 0.001 g), put it into a conical flask (200mL), and add in 20mL of dichloromethane; after the sample is dissolved completely, shake the conical flask and dropwise add in 100mL of acetone with separating funnel simultaneously; shake the solution in the flask well after finishing dropping, centrifuge for 10 min, and take the supernatant to carry out rotary evaporation until its volume is about 1mL; transfer the concentrated solution into the graduated centrifuge tube with stopper completely, scale the volume to 2.0 mL with dichloromethane, and obtain the specimen solution for determination of gas chromatography.
Note 1: the solution may be centrifuged in several times, and the centrifuged supernatant is required to be combined.
Note 2: if it is slightly turbid in specimen solution, syringe-driven filter for organic phase may be adopted for filtration and then gas chromatograph may be adopted for determination.
5.3 Blank test
The analysis steps, reagents and dosage identical with those in 5.2 are adopted, with parallel operation carried out except the specimen is not added.
5.4 Reference conditions of gas chromatography
5.4.1 Chromatographic column: ZB-5 quartz capillary column, with length of 30 m, inner diameter of 0.32 mm and film thickness of 5 μm; or equivalent;
5.4.2 Column temperature: maintain the initial temperature 40℃ for 5 min, then raise to 250℃ at a rate of 20℃/min and maintain for 2.5 min;
5.4.3 Temperature of injection port: 200℃;
5.4.4 Temperature of detector: 250℃;
5.4.5 Carrier gas: nitrogen (with purity≥99.999%); with flow rate of 1.0mL/min;
5.4.6 Hydrogen flow rate of detector: 3 mL/min;
5.4.7 Air flow rate of detector: 60 mL/min;
5.4.8 Injection volume: 1 μL;
5.4.9 Injection mode: splitless injection.
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 Gas Chromatogram of Triethylamine and Tributylamine
