GB 31604.21-2016

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GB 31604.21-2016
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
National food safety standard –
Food contact materials and articles –
Determination of migration of terephthalic acid
食品接触材料及制品
ISSUED ON. OCTOBER 19, 2016
IMPLEMENTED ON. APRIL 19, 2017
Issued by. National Health and Family Planning Commission of the
People's Republic of China
Table of Contents
Foreword . 3 
1 Scope .. 4 
2 Principle . 4 
3 Reagents and materials .. 4 
4 Apparatus . 6 
5 Analytical procedures . 6 
6 Expression of analysis results .. 8 
7 Confirmation . 8 
8 Precision . 8 
9 Others . 8 
Annex A Terephthalic acid standard substance chromatogram . 10 
Annex B Liquid chromatography-tandem mass spectrometry confirmation
reference conditions . 11 
Annex C Terephthalic acid multiple-reaction monitoring (MRM) chromatogram
. 13 
Foreword
This Standard replaces GB/T 23296.10-2009, Food contact materials - Polymer -
Determination of terephthalic acid in food simulants - High performance liquid
chromatography, and SN/T 2184-2008, Food contact materials - Polymer materials -
Determination of terephthalic acid in food simulants - HPLC.
Compared with GB/T 23296.10-2009 and SN/T 2184-2008, the major changes of this
Standard are as follows.
-- the standard name is changed into “National food safety standard - Food contact
materials and articles - Determination of migration of terephthalic acid”;
-- the preparation of food simulant test solution is changed;
-- the expression of analysis results is changed;
-- the detection limits and quantitation limits are changed.
National food safety standard –
Food contact materials and articles –
Determination of migration of terephthalic acid
1 Scope
This Standard specifies the method for the determination of migration of terephthalic
acid in food contact materials and articles.
This Standard applies to the determination of migration of terephthalic acid in food
contact materials and articles.
2 Principle
Terephthalic acid in food simulants is separated using high performance liquid
chromatograph and then tested using ultraviolet detector. The food simulants of water-
based, acidic and alcoholic types are sampled and tested directly; and the food
simulants of olive oil medium is extracted using diluted hydrochloric acid solution
before being sampled and tested. Phthalic acid is used as the internal standard and
the internal standard method is used for quantitation.
3 Reagents and materials
Unless indicated otherwise, all reagents used for this method are analytically pure and
the water is grade one water specified in GB/T 6682.
3.1 Reagents
3.1.1 Sodium acetate trihydrate (C2H3O2Na·3H2O).
3.1.2 Sodium bicarbonate (NaHCO3).
3.1.3 Normal heptane (n-C7H16).
3.1.4 Methyl alcohol (CH3OH). chromatographically pure.
3.1.5 Isopropyl alcohol (C3H8O).
3.1.6 Phosphoric acid (H3PO4).
water-based, acidic and alcoholic food simulants are respectively 0.0 mg/L, 0.8 mg/L,
1.6 mg/L, 4.0 mg/L, 8.0 mg/L and 16.0 mg/L; and the internal standard concentrations
are all 8.0 mg/L.
3.4.4 Olive oil medium standard working solution. weigh respectively 50 g of olive oil
to pour in six 250 mL separating funnels; accurately transfer 2.0 mL of terephthalic acid
standard intermediate solution in; add 50 mL of normal heptane after mixing up; and
then mix up. Then add 20 mL of sodium bicarbonate solution; fully shake up for 1 min;
and allow to stand for layering. Use a 100 mL beaker to collect the lower layer water
phase; then add 20 mL of sodium bicarbonate solution to extract the upper layer oil
phase once again. Allow to stand after shaking up, use a beaker to collect the lower
layer water phase after two phases separates; and combine the two water-phase
extraction solutions. Use an injection syringe or vacuum pump (flow velocity 10
mL/min~20 mL/min) to make the extraction solution pass through the solid-phase
extraction C18 column. Collect the filtrate in a 50 mL volumetric flask; add 1.0 mL of 50%
acetic acid solution; and use water to add to scale. Take 1 mL~2 mL of the filtrate to
filter using a filter membrane. The concentrations of the standard working solutions of
terephthalic acid are respectively 0 mg/kg, 0.8 mg/kg, 1.6 mg/kg, 4.0 mg/kg, 8.0 mg/kg
and 16.0 mg/kg; and the internal standard concentrations are all 8.0 mg/kg.
3.4.5 Phthalic acid internal standard stock solution (1 000 mg/L). accurately weigh
0.1 g (accurate to 0.1 mg) of phthalic acid standard substance; use 10 mL of isopropyl
alcohol to dissolve; and then transfer the solution to a 100 mL volumetric flask and add
isopropyl alcohol to scale. The period of validity is 6 months.
3.4.6 Terephthalic acid internal standard intermediate solution (200 mg/L). take 5 mL
of phthalic acid internal standard stock solution to pour into a 25 mL volumetric flask;
and use methyl alcohol to add to scale.
4 Apparatus
4.1 High performance liquid chromatograph. equipped with ultraviolet detector and
10 μL quantitative loops.
4.2 Analytical balance. of sensitivity 0.1 mg and 0.1 g.
4.3 pH meter.
4.4 Solid-phase extraction C18 column. octadecyl silane (ODS) 400 mg.
4.5 Hydrophilic microporous filter membrane. 0.45 μm.
5 Analytical procedures
5.1 Sample migration test
e) sample volume. 10 μL;
f) ultraviolet detector. of wavelength 242 nm.
5.4.2 Plotting of standard working curves
Carry out determination of standard working solutions in turn in accordance with the
determination conditions listed in 5.4.1. Plot respectively standard working curves
using the terephthalic acid concentrations in standard working solutions as the
abscissa, in mg/L or mg/kg, and the peak area ratio of terephthalic acid/phthalic acid
as the ordinate. For the standard solution chromatograms refer to Annex A.
5.4.3 Test solution determination
Inject blank solutions and food simulant test solutions in turn, deducting blank values;
and obtain the peak area ratio of terephthalic acid/phthalic acid.
6 Expression of analysis results
Obtain the terephthalic acid concentration of test solution from standard curves; and
calculate migration in accordance with GB 5009.156; and then obtain the migration of
terephthalic acid in food contact materials and articles. The calculation results are
rounded off to two significant digits.
7 Confirmation
When the above-mentioned results exceed specific migration limits, use the liquid
chromatography-tandem mass spectrometry or other effective methods for
confirmation. For the reference conditions for the liquid chromatography-tandem mass
spectrometry see Annex B and Annex C.
8 Precision
The absolute difference obtained from two independent determination results under
repeatable conditions shall not be 10% exceeding the arithmetic mean value.
9 Others
The detection limit for terephthalic acid in water-based, acidic and alcoholic simulants
is 0.3 mg/L; and the detection limit for terephthalic acid in olive oil simulants is 0.3
mg/kg.
The quantitation limit for terephthalic acid in water-based, acidic and alcoholic
simulants is 1.0 mg/L; and the quantitation limit for terephthalic acid in olive oil simulant