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食品安全国家标准 食品接触材料及制品 发泡聚苯乙烯成型品中二氟二氯甲烷的测定
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GB 31604.22-2016
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标准编号: GB 31604.22-2016 (GB31604.22-2016)
中文名称: 食品安全国家标准 食品接触材料及制品 发泡聚苯乙烯成型品中二氟二氯甲烷的测定
英文名称: Method for analysis of hygienic standard of products of foamed polystyrene for food packaging
行业: 国家标准
中标分类: X09
字数估计: 6,635
发布日期: 2016-10-19
实施日期: 2017-04-19
旧标准 (被替代): GB/T 5009.100-2003
标准依据: 国家卫生和计划生育委员会公告2016年第15号
GB 31604.22-2016: 食品安全国家标准 食品接触材料及制品 发泡聚苯乙烯成型品中二氟二氯甲烷的测定
GB 31604.22-2016 英文名称: Method for analysis of hygienic standard of products of foamed polystyrene for food packaging
1 范围
本标准规定了发泡聚苯乙烯成型品中二氟二氯甲烷的测定方法。
本标准适用于发泡聚苯乙烯成型品中二氟二氯甲烷的测定。
2 原理
根据气体有关定律,将试样放入密封平衡瓶中,用溶剂溶解。在一定温度下,二氟二氯甲烷扩散,达
到平衡时,取液上气体注入气相色谱仪中测定。
3 试剂和材料
除非另有说明,本方法所用试剂均为分析纯,水为GB/T 6682规定的二级水。
3.1 试剂
3.1.1 N,N-二甲基乙酰胺(C4H9NO):色谱纯。
3.2 标准品
二氟二氯甲烷(CCl2F2)(CAS号:75-71-8):纯度 >99%。
3.3 标准溶液的制备
3.3.1 二氟二氯甲烷标准储备液(100μg/mL):准确称取二氟二氯甲烷标准品1mg(精确至0.01mg)
于10mL棕色容量瓶中,用N,N-二甲基乙酰胺溶解定容至刻度,混匀。于4℃保存,保存期为1年。
3.3.2 二氟二氯甲烷标准中间液(10μg/mL):准确移取二氟二氯甲烷储备溶液1mL于10mL棕色容
量瓶中,用N,N-二甲基乙酰胺稀释至刻度,混匀。于4℃保存,保存期为6个月。
3.3.3 二氟二氯甲烷标准工作液(1μg/mL):准确移取二氟二氯甲烷中间溶液1mL于10mL棕色容
量瓶中,用N,N-二甲基乙酰胺稀释至刻度,混匀。于4℃保存,保存期为3个月。
4 仪器和设备
4.1 气相色谱仪(GC):附氢火焰离子化检测器(FID)。
4.2 电子天平:感量为1mg和0.01mg。
4.3 恒温水浴装置:精度1℃。
4.4 平衡瓶:20mL。
4.5 气密针:1.0mL。
5 分析步骤
5.1 试样处理
将发泡聚苯乙烯成型品剪成3mm×3mm碎屑,用四分法取样,称取0.3g(精确到0.001g)放入平
衡瓶中。加入3mLN,N-二甲基乙酰胺溶解,立即盖塞,轻轻摇匀,放入65℃恒温水浴中平衡15min,
取1mL气体供气相色谱仪测定。
5.2 仪器参考条件
a) 色谱柱:6%腈丙苯基-94%二甲基聚硅氧烷毛细管色谱柱,柱长30m,内径0.32mm,膜厚
0.18μm,或相当者;
b) 柱温:初始温度50℃,保持5min,以20℃/min升温至250℃,保持2.5min;
c) 进样口温度:250℃;
d) 检测器温度:300℃;
e) 载气:氮气,纯度大于或等于99.999%;恒流模式;流速:1.0mL/min;
f) 进样量:1.0mL,分流进样,分流比为20∶1;
g) 尾吹气:氮气,60mL/min。
5.3 标准曲线的制作
在5个平衡瓶中各加入3mLN,N-二甲基乙酰,盖塞,用微量注射器取0μL、3μL、15μL、30μL、
150μL、300μL二氟二氯甲烷标准工作液(1μg/mL)通过胶塞注入瓶中,轻轻摇匀放入65℃恒温水浴
中平衡15min,即标准曲线浓度为0ng/mL、1ng/mL、5ng/mL、10ng/mL、50ng/mL、100ng/mL。
分别取液上气1mL注入气相色谱仪中,以二氟二氯甲烷含量为横坐标,峰面积为纵坐标绘制标准曲
线。二氟二氯甲烷标准溶液的气相色谱图参见图A.1。
5.4 试样溶液的测定
手动或自动将含有1mL试样的液上气注入气相色谱仪中进行测定,得到峰面积,根据标准曲线得
到试样溶液中二氟二氯甲烷的含量。同时做空白试验。
6 分析结果的表述
试样中二氟二氯甲烷含量按式(1)计算:
计算结果需扣除空白值,结果保留三位有效数字。
7 精密度
在重复性条件下获得的两次独立测定结果的绝对差值不得超过算术平均值的20%。
8 其他
按照本标准规定的取样量,本方法对二氟二氯甲烷的检出限为0.001mg/kg,定量限为0.01mg/kg。
GB 31604.22-2016
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
National Food Safety Standard - Food Contact Materials
and Articles - Determination of Dichlorodifluoromethane
in Products of Foamed Polystyrene
ISSUED ON. OCTOBER 19, 2016
IMPLEMENTED ON. APRIL 19, 2017
Issued by. National Health and Family Planning Commission of the PRC
Table of Contents
Foreword . 3
1 Scope .. 4
2 Principles . 4
3 Reagents and materials .. 4
4 Instruments and equipment . 5
5 Analytical procedures . 5
6 Analysis results expression . 6
7 Precision. 7
8 Others . 7
Appendix A Gas chromatogram of dichlorodifluoromethane standard solution 8
National Food Safety Standard - Food Contact Materials
and Articles - Determination of Dichlorodifluoromethane
in Products of Foamed Polystyrene
1 Scope
This Standard specifies the method for determination of
dichlorodifluoromethane in products of foamed polystyrene.
This Standard applies to the determination of dichlorodifluoromethane in
products of foamed polystyrene.
2 Principles
According to relevant gas law, PLACE the sample in a sealed equilibration flask;
and USE a solvent to dissolve. At a certain temperature,
dichlorodifluoromethane diffuses. When it reaches an equilibration, TAKE the
head space gas and INJECT it into gas chromatograph for determination.
3 Reagents and materials
Unless otherwise stated, the reagents used in this method are analytically pure.
The water is the Grade II water specified in GB/T 6682.
3.1 Reagents
3.1.1 N, N-dimethylacetamide (C4H9NO). chromatographically pure.
3.2 Standard
Dichlorodifluoromethane (CCl2F2) (CAS Number. 75-71-8). The purity>99%.
3.3 Preparation of standard solutions
3.3.1 Standard stock solution of dichlorodifluoromethane (100 μg/mL).
Accurately WEIGH 1 mg (accurate to 0.01 mg) of dimethylacetamide standard
in a 10 mL brown volumetric flask; USE N, N-dimethylacetamide to dissolve and
dilute to volume; and MIX well. At 4 °C, STORE it for 1 year.
c) Inlet temperature. 250 °C;
d) Detector temperature. 300 °C;
e) Carrier gas. nitrogen; the purity is greater than or equal to 99.999%.
Constant current mode; flow rate. 1.0 mL/min;
f) Injection volume. 1.0 mL, split injection; the split ratio is 20.1;
g) Make-up gas. nitrogen, 60 mL/min.
5.3 Making of standard curve
ADD 3 mL of N, N-dimethylacetamide in each of 5 equilibration flasks; CAP the
plugs; USE a microsyringe to take 0 μL, 3 μL, 15 μL, 30 μL, 150 μL, 300 μL of
standard working solution of dichlorodifluoromethane (1 μg/mL) and INJECT
into the flasks through rubber plug; gently SHAKE well and PUT in a constant
temperature water bath at 65 °C to equilibrate for 15 min. The standard curve
concentrations are 0 ng/mL, 1 ng/mL, 5 ng/mL, 10 ng/mL, 50 ng/mL,100 ng/mL.
Respectively TAKE 1 mL of the head space gas and INJECT into gas
chromatograph; TAKE the dichlorodifluoromethane content as the abscissa;
TAKE the peak area as the ordinate and DRAW standard curve. The gas
chromatogram of dichlorodifluoromethane standard solution is as shown in
Figure A.1.
5.4 Determination of sample solution
Manually or automatically INJECT the head space gas, which contains 1 mL of
the sample, into gas chromatograph to determine; and OBTAIN the peak area.
According to the standard curve, OBTAIN the content of
dichlorodifluoromethane in the sample solution. At the same time, CARRY out
blank test.
The content of dichlorodifluoromethane in the sample is calculated according
to the equation (1).
Where.
X - The content of dichlorodifluoromethane in the sample, in micrograms per
kilogram (mg/kg);
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