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GB 5009.138-2017

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标准详细信息 GB 5009.138-2017; GB5009.138-2017
中文名称: 食品安全国家标准 食品中镍的测定
英文名称: Food safety national standard -- Determination of nickel in food
行业: 国家标准
中标分类: X09
字数估计: 9,931
发布日期: 2017-04-06
实施日期: 2017-09-17
旧标准 (被替代): GB/T 5009.138-2003
标准依据: State Health and Family Planning Commission Notice No. 5 of 2017

GB 5009.138-2017
Food safety national standard -- Determination of nickel in food
中华人民共和国国家标准
食品安全国家标准
食品中镍的测定
2017-04-06发布
2017-09-17实施
中华人民共和国国家卫生和计划生育委员会
国 家 食 品 药 品 监 督 管 理 总 局 发 布
前言
本标准代替GB/T 5009.138-2003《食品中镍的测定》。
本标准与GB/T 5009.138-2003相比,主要变化如下:
---标准名称修改为“食品安全国家标准食品中镍的测定”;
---修订了样品前处理部分内容,增加了微波消解法和干法灰化;
---优化了石墨炉原子吸收光谱法的测定条件,增加了基体改进剂;
---增加了石墨炉原子吸收光谱法的方法定量限;
---删除了第二法比色法。
食品安全国家标准
食品中镍的测定
1 范围
本标准规定了食品中镍含量测定的石墨炉原子吸收光谱法。
本标准适用于各类食品中镍含量的测定。
2 原理
试样消解处理后,经石墨炉原子化,在232.0nm处测定吸光度。在一定浓度范围内镍的吸光度值
与镍含量成正比,与标准系列比较定量。
3 试剂和材料
除非另有说明,本方法所用试剂均为优级纯,水为GB/T 6682规定的二级水。
3.1 试剂
3.1.1 硝酸(HNO3)。
3.1.2 高氯酸(HClO4)。
3.1.3 硝酸钯[Pd(NO3)2]。
3.1.4 磷酸二氢铵(NH4H2PO4)。
3.2 试剂配制
3.2.1 硝酸溶液(0.5mol/L):吸取硝酸3.2mL,加水稀释至100mL,混匀。
3.2.2 硝酸溶液(1+1):量取500mL硝酸,与500mL水混合均匀。
3.2.3 磷酸二氢铵-硝酸钯溶液:称取0.02g硝酸钯,分几次加入少量硝酸溶液(1+1)溶解后,再加入
2g磷酸二氢铵,用硝酸溶液(1+1)定容至100mL,混匀。
3.3 标准品
金属镍(Ni,CAS号:7440-02-0):纯度>99.99%,或经国家认证并授予标准物质证书的一定浓度的
镍标准溶液。
3.4 标准溶液配制
3.4.1 镍标准储备液(1000mg/L):准确称取1g(精确至0.0001g)金属镍,加入30mL硝酸溶液
(1+1),加热溶解,移入1000mL容量瓶中,加水稀释至刻度,混匀。
3.4.2 镍标准中间液(1.00mg/L):准确吸取镍标准储备液(1000mg/L)0.1mL于100mL容量瓶中,
加硝酸溶液(0.5mol/L)定容至刻度,混匀。
3.4.3 镍标准系列溶液:分别准确吸取镍标准中间液0mL、0.500mL、1.00mL、2.00mL、4.00mL和
5.00mL于100mL容量瓶中,加硝酸溶液(0.5mol/L)稀释至刻度,混匀。此镍标准系列溶液的质量浓
度分别为0μg/L、5.00μg/L、10.0μg/L、20.0μg/L、40.0μg/L和50.0μg/L。
注:可根据仪器的灵敏度及样品中镍的实际含量确定标准系列溶液中镍的质量浓度。
4 仪器和设备
注:所有玻璃器皿及聚四氟乙烯消解内罐均需硝酸溶液(1+5)浸泡过夜,用自来水反复冲洗,最后用水冲洗干净。
4.1 原子吸收光谱仪,配石墨炉原子化器,附镍空心阴极灯。
4.2 分析天平:感量为0.1mg和1mg。
4.3 可调式电热炉。
4.4 可调式电热板。
4.5 微波消解系统:配聚四氟乙烯消解内罐。
4.6 压力消解罐:配聚四氟乙烯消解内罐。
4.7 恒温干燥箱。
4.8 马弗炉。
5 分析步骤
5.1 试样制备
注:在采样和试样制备过程中,应避免试样污染。
5.1.1 粮食、豆类样品
样品去除杂物后,粉碎,储于塑料瓶中。
5.1.2 蔬菜、水果、鱼类、肉类等样品
样品用水洗净,晾干,取可食部分,制成匀浆,储于塑料瓶中。
5.1.3 饮料、酒、醋、酱油、食用植物油、液态乳等液体样品
将样品摇匀。
5.2 试样消解
5.2.1 湿法消解
称取固体试样0.2g~3g(精确至0.001g)或准确移取液体试样0.500mL~5.00mL于带刻度消化
管中,加入10mL硝酸、0.5mL高氯酸,在可调式电热炉上消解(参考条件:120℃/0.5h~1h、升至
180℃/2h~4h、升至200℃~220℃)。若消化液呈棕褐色,再加少量硝酸,消解至冒白烟,消化液呈
无色透明或略带黄色,取出消化管,冷却后用水定容至10mL,混匀备用。同时做试剂空白试验。亦可
采用锥形瓶,于可调式电热板上,按上述操作方法进行湿法消解。
5.2.2 微波消解
称取固体试样0.2g~0.8g(精确至0.001g)或准确移取液体试样0.500mL~3.00mL于微波消解
罐中,加入5mL硝酸,按照微波消解的操作步骤消解试样,消解条件参考附录A。冷却后取出消解罐,
在电热板上于140℃~160℃赶酸至1mL左右。消解罐放冷后,将消化液转移至10mL容量瓶中,用
少量水洗涤消解罐2次~3次,合并洗涤液于容量瓶中并用水定容至刻度,混匀备用。同时做试剂空白
5.2.3 压力罐消解
称取固体试样0.2g~1g(精确至0.001g)或准确移取液体试样0.500mL~5.00mL于消解内罐
中,加入5mL硝酸。盖好内盖,旋紧不锈钢外套,放入恒温干燥箱,于140℃~160℃下保持4h~5h。
冷却后缓慢旋松外罐,取出消解内罐,放在可调式电热板上于140℃~160℃赶酸至1mL左右。冷却
后将消化液转移至10mL容量瓶中,用少量水洗涤内罐和内盖2次~3次,合并洗涤液于容量瓶中并用
水定容至刻度,混匀备用。同时做试剂空白试验。
5.2.4 干法灰化
称取固体试样0.5g~5g(精确至0.001g)或准确移取液体试样0.500mL~10.0mL于坩埚中,小
火加热,炭化至无烟,转移至马弗炉中,于550℃灰化3h~4h。冷却,取出,对于灰化不彻底的试样,加
出,用适量硝酸溶液(1+1)溶解并用水定容至10mL。同时做试剂空白试验。
5.3 测定
5.3.1 仪器参考条件
根据各自仪器性能调至最佳状态。参考条件见附录B。
5.3.2 标准曲线的制作
按质量浓度由低到高的顺序分别将10μL镍标准系列溶液和5μL磷酸二氢铵-硝酸钯溶液(可根
据所使用的仪器确定最佳进样量)同时注入石墨炉,原子化后测其吸光度值,以质量浓度为横坐标,吸光
度值为纵坐标,制作标准曲线。
5.3.3 试样溶液的测定
溶液(可根据所使用的仪器确定最佳进样量)同时注入石墨炉,原子化后测其吸光度值,与标准系列比较
定量。
6 分析结果的表述
试样中镍的含量按式(1)计算:
X =
(ρ-ρ0)×V
m×1000
(1)
式中:
ρ ---试样溶液中镍的质量浓度,单位为微克每升(μg/L);
ρ0 ---空白溶液中镍的质量浓度,单位为微克每升(μg/L);
V ---试样消化液的定容体积,单位为毫升(mL);
m ---试样称样量或移取体积,单位为克或毫升(g或mL);
1000 ---换算系数。
当镍含量≥1.00mg/kg(或 mg/L)时,计算结果保留三位有效数字,当镍含量<1.00mg/kg
(或mg/L)时,计算结果保留两位有效数字。
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%。
当称样量为 0.5g(或 0.5 mL),定容体积为 10 mL 时,方法的检出限为 0.02 mg/kg
(或0.02mg/L),定量限为0.05mg/kg(或0.05mg/L)。
附 录 A
微波消解推荐升温程序
微波消解推荐升温程序如表A.1所示。
表A.1 微波消解推荐升温程序
步骤 设定温度/℃ 升温时间/min 恒温时间/min
附 录 B
石墨炉推荐升温程序
表B.1 石墨炉推荐升温程序
步 骤 程 序 温度/℃ 升温时间/s 保持/s 氩气流量/(L/min)
1 干燥
85 5 10 0.3
120 5 20 0.3
2 灰化
400 10 10 0.3
1000 10 10 0.3
3 原子化 2700 1 3 停气


GB 5009.138-2017
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
National Food Safety Standard
– Determination of Nickel in Food
食品安全国家标准 食品中镍的测定
ISSUED ON. APRIL 06, 2017
IMPLEMENTED ON. SEPTEMBER 17, 2017
Issued by. National Health and Family Planning Commission of PRC.;
China Food and Drug Administration.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Principle ... 4
3 Reagents and Materials ... 4
4 Instrument and Equipment ... 5
5 Analytical Procedures ... 6
6 Expression of Analytical Results ... 8
7 Precision ... 8
8 Others ... 8
Appendix A Recommended Temperature-Rise Procedures for Microwave
Digestion ... 9
Appendix B Recommended Temperature-Rise Procedures for Graphite
Furnace ... 10
National Food Safety Standard
– Determination of Nickel in Food
1 Scope
This Standard specifies using the graphite furnace atomic absorption spectrometry to
determine the nickel content in the food.
This Standard is applicable to determine the nickel content in various foods.
2 Principle
After the digestion of the sample, measure the absorbance at 232.0nm through the
atomization of the graphite furnace. In a certain concentration range, the nickel
absorbance value is proportional to the nickel content; quantify through the comparison
with the standard series.
3 Reagents and Materials
Unless otherwise specified, the reagents used in this method are guaranteed reagents;
while water is Class-II water specified in GB/T 6682.
3.1 Reagents
3.1.1 Nitric acid (HNO3).
3.1.2 Perchloric acid (HClO4).
3.1.3 Palladium nitrate [Pd(NO3)2].
3.1.4 Ammonium dihydrogen phosphate (NH4H2PO4).
3.2 Reagents preparation
3.2.1 Nitric acid solution (0.5mol/L). pipette 3.2mL of nitric acid; add water to dilute
to 100mL, mix evenly.
3.2.2 Nitric acid solution (1+1). weigh 500mL of nitric acid; mix with 500mL of water
evenly.
3.2.3 Ammonium dihydrogen phosphate – palladium nitrate solution. take 0.02g of
palladium nitrate; add small amount of nitric acid solution (1+1) by several times to
4.8 Muffle furnace.
5 Analytical Procedures
5.1 Specimen preparation
NOTE. during the sampling and specimen preparation period, the specimen contamination
shall be avoided.
5.1.1 Grains and beans samples
After removing the debris, crush the samples and store into the plastic bottles.
5.1.2 Vegetables, fruits, fish, meat and the like samples
Wash the samples with water, dry them; then take the edible part, and make into the
homogenate state, and store into the plastic bottles.
5.1.3 Drinks, wine, vinegar, soy sauce, edible vegetable oil, liquid milk and
other liquid samples
Shake the samples evenly.
5.2 Specimen digestion
5.2.1 Wet digestion
Take 0.2g~3g (accurate to 0.001g) of solid specimen or accurately pipette
0.500mL~5.00mL of liquid specimen into the digestion tube with scale; add 10mL of
nitric acid, 0.5mL of perchloric acid; digest on the adjustable electric hot furnace
(reference condition. 120°C/0.5h~1h, rise to 180°C/2h~4h, rise to 200°C~220°C). If
appears; then digestive juice is colorless and transparent or slightly yellow; take out
the digestion tube; after cooling off, use water to make constant volume to 10mL, mix
evenly and for later-use. Meanwhile do the blank test of the reagent. The conical flask
can also be used; perform the wet digestion on the adjustable electric hot plate
according to the above-mentioned method.
5.2.2 Microwave digestion
Take 0.2g~0.8g (accurate to 0.001g) of solid specimen or accurately pipette
0.500mL~3.00mL of liquid specimen into the microwave digestion tank; add 5mL of
nitric acid; digest the specimen according to the microwave digestion procedures; the
tank; expel acid on the electric hot plate at 140°C~160°C to 1mL or so. After the
digestion tank is cooling off, transfer the digestive juice into the 10mL volumetric flask;
use small amount of water to wash and digest the tank for twice and three times;
combine the washing liquids into the volumetric flask; use water to make constant
volume to the scale; mix evenly for later-use. Meanwhile do the blank test of the
reagent.
5.2.3 Pressure tank digestion
Take 0.2g~1g (accurate to 0.001g) of solid specimen or accurately pipette
0.500mL~5.00mL of liquid specimen into the digestion inner tank; add 5mL of nitric
temperature oven; maintain for 4h~5h at 140°C~160°C. After cooling, slowly loosen
the outer tank; take out the digestion inner tank; expel acid on the adjustable electric
hot plate at 140°C~160°C to 1mL or so. After cooling off, transfer the digestive juice
into the 10mL volumetric flask; use small amount of water to wash the inner tank and
inner cap for twice ~ three times; combine the washing liquids into the volumetric flask,
use water to make constant volume to the scale. Meanwhile do the blank test of the
reagent.
5.2.4 Dry ashing
Take 0.5g~5g (accurate to 0.001g) of solid specimen or accurately pipette
to smokeless; transfer into the muffle furnace to ash for 3h~4h at 550°C. After cooling
off, take out; for the specimen that is not ashed completely, add several drops of nitric
acid; heat on small fire; carefully dry it; then transfer into the 550°C muffle furnace;
continue to ash for 1h~2h till the specimen becomes the white ash state; cooling off,
take out; dissolve by appropriate amount of nitric acid solution (1+1); then use water
to make constant volume to 10mL. Meanwhile do the blank test of the reagent.
5.3 Determination
5.3.1 Instrument reference conditions
Adjust the instrument to the optical state according to its performance. The reference
5.3.2 Drawing of standard curve
Inject 10µL of nickel standard series solution and 5µL of ammonium dihydrogen
phosphate-palladium nitrate solution (the optical sample injection volume can be
determined according to the used instrument) into the graphite furnace at the same
time according to the order of mass concentration from low to high; after atomization,
measure the absorbance value; then draw the standard curve with mass concentration
as abscissa, and absorbance value as the ordinate.
5.3.3 Determination of specimen solution
   
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