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GB 5009.241-2017

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GB 5009.241-2017 英文版 295 购买 现货,9秒内自动发货PDF,有增值税发票。 食品安全国家标准 食品中镁的测定 作废

   
标准详细信息 GB 5009.241-2017; GB5009.241-2017
中文名称: 食品安全国家标准 食品中镁的测定
英文名称: Food safety national standard -- Determination of magnesium in food
行业: 国家标准
中标分类: X09
字数估计: 8,882
发布日期: 2017-04-06
实施日期: 2017-10-06
旧标准 (被替代): GB/T 5009.90-2003部分; GB/T 9695.21-2008; GB/T 23375-2009部分; GB/T 14609-2008部分; GB/T 18932.12-2002部分; GB 5413.21-2010部分; NY/T 82.19-1988部分
标准依据: State Health and Family Planning Commission Notice No. 5 of 2017

GB 5009.241-2017
Food safety national standard -- Determination of magnesium in food
中华人民共和国国家标准
食品安全国家标准
食品中镁的测定
2017-04-06发布
2017-10-06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 5009.90-2003《食品中铁、镁、锰的测定》、GB/T 9695.21-2008《肉与肉制品
镁含量测定》、GB5413.21-2010《食品安全国家标准婴幼儿食品和乳品中钙、铁、锌、钠、钾、镁、铜和
锰的测定》、GB/T 23375-2009《蔬菜及其制品中铜、铁、锌、钙、镁、磷的测定》、GB/T 14609-2008《粮
油检验 谷物及其制品中铜、铁、锰、锌、钙、镁的测定 火焰原子吸收光谱法》、GB/T 18932.12-2002
《蜂蜜中钾、钠、钙、镁、锌、铁、铜、锰、铬、铅、镉含量的测定方法 原子吸收光谱法》、NY82.19-1988
《果汁测定方法 钙和镁的测定》中镁的测定方法。
本标准与GB/T 5009.90-2003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镁的测定”;
---样品前处理方法调整为湿法消解、微波消解、干法灰化和压力罐消解;
---样品测定保留火焰原子吸收光谱法,删除滴定法;
---增加电感耦合等离子体发射光谱法为第二法;
---增加电感耦合等离子体质谱法为第三法。
食品安全国家标准
食品中镁的测定
1 范围
本标准规定了食品中镁含量测定的火焰原子吸收光谱法、电感耦合等离子体发射光谱法和电感耦
合等离子体质谱法。
本标准适用于各类食品中镁含量的测定。
第一法 火焰原子吸收光谱法
2 原理
试样消解处理后,经火焰原子化,在285.2nm处测定吸光度。在一定浓度范围内镁的吸光度值与
镁含量成正比,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 盐酸(HCl)。
3.2 试剂配制
3.2.1 硝酸溶液(5+95):量取50mL硝酸,倒入950mL水中,混匀。
3.2.2 硝酸溶液(1+1):量取250mL硝酸,倒入250mL水中,混匀。
3.2.3 盐酸溶液(1+1):量取50mL盐酸,倒入50mL水中,混匀。
3.3 标准品
金属镁(Mg,CAS号:7439-95-4)或氧化镁(MgO,CAS号:1309-48-4):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镁标准溶液。
3.4 标准溶液配制
3.4.1 镁标准储备液(1000mg/L):准确称取0.1g(精确至0.0001g)金属镁或0.1658g(精确至
0.0001g)于800℃±50℃灼烧至恒重的氧化镁,溶于2.5mL盐酸溶液(1+1)及少量水中,移入100mL
容量瓶,加水至刻度,混匀。
3.4.2 镁标准中间液(10.0mg/L):准确吸取镁标准储备液(1000mg/L)1.00mL,用硝酸溶液(5+95)
定容到100mL容量瓶中,混匀。
3.4.3 镁标准系列溶液:吸取镁标准中间液0mL、2.00mL、4.00mL、6.00mL、8.00mL和10.0mL于
100mL容量瓶中用硝酸溶液(5+95)定容至刻度。此镁标准系列溶液的质量浓度分别为0mg/L、
0.200mg/L、0.400mg/L、0.600mg/L、0.800mg/L和1.00mg/L。
注:可根据仪器的灵敏度及样品中镁的实际含量确定标准系列溶液中镁的质量浓度。
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:配火焰原子化器,镁空心阴极灯。
4.2 分析天平:感量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 恒温干燥箱。
4.7 压力消解罐:配聚四氟乙烯消解内罐。
4.8 马弗炉。
5 分析步骤
5.1 试样制备
注:在采样和制备过程中,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,再补加硝酸,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25mL,混匀备用。同时做试剂空白试验。亦可采
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,消解条件可参考附录A。冷却后取出消解
罐,在电热板上于140℃~160℃赶酸至0.5mL~1mL。消解罐放冷后,将消化液转移至25mL容量
瓶中,用少量水洗涤消解罐2~3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。
5.2.3 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。
后将消化液转移至25mL容量瓶中,用少量水洗涤内罐和内盖2~3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,将
坩埚在电热板上缓慢加热,微火碳化至不再冒烟。碳化后的试样放入马弗炉中,于550℃灰化4h。若
灰化后的试样中有黑色颗粒,应将坩埚冷却至室温后加少许硝酸溶液(5+95)润湿残渣,在电热板小火
蒸干后置马弗炉550℃继续灰化,直至试样成白灰状。在马弗炉中冷却后取出,冷却至室温,用2.5mL
硝酸溶液(1+1)溶解,并用少量水洗涤坩埚2~3次,合并洗涤液于容量瓶中并定容至25mL,混匀备
用。同时做试剂空白试验。
5.3.1 仪器参考条件
根据各自仪器性能调至最佳状态。参考条件为:空气-乙炔火焰,波长285.2nm,狭缝0.2nm,灯电
流5mA~15mA。
5.3.2 标准曲线的制作
将镁标准系列溶液按质量浓度由低到高的顺序分别导入火焰原子化器后测其吸光度值,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
在与测定标准溶液相同的实验条件下,将空白溶液和试样溶液分别导入原子化器测其吸光度值,与
标准系列比较定量。
试样中镁的含量按式(1)计算:
X=
(ρ-ρ0)×V
(1)
式中:
X ---试样中镁的含量,单位为毫克每千克或毫克每升(mg/kg或mg/L);
ρ ---试样溶液中镁的质量浓度,单位为毫克每升(mg/L);
ρ0---空白溶液中镁的质量浓度,单位为毫克每升(mg/L);
V ---试样消化液的定容体积,单位为毫升(mL);
当镁含量≥10.0mg/kg(或 mg/L)时,计算结果保留三位有效数字,当镁含量<10.0mg/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10%。
8 其他
当称样量为1g(或1mL),定容体积为25mL时,方法的检出限为0.6mg/kg(或0.6mg/L),定量
限为2.0mg/kg(或2.0mg/L)。
第二法 电感耦合等离子体发射光谱法
见GB 5009.268。
见GB 5009.268。
附 录 A
微波消解升温程序
微波消解升温程序见表A.1。
表A.1 微波消解升温程序
步骤
设定温度
升温时间
min
min

GB 5009.241-2017
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
National Food Safety Standard -
Determination of Magnesium in Food
食品安全国家标准 食品中镁的测定
ISSUED ON. APRIL 06, 2017
IMPLEMENTED ON. OCTOBER 06, 2017
Issued by. National Health and Family Planning Commission of PRC;
China Food and Drug Administration.
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Table of Contents
Foreword ... 3
1 Scope ... 4
2 Principle ... 4
3 Reagents and Materials ... 4
4 Apparatus ... 5
5 Analytical Procedures ... 6
6 Expression of Analytical Results ... 8
7 Precision ... 8
8 Others ... 8
Appendix A Microwave Digestion and Temperature-Rise Program ... 10
Foreword
This Standard replaced the determination of magnesium in the following standards
such as GB/T 5009.90-2003 Determination of iron, Magnesium and Manganese in
Foods, GB/T 9695.21-2008 Meat and Meat Products - Determination of Magnesium,
GB 5413.21-2010 National Food Safety Standard – Determination of Calcium, Iron,
Zinc, Sodium, Potassium, Magnesium, Copper and Manganese in Foods for Infants
and Young Children, Milk and Milk Products, GB/T 23375-2009 Determination of
Copper, Iron, Zinc, Calcium, Magnesium and Phosphorus Content in Vegetables and
Derived Products, GB/T 14609-2008 Inspection of Grain and Oils - Determination of
Copper, Iron, Manganese, Zinc, Calcium, Magnesium In Cereals and Derived Products
by Atomic Absorption and Flame Spectrophotometry, GB/T 18932.12-2002 Method for
the Determination of Potassium, Sodium, Calcium, Magnesium, Zine, Iron, Copper,
Manganese, Chromium, Lead, Cadmium Contents in Honey - Atomic Absorption
Spectrometry, NY 82.19-1988 Determination of Calcium and Magnesium in Fruit Juice.
Compared with GB/T 5009.90-2003, this Standard has the major changes as follows.
--- Modify the standard name into “National Food Safety Standard – Determination
of Magnesium in Food”;
--- Adjust the sample pre-treatment into wet digestion, microwave digestion, dry
ashing and pressure tank digestion;
--- Retain the flame atomic absorption spectrometry, and delete titration for sample
determination;
--- Add inductively coupled plasma emission spectrometry as the second method;
--- Add inductively coupled plasma mass spectrometry as the third method.
National Food Safety Standard -
Determination of Magnesium in Food
1 Scope
This Standard specifies use flame atomic absorption spectrometry, inductively coupled
plasma emission spectrometry, and inductively coupled plasma mass spectrometry to
determine the magnesium in food.
This Standard is applicable to the determination of magnesium in various foods.
The First Method of Flame Atomic Absorption Spectrometry
2 Principle
After digestion, the sample was flame atomized, then measure the absorbance at
285.2nm. In a certain concentration range, the magnesium absorbance value is
proportional to the magnesium content; compare with the standard series and then
quantify.
3 Reagents and Materials
Unless otherwise is specified, the reagents used in this method shall be guarantee
reagent; while water used in this method shall be Class-II water stipulated in GB/T
6682.
3.1 Reagents
3.1.1 Nitric acid (HNO3).
3.1.2 Perchloric acid (HClO4).
3.13 Hydrochloric acid (HCl).
3.2.1 Nitric acid solution (5+95). take 50mL of nitric acid; pour into 950mL of water;
mix evenly.
nitric acid; then digest the specimen as per the microwave digestion operation steps;
the digestion conditions can refer to Appendix A. After cooling off, take out the digestion
tank, put on the electric hot plate at 140°C~180°C to catch acid to 0.5mL ~ 1mL. After
the digestion tank is allowed to cool off, transfer the digestion solution into 25mL
volumetric flask; use a small amount of water to wash the digestion tank for 2~3 times;
combine the washing liquid into the volumetric flask; then use water to make constant
volume to the scale; mix evenly for spare-use. Meanwhile, do the blank teste of
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
acid. Cover the inner cap, tighten the stainless-steel jacket; place into the constant-
temperature drying oven; maintain for 4h~5h at 140°C~160°C. Slowly loosen the outer
tank after cooling; take out the digestion inner tank; place onto the adjustable electric
hot plate, then expel the acid to about 1mL at 140°C~160°C. After cooling, transfer the
digestion solution to the 25mL volumetric flask; use a small amount of water to wash
the inner tank and inner cap for 2~3 times; combine the washing liquid into the
spare-use. Meanwhile do the blank test.
5.2.4 Dry ashing
Take 0.5g~5g (accurate to 0.001g) of solid specimen or accurately pipette
0.500mL~10.0mL of liquid specimen into the crucible; slowly heat the crucible onto the
electric hot plate; carbonize with slight fire to no longer smoke. After carbonizing, place
the specimen into the muffle furnace; ashing for 4h at 550°C. If the specimen after
ashing has the black participles; cool off the crucible to the room temperature; add
small amount of nitric acid (5+95) to moisten the residue; after evaporating on the
electric hot plate with small fire, place it onto the muffle furnace to continue ashing at
it out; cool off to the room temperature; use 2.5mL of nitric acid (1+1) to dissolve; use
small amount of water to wash crucible for 2~3 times; combine the washing liquid into
the volumetric flask; make constant volume to 25mL; mix evenly for spare-use.
Meanwhile, do the blank test.
5.3 Determination
5.3.1 Instrument reference conditions
According to the performance of their instruments adjusted to the best condition,
reference conditions. air-acetylene flame, wavelength 285.2mm, slit 0.2nm, lamp
current 5mA~15mA.
   
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