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食品安全国家标准 食品中镁的测定
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GB 5009.241-2017
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标准编号: 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: 8,812
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: 食品安全国家标准 食品中镁的测定
GB 5009.241-2017 英文名称: Food safety national standard -- Determination of magnesium in food
中华人民共和国国家标准
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
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
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。
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 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。
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。
第三法 电感耦合等离子体质谱法
GB 5009.241-2017
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
National Food Safety Standard -
Determination of Magnesium in Food
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.
3. No action is required - Full-copy of this standard will be automatically &
immediately delivered to your EMAIL address in 0~60 minutes.
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 Reagents preparation
3.2.1 Nitric acid solution (5+95). take 50mL of nitric acid; pour into 950mL of water;
mix evenly.
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
reagents.
5.2.3 Pressure tank digestion
Take 0.2g~1g (accurate to 0.001g) of solid specimen or accurately pipette
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
volumetric flask; and use water to make constant volume to the scale, mix evenly for
spare-use. Meanwhile do the blank test.
5.2.4 Dry ashing
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
550°C till specimen becomes lime-shape. After cooling off in the muffle furnace, take
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
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.
5.3.2 Drawing of standard curve
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