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This standard replaces the determination of manganese in GB/T 5009.90-2003 Determination of Iron, Magnesium and Manganese in Foods, 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 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 23545-2009 Determination of Manganese in White Wine - Inductively Coupled Plasma Atomic Emission Spectrometry, GB/T 18932.11-2002 Method for Determination of Potassium, Phosphorus, Iron, Calcium, Zinc, Aluminum, Sodium, Magnesium, Boron, Manganese, Copper, Barium, Titanium, Vanadium, Nickel, Cobalt, Chromium Contents in Honey - Inductively Coupled Plasma Atomic Emission Spectrometric Method, GB/T 18932.12-2002 Method for the Determination of Potassium, Sodium, Calcium, Magnesium, Zinc, Iron, Copper, Manganese, Chromium, Lead, Cadmium Contents in Honey - Atomic Absorption Spectrometry and NY/T 1653-2008 Determination for Mineral Elements in Vegetables, Fruits and Derived Products by ICP-AES Method.
The following main changes have been made with respect to above standards:
——The standard name is revised as "National Food Safety Standard - Determination of Manganese in Foods";
——Partial contents of specimen preparation are modified;
——Partial contents of specimen digestion are modified;
——Inductively coupled plasma emission spectrometry is revised as Method II, and inductively coupled plasma mass spectrometry as Method III;
——Method detection limit and quantitation limit are added;
——Annex is added.
National Food Safety Standard
Determination of Manganese in Foods
1 Scope
This standard specifies flame atomic absorption spectrometry, inductively coupled plasma emission spectrometry and inductively coupled plasma mass spectrometry determination methods for manganese in foods.
This standard is applicable to determination of manganese in foods.
Method I Flame Atomic Absorption Spectrometry
2 Principle
After digestion treatment, inject the specimen into atomic absorption spectrometer, and manganese absorbs 279.5nm resonance line after flame atomization; within certain concentration range, its absorption value is in direct proportion to manganese content and is compared with standard series for quantification.
3 Reagents and Materials
Unless otherwise specified, guaranteed reagent and Class-II water (defined in GB/T 6682) are adopted for the purpose of this method.
3.1 Reagents
3.1.1 Nitric acid (HNO3).
3.1.2 Perchloric acid (HClO4).
3.2 Preparation of reagents
3.2.1 Mixed acid [perchloric acid + nitric acid (1+9)]: take 100ml perchloric acid, slowly add into 900mL nitric acid and mix uniformly.
3.2.2 Nitric acid solution (1+99): take 10mL nitric acid, slowly add into 990mL water and mix uniformly.
3.3 Standard product
Manganese metal standard product (Mn): with purity greater than 99.99%.
3.4 Preparation of standard solutions
3.4.1 Manganese standard stock solution (1000mg/L): accurately weigh 1g (accurate to 0.0001g) manganese metal, dissolve with nitric acid and transfer into 1000mL volumetric flask, add nitric acid solution to the scale, mix uniformly, store in polyethylene bottle at 4℃ or use the standard solution approved and awarded with reference material certificate by the State.
3.4.2 Manganese standard working solution (10.0mg/L): accurately pipet 1.0mL manganese standard stock solution into a 100mL volumetric flask, dilute with nitric acid solution to the scale and then store in polyethylene bottle at 4℃.
3.4.3 Manganese standard series working solutions: accurately pipet 0mL, 0.1mL, 1.0mL, 2.0mL, 4.0mL and 8.0mL manganese standard working solution into 100mL volumetric flasks respectively, scale the volume with nitric acid solution to the scale and mix uniformly. In such standard series working solutions, the mass concentrations of manganese are 0mg/L, 0.010mg/L, 0.100mg/L, 0.200mg/L, 0.400mg/L and 0.800mg/L respectively, the concentration range of standard solution may be properly adjusted according to the manganese concentration in actual sample solution.
4 Instruments and Apparatus
4.1 Atomic absorption spectrometer: equipped with flame atomizer and hollow cathode lamp of manganese.
4.2 Analytical balance: with sensibility of 0.1mg and 1.0mg.
4.3 Steel cylinder acetylene gas and air compressor for analysis.
4.4 Sample grinding equipment: homogenizer and high speed grinder.
4.5 Muffle furnace.
4.6 Adjustable temperature control electric hot plate.
4.7 Adjustable temperature control electrothermal furnace.
4.8 Microwave digestion system: equipped with polytetrafluoroethylene digestion inner tank.
4.9 Thermostatic drying oven.
4.10 Pressure digestion tank: equipped with polytetrafluoroethylene digestion inner tank.
5 Analysis Steps
5.1 Preparation of specimen
5.1.1 Solid sample
5.1.1.1 Dry sample
Take the edible parts of the samples with low moisture content, such as bean, grain, fungi, tea, dried fruit and bakery products, and crush them uniformly with high speed grinder if necessary; shake well solid dairy products and powder samples with uniform state such as albumen powder and flour.
5.1.1.2 Fresh sample
Clean the samples with high moisture content, such as vegetables, fruits and aquatic products, dry them in the air if necessary, take the edible parts and homogenize uniformly; as for meat and eggs, take the edible parts and homogenize uniformly.
5.1.1.3 Quick-frozen and canned foods
As for the samples of unfrozen quick-frozen and canned foods, take the edible parts and homogenize uniformly.
5.1.2 Liquid samples
Shake well such samples as soft drink and flavorings.
5.1.3 Semisolid samples
Mix uniformly.
5.2 Digestion of specimen
5.2.1 Microwave digestion method
Weigh 0.2~0.5g (accurate to 0.001g) specimen in a microwave digestion inner tank, heat the samples containing ethanol or carbon dioxide on electric hot plate at low temperature to remove ethanol or carbon dioxide, add 5~10mL nitric acid, cover it and place for 1h or overnight, tighten the outer tank, put into microwave digestion system for digestion (see Table A.1 for the digestion conditions). Take out the inner tank after cooling, put on adjustable temperature control electric hot plate, digest to nearly dry at 120~140℃, scale the volume with water to 25mL or 50mL and mix uniformly for standby. Meanwhile, carry out blank test.
5.2.2 Pressure tank digestion method
Weigh 0.3~1g (accurate to 0.001g) specimen in a polytetrafluoroethylene pressure digestion inner tank, heat the samples containing ethanol or carbon dioxide on electric hot plate at low temperature to remove ethanol or carbon dioxide, add 5mL nitric acid, cover it and place for 1h or overnight, tighten the outer tank, put into thermostatic drying oven for digestion (see Table A.1 for the digestion conditions). Take out the inner tank after cooling, put on adjustable temperature control electric hot plate, digest to nearly dry at 120~140℃, scale the volume with water to 25mL or 50mL and mix uniformly for standby. Meanwhile, carry out blank test.
Foreword i
1 Scope
2 Principle
3 Reagents and Materials
4 Instruments and Apparatus
5 Analysis Steps
6 Expression of Analysis Results
7 Accuracy
8 Other
Annex A Reference Conditions for Digestion of Specimen
