GB 5009.241-2017 English PDF (GB5009.241-2017)

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GB 5009.241-2017: National food safety standard - Determination of Magnesium in Food
GB 5009.241-2017
Food safety national standard - Determination of magnesium in food
National Standards of People's Republic of China
National standards for food safety
Determination of magnesium in food
2017-04-06 release
2017-10-06 implementation
National Health and Family Planning Commission of the People 's Republic of China
State Food and Drug Administration issued
Preface
This standard replaces GB/T 5009.90-2003 "Determination of iron, magnesium and manganese in food", GB/T 9695.21-2008 "Meat and meat products
Determination of magnesium content ", GB 5413.21-2010" Food safety national standard infant food and dairy products in calcium, iron, zinc, sodium, potassium, magnesium, copper and
Determination of manganese, GB/T 23375-2009 "Determination of copper, iron, zinc, calcium, magnesium and phosphorus in vegetables and their products", GB/T 14609-2008 "
Determination of copper, iron, manganese, zinc, calcium and magnesium in cereals and their products - Flame atomic absorption spectrometric method, GB/T 18932.12-2002
Determination of potassium, sodium, calcium, magnesium, zinc, iron, copper, manganese, chromium, lead and cadmium in honey atomic absorption spectrometry, NY82.19-1988
Method for determination of magnesium in determination of calcium and magnesium in fruit juice determination method.
This standard compared with GB/T 5009.90-2003, the main changes are as follows.
--- standard name changed to "food safety national standard food magnesium determination";
The sample pretreatment method is adjusted to wet digestion, microwave digestion, dry ashing and pressure tank digestion;
- Determination of sample retention Flame atomic absorption spectrometry, removal of titration;
Increase the inductively coupled plasma emission spectroscopy for the second method;
Increased inductively coupled plasma mass spectrometry for the third method.
National standards for food safety
Determination of magnesium in food
1 Scope
This standard specifies the determination of magnesium content in food by flame atomic absorption spectrometry, inductively coupled plasma emission spectroscopy and inductance
Combined with mass spectrometry.
This standard applies to the determination of magnesium content in various foods.
Flame Atomic Absorption Spectrometry
2 principle
After the sample was digested, the absorbance was measured at 285.2 nm by flame atomization. The absorbance of magnesium is within a certain concentration range
Magnesium content is proportional to, compared with the standard series quantitative.
3 reagents and materials
Unless otherwise stated, the reagents used in this method are of grade I, and water is a secondary water specified in GB/T 6682.
3.1 Reagents
3.1.1 nitric acid (HNO3).
3.1.2 perchloric acid (HClO4).
3.1.3 hydrochloric acid (HCl).
3.2 reagent preparation
3.2.1 nitric acid solution (5 95). measure 50mL nitric acid, pour into 950mL water, mix.
3.2.2 nitric acid solution (1 1). measure 250mL nitric acid, into 250mL water, mix.
3.2.3 hydrochloric acid solution (1 1). measure 50mL hydrochloric acid, into 50mL of water, mix.
3.3 standards
Metal magnesium (Mg, CAS No. 7439-95-4) or magnesium oxide (MgO, CAS number. 1309-48-4). purity> 99.99%. Or by country
Certified and awarded a standard concentration of magnesium standard solution.
3.4 standard solution preparation
3.4.1 Magnesium standard stock solution (1000mg/L). accurately weighed 0.1g (accurate to 0.0001g) metal magnesium or 0.1658g (accurate to
0.0001g) was calcined at 800 ℃ ± 50 ℃ to constant weight of magnesium oxide, dissolved in 2.5mL hydrochloric acid solution (1 1) and a small amount of water, into the 100mL
Capacity bottle, add water to the mark, mix.
3.4.2 magnesium standard intermediate (10.0mg/L). accurate absorption of magnesium standard stock solution (1000mg/L) 1.00mL, with nitric acid solution (5 95)
Set to 100mL volumetric flask, mix.
3.4.3 magnesium standard series solution. absorb magnesium standard intermediate liquid 0mL, 2.00mL, 4.00mL, 6.00mL, 8.00mL and 10.0mL in
100mL volumetric flask with nitric acid solution (5 95) constant volume to the scale. The mass concentration of the magnesium standard series solution is 0mg/L,
0.200 mg/L, 0.400 mg/L, 0.600 mg/L, 0.800 mg/L and 1.00 mg/L.
Note. According to the sensitivity of the instrument and the actual content of magnesium in the sample to determine the standard series of magnesium concentration in the solution.
4 instruments and equipment
Note. All glassware and polytetrafluoroethylene digestion tanks are required nitric acid solution (1 5) soaked overnight, rinse with tap water, and finally rinse with water.
4.1 Atomic Absorption Spectrometer. Flame Atomizer, Magnesium Hollow Cathode Lamp.
4.2 Analysis of balance. 0.1mg and 1mg.
4.3 Adjustable electric furnace.
4.4 Adjustable heating plate.
4.5 Microwave digestion system. Dispersed tetrafluoroethylene digestion tank.
4.6 constant temperature drying oven.
4.7 pressure digestion tank. with PTFE digestion tank.
4.8 muffle stove.
5 Analysis steps
5.1 Preparation of the sample
Note. Sampling and preparation should avoid sample contamination.
5.1.1 Food, legume samples
After removing the debris from the sample, it is crushed and stored in a plastic bottle.
5.1.2 vegetables, fruits, fish, meat and other samples
Samples were washed with water, dried, edible parts, made of homogenate, stored in plastic bottles.
5.1.3 beverage, wine, vinegar, soy sauce, edible vegetable oil, liquid milk and other liquid samples
Shake the sample.
5.2 Sample digestion
5.2.1 Wet digestion
Weigh the solid sample 0.2g ~ 3g (accurate to 0.001g) or accurately remove the liquid sample 0.500mL ~ 5.00mL in the scale with the digestion
Tube, add 10mL nitric acid, 0.5mL perchloric acid, in the adjustable electric furnace digestion (reference conditions. 120 ℃/0.5h ~ 1h, rose to
180 ℃/2h ~ 4h, rose to.200 ℃ ~ 220 ℃). If the digestive solution was tan, then add nitric acid, digestion to take white smoke, digestion was no
Color transparent or slightly yellow, remove the digestive tube, cooling the water volume to 25mL, mix spare. At the same time do reagent blank test. Also available
With a conical flask, on the adjustable heating plate, according to the above method of operation for wet digestion.
5.2.2 Microwave digestion
Weigh the solid sample 0.2g ~ 0.8g (accurate to 0.001g) or accurately remove the liquid sample 0.500mL ~ 3.00mL in the microwave digestion
Tank, add 5mL nitric acid, according to the microwave digestion steps to digest the sample, digestion conditions can refer to Appendix A. After cooling, remove the digestion
Tank, in the hot plate at 140 ℃ ~ 160 ℃ acid up to 0.5mL ~ 1mL. After dissolution of the tank, the digestive solution was transferred to a capacity of 25 mL
Bottle, with a small amount of water to wash the digestion tank 2 to 3 times, combined with washing liquid in the volumetric flask and water volume to the scale, mix spare. While doing reagents
Blank test.
5.2.3 Pressure tank digestion
Weigh the solid sample 0.2g ~ 1g (accurate to 0.001g) or accurately remove the liquid sample 0.500mL ~ 5.00mL in the digestion tank
, Add 5mL nitric acid. Cover the inner cover, tighten the stainless steel jacket, into the constant temperature drying box, at 140 ℃ ~ 160 ℃ for 4h ~ 5h.
After cooling slowly spin out the outer tank, remove the digestion tank, on the adjustable heating plate at 140 ℃ ~ 160 ℃ acid to about 1mL. cool down
After the digestive solution transferred to the 25mL volumetric flask, with a small amount of water to wash the inner tank and the inner lid 2 to 3 times, combined with washing liquid in the volumetric flask and water
Constant volume to scale, mix spare. At the same time do reagent blank test.
5.2.4 Dry ashing
Weigh the solid sample 0.5g ~ 5g (accurate to 0.001g) or accurately remove the liquid sample 0.500mL ~ 10.0mL in the crucible, will
The crucible is heated slowly on the hot plate, and the micro fire is carbonized to no longer smoke. The carbonized sample was placed in a muffle furnace and aged at 550 ° C for 4 h. If
Ashes in the sample after the black particles, the crucible should be cooled to room temperature and then add a little nitric acid solution (5 95) wetting the residue in the hot plate
After drying, the muffle furnace was dried at 550 ° C until the sample became ashes. After cooling in a muffle furnace, remove it and cool to room temperature with 2.5 mL
Nitric acid solution (1 1) dissolved and washed with a small amount of water crucible 2 to 3 times, combined with washing liquid in the volumetric flask and set to 25mL,
use. At the same time do reagent blank test.
5.3 Determination
5.3.1 Instrument reference conditions
According to their respective instrument performance to the best condition. Reference conditions. air - acetylene flame, wavelength 285.2nm, slit 0.2nm, light power
Flow 5mA ~ 15mA.
5.3.2 Production of standard curve
The magnesium standard series solution according to the mass concentration from low to high order were introduced into the flame atomizer after the measured absorbance value to the quality of concentrated
Degrees for the abscissa, absorbance value for the vertical axis, the production of standard curve.
5.3.3 Determination of sample solution
Under the same experimental conditions as the standard solution, the blank solution and the sample solution were introduced into the atomizer to measure the absorbance value respectively.
Standard series is more quantitative.
6 Analysis of the results of the expression
The content of magnesium in the sample is calculated according to formula (1)
X =
(Ρ - ρ0) × V
(1)
Where.
X - the amount of magnesium in the sample in milligrams per kilogram or milligram per liter (mg/kg or mg/L);
Ρ --- mass concentration of magnesium in the sample solution, in milligrams per liter (mg/L);
Ρ0 --- mass concentration of magnesium in blank solution in milligrams per liter (mg/L);
V - the volume of the digestive solution in milliliters (mL);
M --- sample sample volume or removal volume, in grams or ml (g or mL).
When the magnesium content ≥10.0mg/kg (or mg/L), the calculation results to retain three significant figures, when the magnesium content < 10.0mg/kg (or
Mg/L), the result of the calculation retains two significant digits.
7 precision
The absolute difference between the two independent determinations obtained under repeatability shall not exceed 10% of the arithmetic mean.
8 other
When the sample volume is 1g (or 1mL), the volume of the volume is 25mL, the detection limit is 0.6mg/kg (or 0.6mg/L), quantitative
Limited to 2.0mg/kg (or 2.0mg/L).
The second method of inductively coupled plasma - atomic emission spectrometry
See GB 5009.268.
The third method of inductively coupled plasma mass spectrometry
See GB 5009.268.
Appendix A
Microwave digestion temperature program
The microwave digestion procedure is shown in Table A.1.
Table A.1 Microwave digestion procedure
step
set temperature
Heating time
Min
Constant temperature time
Min