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GB 14883.5-2016: National Food Safety Standard -- Determination of radioactive substance polonium - 210 in foods
Status: Valid GB 14883.5: Evolution and historical versions
| Standard ID | Contents [version] | USD | STEP2 | [PDF] delivered in | Standard Title (Description) | Status | PDF |
| GB 14883.5-2016 | English | 109 |
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National Food Safety Standard -- Determination of radioactive substance polonium - 210 in foods
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GB 14883.5-2016
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| GB 14883.5-1994 | English | 239 |
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Examination of radioactive materials for foods. Determination of polonium-210
| Obsolete |
GB 14883.5-1994
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PDF similar to GB 14883.5-2016
Basic data | Standard ID | GB 14883.5-2016 (GB14883.5-2016) | | Description (Translated English) | National Food Safety Standard -- Determination of radioactive substance polonium - 210 in foods | | Sector / Industry | National Standard | | Classification of Chinese Standard | C53 | | Classification of International Standard | 67.040 | | Word Count Estimation | 5,559 | | Date of Issue | 2016-08-31 | | Date of Implementation | 2017-03-01 | | Older Standard (superseded by this standard) | GB 14883.5-1994 | | Regulation (derived from) | Announcement of the State Administration of Public Health and Family Planning 2016 No.11 | | Issuing agency(ies) | National Health and Family Planning Commission of the People's Republic of China, State Food and Drug Administration | GB 14883.5-2016: National Food Safety Standard -- Determination of radioactive substance polonium - 210 in foods
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(Food safety national standard - Determination of radioactive substance polonium - 210 in food)
National Standards of People's Republic of China
National Food Safety Standard
Determination of radioactive substance polonium-210
Issued on.2016-08-31
2017-03-01 implementation
People's Republic of China
National Health and Family Planning Commission released
Foreword
This standard replaces GB 14883.5-1994 "test radioactive materials for foods - Determination of polonium-210."
This standard compared with GB 14883.5-1994, the main changes are as follows.
--- Standard name was changed to "national food safety standards in food radioactive polonium-210 Determination";
--- National food safety standards in accordance with the format of the text has been adjusted;
--- Sort out and changed the order of some clauses;
--- Fixed a calculation formula of the original standards.
National Food Safety Standard
Determination of radioactive substance polonium-210
1 Scope
This standard applies to all types of foods polonium -210 (210Po) measurement.
Principle 2
Food fresh sample with nitric acid - hydrogen peroxide - perchloric acid wet ashing destroy organic matter, with silver or nickel sheet from sheet deposition separation 210Po, with
α radiometric measurement of α radioactive sample to calculate the concentration of 210Po in food.
3 Reagents and materials
Unless otherwise indicated, the methods used were of analytical grade reagents and water as a water GB/T 6682 regulations.
3.1 Reagents
3.1.1 hydrochloride Hydrazine (N2H4 · 2HCl).
3.1.2 sodium hydroxide (NaOH).
3.1.3 phenolphthalein (C20H14O4).
3.1.4 Ethanol (C2H6O).
3.1.5 nitric acid (HNO3).
3.1.6 hydrochloric acid (HCl).
3.1.7 perchloric acid (HClO4).
3.1.8 ascorbic acid (C6H8O6).
3.1.9 Hydrogen peroxide (H2O2).
3.2 reagent preparation
3.2.1 25% hydrochloric acid diamide solution. Weigh 25g diamide hydrochloride, dissolved in water and diluted to 100mL.
3.2.2 30% sodium hydroxide solution. Weigh 30g sodium hydroxide dissolved in water and diluted to 100mL.
3.2.3 phenolphthalein indicator (1%). Weigh 0.5g of phenolphthalein dissolved 50mL95% ethanol.
3.3 Standard
210Pb-210Po balance 210Po standard solution or standard solution. radioactivity concentration of about 1 × 103 decays/(min · mL).
3.4 Material
Silver sheet or nickel sheet. the thickness of about 0.1mm electrolytic silver sheet (having a thickness of 0.2mm or electrolytic nickel sheet) cut size, shape and scale
The same shape as the quasi supervision source (4.2), in the detergent solution in boiling 10min ~ 20min, washed clean after immersion in water with a spare.
4 instruments and equipment
4.1 Low Background α radiation measuring instrument. probe diameter of not less than 2cm, the background count rate is not more than 1 count/min.
4.2 241Am or 239Pu standards supervisory Source. State legal measures issued by the certified standard plate plating source.
4.3 glass bottle deposit. In the center of the bottom of the bottle 250mL scale plasma drill a hole diameter of 1cm. When the bottom up with the solution and stir
Whereby the rods are into the bottle. Put in the bottle cap 0.4cm of aluminum pad, and then placed a silver piece (or nickel plate), plus 0.3cm thick plastic
washer. Washer inside diameter of 1.8cm, shall be watertight after screwing on the lid. Electrodeposition tank also.
4.4 thermostatic mixing device. in a constant temperature water bath is installed above the porous stirring device consists of a single-phase series motor associated with the drive. Series in tune
Voltage transformer to regulate the speed of rotation of the paddles. Magnetic stirrer versa.
Step 5 Analysis
5.1 Sampling
Sampling conducted by GB 14883.1 requirements.
5.2 Sample preparation
5.2.1 FRESH direct analysis. To prevent corruption in the mining milk, may be added to 5mL of formaldehyde per liter of fresh milk.
5.2.2 Weigh sample 5g ~ 50g (accurate to 0.01g) in 500mL beaker was slowly added 100mL nitric acid, heated on a sand bath. for
Prevent spillage of sample, should be started when a large amount of sand removed from the beaker bubble bath and stirring constantly, if necessary, can be immersed in cold water in a beaker to slow down
The reaction rate, and then heating was continued under stirring, after the disappearance of the foam to the cover with a watch glass, and evaporation was continued when no hydrogen peroxide was added dropwise. According to sample
Product amount and kind of decisions of hydrogen peroxide, generally 10mL ~ 60mL. Prior to cooking sticky and no clear solution, concentrated by evaporation and then continue
Reduced to about 5mL.
5.2.3 For samples containing more fat, such as milk, meat, fish and eggs, when added to a solution of nitric acid was heated on a sand bath foam disappears
The solution obviously divided when oil and water phases, the hot liquid was rapidly poured into a beaker of 250mL separating funnel, standing layer after layer of acid
Into the original beaker, 50mL hot oil phase was washed once with nitric acid, combined acid. Discard the oil phase. Continue in the sand bath of nitric acid and hydrogen peroxide
Cooking sticky and no solution to clear, and then concentrated to 5mL.
5.2.4 added 15mL 5mL nitric acid and perchloric acid, and evaporation was continued on a sand bath. When nitric acid solution was evaporated and warmed to do with anti-perchlorate
Seasonal, most samples will be violent reactions, sometimes rapidly darkening solution. To remove the beaker then press perchlorate handling precautions as soon as possible
operating. Coolish, adding 5mL nitric acid and carefully heated. Samples containing organic matter should be repeated several times more heat treatment in the presence of nitric acid, straight
Until the solution becomes clear. Remove traces of nitric acid, perchloric acid until a large number of white smoke, and evaporation was continued to dryness, the residue is white, cool.
5.3 autodeposition
5.3.1 The residue was dissolved with 30mL water, dropping 3 drops of 1% phenolphthalein indicator, 30% sodium hydroxide solution and the solution becomes reddish immediately available,
Join 2.5mL hydrochloric acid and diluted with water to 60mL, making it 0.5mol/L hydrochloric acid system.
5.3.2 Add approximately 200mg of ascorbic acid and 0.5mL25% hydrochloric acid diamide solution containing silver flake has been transferred (or nickel plate) and verified to be watertight
Deposit bottle at 96 ℃ water bath deposition mechanical stirring 2.5h. After removing pieces of silver (or nickel plate), rinse the surface with a fine flow deposition
After drying at room temperature.
5.4 210Po preparation and detector efficiency standards to determine the source
5.4.1 equipped with a silver sheet or nickel sheet deposition flask, 57.5mL water, 2.5mL hydrochloric acid, the solution becomes 0.5mol/L hydrochloric acid body
system. Imbibe a certain amount of 210Pb-210Po standard solution equilibrium (or 210Po standard solution) is deposited into the bottle, according to the deposition 2h from 5.3 above, it
Deposition efficiency can reach 99%, it can be used as a standard source for 210Po detector efficiency measurements of 210Po.
5.4.2 The standard source in the prepared 210Po low background α radiation measuring instrument measuring instrument detection efficiency 210Po by the formula (1)
Calculated.
ε =
N0
D0
(1)
Where.
ε --- detector efficiency of the 210Po;
Net count rate N0 --- 210Po standard source, in units of counts per minute (cpm);
D0 --- added to a standard source of 210Po radioactivity 210Po, decay units per minute (dpm).
5.5 Determination of the chemical recovery
5.5.1 Analysis of samples with the same amount of sample, a solution containing a known accurate standard solution 210Po activity, according to 5.2.2 - 5.3.2 Step
Operates to determine the chemical recovery.
5.5.2 chemical yield according to equation (2).
R =
N'-N
εD
(2)
Where.
R --- chemical recovery;
N '--- known amount 210Po determination of chemical recovery was measured count rate in units of counts per minute (cpm);
N --- sample count rate in units of counts per minute (cpm);
ε --- detector efficiency of the 210Po;
When added to the sample D --- radioactivity 210Po determination of the chemical recovery unit of decays per minute (dpm).
5.6 radiometric
5.6.1 Place the sample source 5h, in low background α α radiation measuring instrument measuring the radioactivity 210Po.
The active area of the same size as the sample source 239Pu or 241Am source standard 5.6.2 source as supervision before and after each batch of samples for routine analysis
Efficiency correction.
5.6.3 Samples should be measured before and after the end of the measurement.
6 expression analysis
210Po concentration of radioactivity in food by the formula (3) Calculated.
A =
N-Nb
60εRW
(3)
Where.
A --- concentration of radioactivity in food 210Po, in units of becquerels per kilogram (Bq/kg) or becquerels per liter (Bq/L);
N --- sample count rate in units of counts per minute (cpm);
Nb --- background count rate in units of counts per minute (cpm);
ε --- detector efficiency of the 210Po;
R --- chemical recovery;
W --- analysis sample weight in grams (g).
7 Other
Under typical conditions, the detection limit of this method was 0.74Bq/g ash.
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