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GB 14883.8-2016: National Food Safety Standard -- Determination of radioactive substances plutonium - 239 and plutonium - 240 in foods
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National Food Safety Standard -- Determination of radioactive substances plutonium - 239 and plutonium - 240 in foods
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GB 14883.8-2016
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| GB 14883.8-1994 | English | 319 |
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Examination of radioactive materials for foods. Determination of plutonium-239, plutonium-240
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GB 14883.8-1994
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PDF similar to GB 14883.8-2016
Basic data | Standard ID | GB 14883.8-2016 (GB14883.8-2016) | | Description (Translated English) | National Food Safety Standard -- Determination of radioactive substances plutonium - 239 and plutonium - 240 in foods | | Sector / Industry | National Standard | | Classification of Chinese Standard | C53 | | Classification of International Standard | 67.040 | | Word Count Estimation | 11,170 | | Date of Issue | 2016-08-31 | | Date of Implementation | 2017-03-01 | | Older Standard (superseded by this standard) | GB 14883.8-1994 | | Regulation (derived from) | Announcement of the State Administration of Public Health and Family Planning 2016 No.11 |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 14883.8-2016: National Food Safety Standard -- Determination of radioactive substances plutonium - 239 and plutonium - 240 in foods
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(Food safety national standard - Determination of radioactive materials plutonium - 239 and plutonium - 240 in food)
National Standards of People's Republic of China
National Food Safety Standard
Determination of radioactive materials plutonium-239, plutonium - 240
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 14883.8-1994 "Food Examination of radioactive materials plutonium-239, plutonium -240 determination."
This standard compared with GB 14883.8-1994, the main changes are as follows.
--- Standard name was changed to "national food safety standards in food radioactive plutonium-239, plutonium -240 determination";
--- National food safety standards in accordance with the format of the text has been adjusted;
--- Sort out and changed the order of some of the terms and formulas;
--- Added "low background α spectrometer ready" requirement;
--- The second method to TOA to replace the original standard methods N235.
National Food Safety Standard
Determination of radioactive materials plutonium-239, plutonium - 240
1 Scope
This standard applies to the determination of various foods plutonium -239 (239Pu) and plutonium -240 (240Pu) of the total radioactivity concentration.
The first ion exchange method
Principle 2
Nitric acid and hydrogen peroxide leach food ash, 7mol/L ~ 8mol/L nitric acid medium to [Pu (NO3) 6] 2- form (Pu4) set
The amount adsorbed on the anion exchange resin with different concentrations of hydrochloric acid and nitric acid leaching solution to remove the common α emitters and common cation impurities,
With 0.36mol/L hydrochloric acid -0.01 mol/L mixture of hydrofluoric acid desorption, electrodeposition legal source, measured on a low background α spectrometer
239Pu (5.157MeV) and 240Pu (5.168MeV) total concentration (hereinafter referred to as 239 240Pu).
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 hydrochloric acid (HCl).
3.1.2 hydrofluoric acid (HF).
3.1.3 nitric acid (HNO3).
3.1.4 Ammonium nitrate (NH4NO3).
3.1.5 hydroxylamine hydrochloride (NH2OH · HCl).
3.1.6 Sodium nitrite (NaNO2).
3.1.7 sodium hydroxide (NaOH).
3.1.8 Hydrogen peroxide (H2O2).
3.2 reagent preparation
3.2.1 hydrochloric acid - a mixture of hydrofluoric acid. hydrochloric acid solution will 180mL1mol L/poured into 500mL volumetric flask, add 20mL0.26mol/L
Hydrofluoric acid solution and diluted with water to the mark.
3.2.2 hydrochloric acid - a mixture of nitric acid. hydrochloric acid was poured into 500mL to 333mL volumetric flask, add 9.4mL nitric acid and diluted with water to the mark.
3.2.3 Ammonium nitrate - nitric acid mixture. 5 by volume 0.1mol/L solution of nitric acid and three volumes of 0.4mol/L ammonium nitrate solution mixed.
3.2.4 nitric acid solution. 1mol/L, 3mol/L, 7mol/L, 7.5mol/L and 10mol/L.
3.2.5 sodium hydroxide solution. 6mol/L.
3.2.6 2mol/L hydroxylamine hydrochloride solution. Weigh 139g of hydroxylamine hydrochloride, dissolved in an appropriate amount of water, diluted with water to 1L.
3.2.7 2mol/L sodium nitrite solution. Weigh 138g of sodium nitrite, dissolved in an appropriate amount of water, diluted with water to 1L.
3.2.8 251 × 8 trimethylamine polystyrene strong base anion exchange resin. 180μm ~ 250μm. The appropriate amount of resin is poured into 1L burn
Cup, soaked in water for 24h, decanted upper layer of water. Poured into 10% sodium hydroxide solution, and the solution above the resin of about 2cm, stirring occasionally. About 2h
After the liquid was decanted, washed once. After washing the decanted solution was poured into 1mol L hydrochloric acid solution/the solution above the resin of about 2cm, stirring occasionally.
2h after the acid was decanted, washed repeatedly with water until no chlorine ions in solution, dried spare.
Recycled resin. first with 10mL of hydrochloric acid - hydrofluoric acid mixed solution (3.2.1) with 1mL/min flow rate through the column, and then 20mL
7.5mol/L nitric acid through the column at the same flow rate, the standby.
3.3 Standard
239Pu standard solution. radioactive intensity of about 10 decays/(min · mL) magnitude, 0.5mol/L nitrate system.
4 instruments and equipment
4.1 Low background α spectrometer.
a) shall not be less than the diameter of the probe-plated stainless steel sheet (4.8) the diameter of the active region;
b) α spectrometer energies greater than 3MeV integral background count should not exceed 1/h, in the corresponding channel address 239Pu points should not exceed background
0.2 count/h;
c) energy source in 5MeV thin electrodeposited standard resolution should be better than 0.5%, with a plurality of non-linear check reference sources should be less than α
1%, 239Pu measuring efficiency characteristics Road area should not be less than 20%;
d) α spectrometer continuously good stability, 24h drift should be less than 1%.
4.2 muffle furnace.
4.3 centrifuge. speed 3000r/min, the volume of 50mL centrifuge tube or 100mL.
4.4 ion exchange column. See Appendix A.
4.5 electrodeposition tank. See Appendix A.
4.6 magnetic stirrer.
4.7 DC power supply.
4.8-plated stainless steel sheet. steel type 1Cr18Ni9Ti, φ12mm ~ 15mm, thickness of 0.3mm ~ 0.5mm, cloth polishing wheel. Go through before use
Pink scrub dirt, washed with acetone, water rinse after use.
4.9 239Pu standard point source. the rule of law were prepared by electrodeposition, radio-calibrated metering transfer department. Diameter should be the active region of the sample standard source
The same source.
Step 5 Analysis
5.1 low background α spectrometer preparations
May refer to GB/T 16141 Recommended methods spectrometer working state selection, scale and energy efficiency calibration before measuring samples should
The instrument background measurement.
5.2 Preparation of sample and assay
5.2.1 Sampling and pretreatment according to the provisions of GB 14883.1.
5.2.2 Weigh 5g ~ 10g (accurate to 0.001g) ash sample dissolved in 100mL porcelain evaporating dish, add 3mL ~ 5mL10mol/L nitrate
Fluid wetted surface covered dish, on a hot plate heated slowly added dropwise 1mL of hydrogen peroxide, evaporated to near dryness. Coolish after adding 1mL ~
2mL10mol/L solution of nitric acid and hydrogen peroxide 1mL, heated and evaporated to dryness. This repeated process several times until white or gray ash
white.
5.2.3 to ash added 25mL7mol/L nitric acid solution, heated to dissolve the soluble fraction then slowly heated 10min, after cooling switch
Transferred to a centrifuge tube and centrifuged 5min at 3000r/min. With 25mL7mol/L solution of nitric acid leaching is repeated once by centrifugation. Then
25mL hot 7mol/L nitric acid solution was washed raw evaporating dish and the residue was centrifuged, all supernatant was combined, insolubles were discarded.
5.2.4 plus 0.4mL2mol/L hydroxylamine hydrochloride solution into the clear liquid, placing added 0.4mL2mol/L sodium nitrite solution after 10min.
After standing 10min, the solution was heated to 50 ℃, added 1.5g been handled well anion exchange resin (3.2.8), stir on the magnetic stirrer
Mix 30min.
5.2.5 The solution was charged together with ion exchange resin columns (4.4), the flow rate of 1 drop/s ~ 2 drops/s through. Followed by 20mL
Hydrochloric acid - nitric acid mixed solution (3.2.2), 25mL7mol/L nitric acid solution, 3mL3mol/L nitric acid solution, 1mL1mol/L nitric acid solution
Column leaching rate of 1 drop/2s, discarded all the leachates.
5.2.6 The 10mL hydrochloric acid - hydrofluoric acid mixture (3.2.1) heated to about 50 ℃, 2 drops/min ~ 3 drops a flow rate of desorption of plutonium/min.,
Originally collected effluent 7mL desorption solution.
5.2.7 desorption solution evaporated slowly to prevent splashing the samples, so as not to reduce the recovery. With 1mL1mol/L nitric acid solution to dissolve the dry matter, the
Solution was transferred to the electrodeposition bath. 7mL with ammonium nitrate - nitric acid, (3.2.3) the container was washed 3 times, combined eluate into the electrodeposition bath.
5.2.8 at a voltage of 24V, 350mA current conditions electrodeposition 2h, before terminating added 1mL6mol/L hydroxide 1min when
Sodium. Remove the stainless steel sheet, water rinse, dry 239 240Pu measuring radioactivity in the low background α spectrometer.
5.2.9 After measuring the sample surface immediately with 239Pu source counting efficiency standards, reagent blanks and instrument background measurement.
5.3 Determination of radiochemical recovery
Accurately weighed sample and sample measurement and other quality ash added 1.00mL239Pu standard solution (236Pu or 242Pu standard solution acceptable)
5.2.2 ~ 5.2.8 by the same operating procedures, after the measurement according to equation (1) calculate the radiochemical recovery.
R =
N'-N
EA0
(1)
Where.
R --- 239Pu radiochemical recovery;
N '--- radiochemical recovery measured in the corresponding channel region 239Pu net count rate measured in units of counts per minute (cpm);
N --- sample source 239Pu corresponding channel region of the net count rate measured in units of counts per minute (cpm);
E --- α spectrometer detection efficiency of 239Pu standard surface sources;
A0 --- radiochemical recovery added 239Pu amount measured in units of decays per minute (dpm).
5.4 Determination of the reagent blank value
Measure 200mL7mol/L nitric acid solution, according to 5.2.4 - 5.2.8 operating prepare a measurement sample reagent blank value in the sample after measurement
Measurements.
6 expression analysis
Food samples 239 240Pu radioactivity concentration according to equation (2).
A =
NM
60ERW
(2)
Where.
A --- food samples in 239 240Pu radioactivity concentration in units of becquerels per kilogram (Bq/kg);
N --- sample source 239Pu corresponding channel region of the net count rate measured in units of counts per minute (cpm);
M --- fresh ash sample, in units of grams per kilogram (g/kg);
E --- α spectrometer detection efficiency of 239Pu standard surface sources;
R --- 239Pu radiochemical recovery;
W --- ash sample quality analysis, in grams (g).
7 Other
Under typical conditions, the detection limit of the method was 7.2 × 10-4Bq/g ash.
The second extraction chromatography method
Principle 8
Food ash leaching with hydrochloric acid, nitro, in 8mol/L HNO3 medium plutonium [Pu (NO3) 6] 2- form (Pu4) quantitatively adsorbed tri
TOA - polychlorotrifluoroethylene chromatographic column. After removing impurities by washing with 0.4mol/L oxalic acid -2mol/L eluting with a mixture of plutonium nitrate, electrodeposition
Plot legal source, measuring the total concentration of 239Pu and 240Pu in the low background α spectrometer (hereinafter referred to as 239 240Pu).
9 Reagents and materials
Unless otherwise indicated, the methods used were of analytical grade reagents and water as a water GB/T 6682 regulations.
9.1 Reagents
9.1.1 TOA extraction agent. Industrial pure. Before use purified by distillation under reduced pressure, mixed in equal volumes and xylene.
9.1.2 polychlorotrifluoroethylene (Kel-F). 150μm ~ 180μm.
9.1.3 nitric acid (HNO3).
9.1.4 Ammonia (NH4 · H2O).
9.1.5 oxalic acid (H2C2O4).
9.1.6 hydrochloric acid (HCl).
9.1.7 acetone (CH3COCH3).
9.1.8 Ethanol (C2H6O).
9.2 reagent preparation
9.2.1 8mol/L nitric acid solution. 65% 552mL amount of nitric acid, diluted to 1L.
9.2.2 oxalic acid - nitric acid, (A). concentrations of nitric acid and oxalic acid, respectively 0.4mol/L and 2mol/L.
9.2.3 oxalic acid - nitric acid mixed solution (B). concentrations of nitric acid and oxalic acid were 0.05mol/L and 0.3mol/L.
9.2.4 2mol/L sodium nitrite solution. Weigh 138g of sodium nitrite, dissolved in an appropriate amount of water, diluted with water to 1L.
9.2.5 10mol/L hydrochloric acid solution. Measure 833mL of hydrochloric acid, diluted to 1L.
9.2.6 nitro hydrochloric acid. one volume of hydrochloric acid and nitric acid is mixed with 3 volumes, also known as aqua regia.
9.3 Standard
239Pu standard solution. Same as 3.3.
10 instruments and equipment
10.1 Low background α spectrometer. with 4.1.
10.2 muffle furnace.
10.3 Centrifuge. Same as 4.3.
10.4 extraction chromatographic column. See Appendix A. Column packing method. Weigh 1.2g polychlorotrifluoroethylene dried small beaker, was added dropwise with stirring
1.2mL50% tri-n-octylamine - xylene solution, mix well, infrared lamp heating to evaporate the solvent. Cooling water into a slurry, the
Wet mount color layer column. With 8mol/L solution of nitric acid balance standby.
10.5 electrodeposition tank. with 4.5.
10.6 plated stainless steel sheet. Same as 4.8.
10.7 239Pu standard point source. the same 4.9.
11 analysis steps
11.1 low background α spectrometer preparations
With 5.1.
11.2 Sample preparation and assay
11.2.1 Sampling and pretreatment according to the provisions of GB 14883.1.
11.2.2 Weigh 1g ~ 2g (accurate to 0.001g) in 35mL sample gray porcelain evaporating dish with a small amount of hydrochloric acid nitro soaked, steamed slowly heating
To date no mist, and then burned in a muffle furnace 450 ℃ 0.5h. Ignition temperature not exceeding 500 ℃, in order to avoid the formation of insoluble plutonium oxide.
11.2.3 After cooling in ml 8mol/L nitric acid solution was heated leaching filtered residue was washed 2 times with the same solution of nitric acid, 1mL/Ci ~
2mL/times. The combined filtrate 25mL centrifuge tube.
11.2.4 take leaching solution was added a few drops of 2mol/L sodium nitrite solution, heated to regulate and stabilize the positive tetravalent plutonium in a water bath. Rush to make two
Oxide after cooling.
11.2.5 leach solution at a flow rate of 0.3mL/min ~ 0.5mL/min through a chromatographic column (10.4). Then successively with the same flow rate
10mL8mol/L nitric acid solution and 15mL10mol/L hydrochloric acid solution was washed chromatographic column, discard the effluent.
11.2.6 with 10mL oxalic acid - a mixture of nitric acid (A) (9.2.2) eluting plutonium flow rate above. Effluent collected 35mL porcelain evaporating dish.
11.2.7 eluent evaporated low heat until all the oxalic acid decomposition of volatile power deposition.
11.2.8 with 8mL oxalic acid - nitric acid mixture (B) (9.2.3) Fractional the dry matter immersion, equipped transferred into the treated stainless steel sheet
Electrodeposition tank (10.5), add 2 drops of ammonia, the full mix.
11.2.9 platinum wire as the anode, a stainless steel sheet as a cathode power. Electrodeposition at a voltage of 24V, 400mA current conditions
2h.
11.2.10 before the end of plating, concentrated ammonia is added 1mL, continue electrodeposition 1min. Disconnect the power, discard the electrolyte, washed with water electrolyzer.
After removing the stainless steel sheet, followed by acetone, ethanol, washed with water, dried under an infrared lamp, electric stove burning 3min ~ 5min, cooled in a low background α
Measured on the spectrometer.
11.2.11 After the sample measurement surface immediately with 239Pu source counting efficiency standards, reagent blanks and instrument background measurement.
11.3 Determination of radiochemical recovery
Accurately weighed sample and sample measurement and other quality ash added 1.00mL239Pu standard solution (236Pu or 242Pu standard solution acceptable)
11.2.2 - 11.2.10 by the same operating procedures, after the measurement according to equation (1) calculate the radiochemical recovery.
11.4 Determination of the reagent blank value
Measure 200mL7mol/L nitric acid solution, according to 11.2.4 - 11.2.10 operation to prepare a measurement sample reagent blank value in the sample survey
After the measurement volume.
12 analysis results presentation
Food samples 239 240Pu radioactivity concentration calculations with Chapter 6.
Other 13
Under typical conditions, the detection limit of the method was 7.2 × 10-4Bq/g ash.
The third method α radioactivity measurement
Principle 14
With the first method or the second method, only after the power source deposition method, measuring α radioactivity plutonium in the low background α meter, it will
Interference of 238Pu.
15 Reagents and materials
Select the first ion exchange method in Chapter 3 or the second extraction chromatography method Chapter 9.
16 instruments and equipment
16.1 Low Background α radiation measuring instrument.
a) probe diameter should not be less than the diameter of the active region-plated stainless steel sheet;
b) a standard point source of 239Pu measuring the efficiency of not less than 20%;
c) continuously measuring the efficiency of good stability, volatility is not more than 1%;
d) The instrument should be no greater than 1.0 at the end counts/h.
16.2 In addition to a low background α meter instead of the low background α spectrometer, other instruments and equipment to select the first ion exchange method or Chapter 4
Chapter 10 of the second extraction chromatography method.
17 analysis steps
Except after electrodeposition with low background α radioactivity meter instead of the low background α spectrometer measurements, the other with a first ion exchange method
(5.2 to 5.4) or the second extraction chromatography method (11.2 - 11.4). The (1) E where the formula is low background α radioactivity meter mark on 239Pu
Detection efficiency reference plane source.
18 analysis results presentation
Food samples 239 240Pu radioactivity concentration calculations with Chapter 6, in (2) E In this case the formula is low background α radiation measuring instrument
239Pu standard for point source detection efficiency.
Other 19
Under typical conditions, the detection limit of the method was 3.6 × 10-3Bq/g ash.
Appendix A
Extraction chromatographic columns, ion exchange columns and electrodeposition tank
A.1 extraction chromatographic column and ion exchange column
Glass firing, Figure A.1. Extraction chromatographic column and ion exchange column smaller inner diameter of 8mm and 6mm section respectively.
Millimeters
Explanation.
1 --- glass column;
2 --- TOA - polytrifluoroethylene particle or ion exchange resins;
3 --- piston.
Figure A.1 extraction chromatographic column and ion exchange column
A.2 electrodeposition tank
Made of plexiglass, see Figure A.2.
Millimeters
Explanation.
1 --- stainless steel base;
2 --- stainless steel cathode sheet;
3 --- plexiglass tank;
4 --- T platinum rod (φ2);
5 --- cover;
6 --- vent.
Figure A.2 electrodeposition tank
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