GB 8921-1988 Hygienic standard for the limit of radioactive radium-226 in phosphate fertilizers
Some standard content:
National Standard of the People's Republic of China
Limit standard of radioactive radium-226 in phosphate fertilizer
1 Subject content and scope of application
UDC 614.7 : 631 bZxz.net
GB 8921—88
1. This standard is formulated to limit the radioactive contamination of crops and food caused by the application of phosphate fertilizers to a level that is particularly harmful to the human body and to ensure the health and safety of the public and their offspring. 1.2 This standard is formulated in accordance with GB4792.
1.3 This standard applies to phosphate fertilizers for food (including phosphate fertilizers) and phosphate ore (including phosphate concentrate) used to produce phosphate fertilizers. 1.4 This standard shall be implemented under the supervision of the local radiation health protection departments: 2 Reference standards
GB 4792 Basic standards for radiation health protection GE1869 Methods for sampling and preparing analytical samples of phosphate concentrate and phosphate rock [IG 1-392 Ordinary superphosphate
3 Limit standards for 226Ra (hereinafter referred to as Ra) in phosphate fertilizers and phosphate rocks 3.1 The content of 226Ra in phosphate fertilizers shall not exceed 500 q·kg-1. Note:) If the natural content of 226Ra in phosphate fertilizers is less than 30 μm, it complies with this standard. No further determination of 226Ra is required. 3.2 In order to ensure that the content of 226Ra in phosphate fertilizers complies with the limit standards of Article 3.1, the content of 226Ra in phosphate rock used for producing phosphate fertilizers shall not exceed 500 μg·kg-1.
4 Test methods
4.1 The sampling and preparation of phosphate rock samples shall be carried out in accordance with GB 1869. The sampling and preparation of phosphate fertilizer samples shall be carried out according to the method of HG1-392.
4.2 The analysis method of natural potassium in phosphate fertilizer and phosphate rock shall be carried out according to the method in Appendix A of this standard. 4.3 The determination method of 2 in phosphate fertilizer and phosphate rock shall be carried out according to the method in Appendix B of this standard. Approved by the Ministry of Health of the People's Republic of China on February 29, 1988 and implemented on November 1, 1988
A 1 Summary of the method
GB 8921-8
Appendix A
Analysis method of natural potassium
TOPO extraction Br-PADAP spectrophotometry
(Supplement)
After the sample is dissolved. In the presence of sodium fluoride in a mineral acid (1· 4) medium, extract with TOP-cyclopentane, then react with a mixed reagent, color with Br-PADAP, measure the photometric value at a wavelength of 572°, and use the working line to check the result.
A 2 Required reagents
A 2.1 Nitric acid (1+7), chemically pure,
A 2.2 Sodium hydroxide, analytically pure.
A 2.8 Cyclopentane.
A.2. Hydrogen peroxide, chemically pure.
A 2.6 Perchloric acid, analytically pure.
A 2.8 Sodium carbonate (5%).
A 2.7 Sodium hydroxide (20%),
A 2.a Salt (1+11), chemically pure.
A 2.9 Anhydrous ethanol
4 2.10 Aqueous solution of triethanolammonium (20%), with ethanol and pH 7 ~ 8.A 2.11 Mixed ammonium; take solid ammonium nitride, ammonium alkali, ammonium chloride, ammonium nitrate, and mix them in a weight ratio of 3: 0.5: 1: 1. A2.12 TOPO solution (3%) Weigh 30g trioctyl oxide (abbreviated as TOPO), dissolve it in cyclohexane and dilute to 1000ml. (TOPO reagent can be replaced by an alkane carrier called TRPO.) A2.13 BF-PADA reagent (0.05): Take 0.5g 2-(5-bromo-2-pyridinium)-5-ethylamino pyridine (abbreviated as Br-PADAP), dissolve it in ethanol and dilute to 1000ml. A 2.14 Mixed complexing agent Weigh 5 g of cyclohexanediol tetraacetic acid and 5 g of sodium amide in 300 ml of water, dissolve with sodium hydroxide (20%), neutralize with acid (1+11) to pH 7-8, and dilute with water to 1000 mL. A 2.15 and standard quenching solution (5 μg/mL): Accurately weigh 1.1.793 g of tris(III) oxide (spectrally pure), dissolve with hydrochloric acid and peroxide, transfer to a 100 mL container, dilute to the scale with distilled water, take 5 mL of the above solution and put it in a 1HL bottle, dilute to the scale with distilled water. A s Instruments
A a.1 Spectrophotometer,
A 1.2 Acidity meter.
A 9.9. General laboratory instruments and equipment. A. Analysis steps
A4.1 Sample collection: Take 1.000g of sample into a 100mL beaker, add 10 times the amount of mixed ammonium salts of the sample, heat and dissolve on a hot plate until the smoke is gone, remove and cool slightly, add 2~3mL perchloric acid, continue to heat until the smoke is gone, add 10mL nitric acid (1+7) after cooling slightly, heat and extract, filter with a 60mL separatory funnel, wash the beaker and funnel with nitric acid (1+7) three times, and control the solution volume to about 30mL.
GB 8921—B8
A 4.2 Extraction: Add 1mL sodium oxide (3%) and 5mL TOPU liquid (3%), extract for 1 min, discard the aqueous phase after phase separation, wash the organic phase once with 5mL nitric acid (1+7), and fill the aqueous phase. A 4.8 Back-lift: Add 5mL 1. Mix the complexing agent solution, incubate for 1 min, and after separation, transfer the aqueous phase to 12.5 mL of A4.4 colorimetric tube. Add 1 drop of 1% ammonium hydroxide (1 + 1) to the colorimetric tube, and adjust the color to red. Then add hydrochloric acid (1 + 1) to make it colorless. Add 1 mL of ammonium hydroxide (20%), 3.5 mL of acetone, and 1 mL of Br-PADAP solution (0.05%). Dilute with water to the scale. Use a 3 cm absorption cell at 572 nm on the spectrophotometer, use the reagent blank as a reference, measure its absorbance, and find the uranium content on the working curve. Prepare the curve. Take 0, 5.0, 20.0, 15.0, 20.0, 25.0, 30.0, and 35.0 μg of platinum standard solution and place them in 60 mL of a separating funnel. Perform the following operations according to A4.2 to A4.5. 4.4 Steps are followed. Draw the working oil line. A 5 Calculate the sample content C. (ppm) by the following formula:
- the chain content found from the working curve; where A -
- the sample weight, K.
AB Precision
The difference between the results of two parallel determinations should not exceed 10. Appendix
* Determination of Ra
Scintillation radiant gas method
(Supplementary)
B1 Summary of the method
The sample is melted, leached in water, filtered, activated, dissolved in hydrochloric acid, or a transparent micro-solution is prepared, sealed and adjusted, the accumulated :22R is transferred into a scintillation chamber, the α value is determined, and the value of !2Ra is calculated. B 2 Reagents
B 2.1 Anhydrous sodium carbonate, analytical grade,
B 2.2 Sodium peroxide, analytical grade.
B 2. Sodium nitrate (0.1N), analytical grade. B 2.4 Hydrochloric acid (1 +3) analytical grade
B 2.5 Citric acid, desigma-grade,
B 2.6 22R Ra standard solution [.0. 04 ~0.1Bq). B Instruments and equipment
B 3.1 Automatic calibrator
B 3.2 Indoor hydrogen, needle analyzer.
B 3.3 Spherical scintillation tank (500 mL).
Ba.4 Crucible (50 InL),
B.5 Expander (100 mL).
B 3.6 Vacuum pump (30 L/min).
B 3.7 Box repulsion meter.
B4 Test steps
GB 6921-8B
B4.1 Melt sample Accurately weigh 1g of the sample and put it in a nickel-plated crucible. Add 2~4g of anhydrous sodium carbonate and 6g of sodium peroxide. After stirring, cover it with a layer of about 3g of sodium peroxide. Put the sample in a muffle furnace at 65~700℃ and melt for 7~10min. When the melt turns into a red fluid, take it out and cool it down slightly.
B.2 Extraction Put the outer wall of the crucible in cold water to "shell off", then put it in a 500mL flask. Use 200mL of hot distilled water to extract. After the violent reaction stops, wash the vortex with a little dilute acid. Also use distilled water to rinse the extract and wheat flour. Add 3L of sodium nitrate solution (0.1%), heat to near boiling, and take it out. B4.3 Separation: Filter the above liquid on the qualitative line, precipitate it with sodium carbonate solution (1) 3 times, wash it with distilled water once, and remove the filtrate.
B4.4. Dissolve the sample with a mixture of salt (1-3) and citric acid in a 50mL beaker, transfer the solution into a 100mL diffuser, wash the filter paper with hot distilled water until it turns yellow, and store the washing solution in the diffuser. The total amount of solution is controlled at about 35mL, and the exhaust is used. Seal for 1 week and record the seal. B4.5 Gas supply. Draw the vacuum chamber, the drying tube, the diffuser covered with the sample solution, the activated carbon tube and the bubbling tube as shown in Figure B1. When supplying gas, first open the flash chamber and the diffuser, then slowly open the glass switch of the activated carbon tube, control the air flow rate to about 120 bubbles per minute, and the gas supply speed can be accelerated for 10 minutes. The gas supply time is controlled at about 15 minutes. B1 Gas supply system connection diagram
1, 2, 3,
small water and fire; 1 is the gas supply system:
5, a gas is separated and closed: 6-+ drying tube, 8-flash chamber B4.6 After the gas supply is completed, the scintillation chamber is placed for 3 hours, and the measurement is performed 3 times under the selected working conditions, and each measurement is 10 minutes. B4.7 After the exhaust is completed, the vacuum pump is used to remove the gas and its gas in the scintillation chamber, so that the scintillation chamber returns to the positive background. R4.8 K provincial calibration Replace the diffuser with the diffuser filled with 36Ra standard washing solution, and operate according to the steps of B1.5 to B4.7.
B5 Calculation
GB 8921
B5.1 K value meter The K value (Bn/cP) of the flickering screen is calculated as follows: ARu standard (1-e-At)
Formula: Aa standard
Diffuser towel 226 The decay constant of the active part of Ra standard solution, Bq, is: 1, the cumulative time of
, d, the net counting rate of 2Ra standard solution measured by
, cpm, B5.2 Calculation of the content of 226Ra in sample The content of 226Ra in sample CR (Bq·kg-1) is calculated as follows: K.1
Ch--W.cr-ealy
Where: 1
Net counting rate of the sample being tested, pm;
Weight of the sample being tested, kg;
Decomposition constant of monochlorine, d-\,
--Integral time of oxygen, d.
B 6 Precision
Limit The difference between the results of two half-measurements shall not exceed 20%. Appendix C
Implementation of the Standard
(Supplementary)
C1 The natural content of phosphate fertilizer and phosphate rock shall be self-inspected by the quality inspection department of the manufacturer according to the method specified in Article 4.2. The daily inspection samples shall be prepared separately. The self-inspection results and the white test samples shall be sent to the local radiation health protection department in a timely manner. If the national white test is not complete, the local radiation health protection department shall be entrusted to conduct inspection.
C2 If the inspection result of the natural platinum content of the product is less than 30 Ppm, it is considered that the product meets the requirements of Chapter 3 of the technical standard, and no 226Ra measurement is required. If the natural content exceeds 30 Ppm, the sample shall be sent to the local radiation health protection department for 226Ra measurement according to the method specified in Article 4.8.
C9 If the inspection shows that the 226Ra content does not meet the requirements of Chapter 3 of the standard, the sample shall be re-taken for re-inspection according to the method specified in Chapter 4. C. If the re-test results still do not meet the requirements of Section 3 of this standard, the entire batch of phosphate fertilizers cannot be shipped or used, and the phosphate products shall be processed according to C5 or no phosphate fertilizer shall be produced.
C5 When phosphate ore with a 226Ra concentration exceeding 500 Bg·kg- is used to produce phosphate fertilizers, it shall be approved by the relevant radiation health department and undergo testing to ensure that the fertilizer produced meets the requirements of Section 3 of this standard. C6 The operating and using units have the right to test the purchased products in accordance with the test methods specified in this standard to check whether they meet the key points of this standard. C7 When a new or abandoned phosphate mine is built, a quality report with 26Ra content shall be submitted to the local radiation health department. It may be put into production after being re-tested to meet this standard.
GHa92r88
Additional Notes:
The standard was proposed by the Health and Epidemic Prevention Department of the Ministry of Health, and the National Health Standards Technical Committee was reviewed and approved by the Health Protection Standards Subcommittee. This standard is under the responsibility of the Hunan Provincial Institute of Occupational Disease Prevention and Control, and the Ministry of Health entrusted the technical support! 1 The first Ministry of Health 1 Industry Health Laboratory is responsible for the interpretation group. 156
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