GB 14883.1-2016National food safety standard - General rules for the examination of radioactive substances in foods (English PDF)

2.1 Radionuclides

It refers to the nuclides having radioactivity. In accordance with its source, it

can be divided into two categories. natural radionuclides and artificial

radionuclides. The common forms of decay of radionuclides are alpha decay,

beta decay and gamma decay.

2.2 Carrier

It refers to a substance that can carry a certain trace substance together to

participate in a chemical or physical process. The amount of the radionuclides

for the radiochemical operation is often very small, so it is difficult to separate

or transfer it using the common amount substance treatment method. However,

the use of the stable isotope which is same as the radionuclides in chemical

properties OR the substance which is similar to the radionuclides in chemical

properties as the carrier to make the both jointly participate in the entire

treatment process, can effectively settle this problem.

3.1 General sampling shall follow the sampling requirements as specified in

GB/T 5009.1.

3.2 The amount of the sample required for the test may be determined in

accordance with the sample amount as required by the test method used OR

the dust ratio between the dust consumption by the sample and this food. The

sampling amount shall be not less than 3 times the sample amount as required

for the test, AND the sample is divided into 3 equivalent parts after being mixed

uniformly, one part for test, AND the other two parts for re-test, reference or

arbitration.

4.6.3 It shall strictly control the temperature during the ashing process (it may

use quartz thermometer or calibrated automatic temperature controller for

controlling), so as to avoid the loss of radionuclides or sample sintering.

4.6.4 For rice and other foods which are difficult to be ashed, it may take it out

at the final stage of ashing, cool it down, AND add appropriate amount of nitric

acid, hydrogen peroxide or sodium nitrite and other ashing agent to speed up

the ashing rate; after being evaporated in the electric furnace, it shall be ashed

continuously in the muffle furnace, BUT it shall also pay attention to the impact

of the ashing agent onto the measurement result; if necessary, it can make

corrections OR treat the rice after being boiled and swelled or the bean after

being soaked and pulped, which can apparently speed up the ashing rate.

4.6.5 The carrier elements and the tracer radioisotopes shall be added into the

sample before ashing.

4.6.6 The ashed food ash shall be placed in the drier to cool it to room

temperature, weighed, AND calculated of the ash/fresh ratio.

4.6.7 The food ash is placed in the porcelain evaporate dish, ground fine by

millet pestle or glass rod, mixed uniformly, passed through the 180 µm sieve,

dried at 110 °C, AND stored in the drier or grinding bottle to prepare for use.

4.7 Special requirements for sample pretreatment

Special requirements for pretreatment in certain radionuclide testing will be

specified in the corresponding standards.

5.1 If there are two or more test methods for the same test item, such methods

can be selected based on actual conditions, BUT the first method will be used

as an arbitration method, which shall be selected for the arbitration test.

5.2 When determining the measurement efficiency or chemical recovery rate, it

shall use a certified standard solution or standard reference substance for

preparation in accordance with standard method.

5.3 During the test, the chemical method shall be performed on a parallel

sample, AND the gamma spectrum and other physical methods shall be performed

on parallel samples as practical as possible.

5.4 The water used for the inspection and analysis method shall, unless

otherwise specified, refer to the distilled water or deionized water the purity of

which complies with the general analysis requirements (generally it shall reach

the level I water requirements of GB/T 6682).

8.1 The test personnel shall operate in strict accordance with the analytical

procedures specified in each standard method. For toxic, harmful or potentially

hazardous reagents or materials, it shall operate strictly in accordance with the

precautions of the reagents or materials, AND do well in personal safety

protection.

8.2 In the case of unsafe factors such as poisoning, explosion, corrosion,

burns, etc., during the test process, the laboratory shall establish

corresponding contingency plans AND take special protective measures.

8.3 The taking, placement, application, and use of the radioactive standard

solution shall have appropriate shielding protection.

8.4 After the end of the test operation, it shall conduct the field surface

radioactive contamination monitoring; if the monitored results exceed the

surface contamination control level as specified in GB 18871, it shall perform

decontamination in time until it complies with requirements.

8.5 Before personnel and items leave from the laboratory, the personnel

surface and item shall be subjected to radioactive pollution monitoring; if the

monitored results exceed the surface contamination control level as specified

in GB 18871, it shall perform decontamination in time until it complies with

requirements.

8.6 General management of radioactive waste shall comply with the provisions

of GB 18871 and GB 14500.

8.7 The storage and custody of radioactive standard solutions shall comply

with the requirements of WS 457.

9.1 As for the test results, it shall report the arithmetic mean of the measured

values of the parallel samples, AND report the number of digits or the effective

digits after the decimal point of the calculation result. The number of effective

digits shall comply with the requirements of GB 14882, AND the rounding off of

the values shall comply with the provisions of GB/T 8170.

9.2 The units of the test results shall be in the legal unit of measurement AND

shall be in accordance with the corresponding units in GB 14882.

9.3 For the test results below the detection limit, it is reported as "less than the

detection limit", AND meanwhile provide the detection limit (the calculation of

the detection limit can be found in GB/T 5009.1 or GB 14883).

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