|
US$159.00 · In stock
Delivery: <= 3 days. True-PDF full-copy in English will be manually translated and delivered via email.
GB 14883.2-2016: National Food Safety Standard -- Determination of radioactive material -- Hydrogen
Status: Valid GB 14883.2: Evolution and historical versions
| Standard ID | Contents [version] | USD | STEP2 | [PDF] delivered in | Standard Title (Description) | Status | PDF |
| GB 14883.2-2016 | English | 159 |
Add to Cart
|
3 days [Need to translate]
|
National Food Safety Standard -- Determination of radioactive material -- Hydrogen
| Valid |
GB 14883.2-2016
|
| GB 14883.2-1994 | English | 239 |
Add to Cart
|
3 days [Need to translate]
|
Examination of radioactive materials for foods. Determination of hydrogen-3
| Obsolete |
GB 14883.2-1994
|
PDF similar to GB 14883.2-2016
Basic data | Standard ID | GB 14883.2-2016 (GB14883.2-2016) | | Description (Translated English) | National Food Safety Standard -- Determination of radioactive material -- Hydrogen | | Sector / Industry | National Standard | | Classification of Chinese Standard | C53 | | Classification of International Standard | 67.040 | | Word Count Estimation | 8,891 | | Date of Issue | 2016-08-31 | | Date of Implementation | 2017-03-01 | | Older Standard (superseded by this standard) | GB 14883.2-1994 | | Regulation (derived from) | Announcement of the State Administration of Public Health and Family Planning 2016 No.11 |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 14883.2-2016: National Food Safety Standard -- Determination of radioactive material -- Hydrogen
---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order.
(Food safety national standard - DETERMINATION OF RADIOACTIVE HYDROGEN - 3 IN FOODS)
National Standards of People's Republic of China
National Food Safety Standard
Determination of radioactive materials in foods hydrogen - 3
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 14883.2-1994 "test radioactive materials for foods - 3 Determination of hydrogen."
This standard compared with GB 14883.2-1994, the main changes are as follows.
--- Standard name was changed to "national food safety standard radioactive materials in foods Determination of Hydrogen-3 ';
--- National food safety standards in accordance with the format of the text has been adjusted;
--- Supplementary analysis and refinement of the experimental procedure.
National Food Safety Standard
Determination of radioactive materials in foods hydrogen - 3
1 Scope
This standard applies to all types of foods hydrogen -3 (3H) measurement.
Principle 2
FRESH burned - oxidation, free water and organic matter in the water is converted to hydrogen all. After collecting water purification electrolysis to concentrate 3H, with liquid
Scintillation counter measuring 3H radioactivity.
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 Potassium persulfate (K2S2O8).
3.1.2 Sodium peroxide (Na2O2).
3.1.3 phosphoric acid solution. concentration of 85%, commercially available.
3.1.4 2,5-diphenyl oxazole [OC (C6H5) = NCH = CC6H5]. abbreviation PPO, pure flashes.
3.1.5 1,4-bis-2- (5-phenyl-yl) - benzene ([OC (C6H5) = CHN = C] 2C6H4). short POPOP, flashing pure.
3.1.6 naphthalene (C10H8).
3.1.7 1,4-dioxane (C4H8O2).
3.1.8 The bottom water. conductivity less than 2 × 10-6Ω · cm-1. The water should be taken from the bottom level as low as possible 3H activity concentration of water, such as (deep)
groundwater. Distillation to obtain water samples Determination of 3H activity concentration (Bq/m3), and record the measurement date (t = 0). Packed in borosilicate glass bottles
Constant temperature kept in the dark.
3.2 reagent preparation
Scintillation fluid. Take 6gPPO, 0.3gPOPOP naphthalene and 100g, was dissolved in purified distilled 1,4-dioxane (dioxane
Ring) and diluted to 1L. Save wrapped in black good brown bottle, dark standby. PPO and POPOP flashes are pure. You can also use
Have a good product with a commercial scintillation fluid, but should try to use low toxicity, high flash point solubility good safe and efficient products. Users should test alternative
Goods scintillation fluid performance and optimal conditions to ensure acceptability.
3.3 Standard
Standard 3H Water. known accurately 3H activity, was diluted with water background backup.
4 instruments and equipment
4.1 liquid scintillation counter. background count rate of not more than 60 counts/min, 3H counting efficiency of not less than 20%, preferably at a constant temperature operation.
4.2 3H oxidation combustion devices. Figure 1.
Explanation.
1 --- combustion chamber;
2 --- oxidation chamber;
3 --- high-temperature furnace;
4 --- thermocouple;
5 --- received water bottles;
6 --- condenser.
Figure 1 3H oxidation combustion device
4.3 3H electrolysis enrichment device. Figures 2 and 3.
Explanation.
1 --- electrolytic cell;
2 --- holder;
3 --- cooling pipes.
2 3H electrolysis enrichment device of FIG.
Explanation.
1 --- rubber stopper;
2 --- a nickel cathode;
3 --- nickel anodes;
4 --- plastic ring.
Figure 3 electrode
Step 5 Analysis
5.1 Sampling and pretreatment
Sampling and pretreatment according to the provisions of GB 14883.1.
Combustion and oxidation of the sample 5.2
5.2.1 weighed 1.00kg washed, dried food fresh sample was charged in the combustion chamber 3H oxidation combustion device.
5.2.2 First pass oxygen flow rate control in 0.5L/min ~ 0.7L/min, catch air device inside the net.
5.2.3 the power is turned on high-temperature furnace. The temperature of the oxidation chamber is raised to 700 deg.] C, and then heating the combustion chamber, when the temperature was raised to 100 deg.] C, water alone
It flows into the receiving flask. Maintain this temperature until the water flows out slow and then slowly warmed.
5.2.4 When the temperature rose to 200 ℃ ~ 300 ℃, warming slowly as possible, and carefully observe the situation through oxygen. General combustion chamber temperature was raised to
On no more than 500 ℃ fraction outflow.
5.2.5 controlling the temperature at 600 ℃, continue to burn for some time, so that complete oxidation of food samples, then cuts off the heating and ventilation.
Combustion chamber gas generated by the oxidation is oxidized by water vapor condenser collected in the receiving flask.
5.3 purified water samples
By measuring the total volume of water collected later transferred to 500mL distillation flask was added 20g ~ 30g potassium persulfate, peroxide reflux for approximately 2h, if dissolved
Still colored liquid can be added after about 10g of potassium persulfate reflux for 2h. Repeat the operation until complete oxidation reflux fade. The retort access
Distillation apparatus was distilled, the resulting water-necked flask sealed in the mill.
5.4 electrolytic concentration
5.4.1 electrolysis process is carried out in FIG. 2 device. Before recording the electrolysis of purified water sample volume and a 1% sodium peroxide solution dubbed as electricity
Hydrolyzate.
5.4.2 Electrolytic nickel electrode before (see Figure 3) in advance immersed in hot dilute phosphoric acid solution for a few minutes, rinse with water after drying out, and then into electricity
Solution pool (see Figure 2).
5.4.3 electrolysis current density of 65mA/cm2, with water cooling, each sample electrolysis of water at the same time, the symmetrical position in the electrolysis cell
Electrolysis of water samples added two other standard 3H sample volume of water to determine the electrolytic process 3H recovery.
5.4.4 electrolysis electrolyte until the volume is reduced by about 10 times over, electrolytic recording volume.
5.4.5 After the completion of electrolysis, direct distillation sample three times the concentration of 3H the water is separated from the electrolyte.
Concentration coefficient 5.4.6 electrolyzed water sample according to equation (1).
P =
Vi
Ve
(1)
Where.
P --- concentration coefficient;
Volume Vi --- sample before electrolysis of water in milliliters (mL);
Volume of the sample water after Ve --- electrolysis, in milliliters (mL).
5.4.7 standard 3H water according to step 5.4.1 ~ 5.4.5 process according to the formula (2) calculate 3H recovery electrolysis process.
Y =
IeVe
IiVi
(2)
Where.
Y --- electrolysis process 3H recovery;
Ie --- standard 3H radioactivity after electrolysis units of becquerels (Bq);
Volume Ve --- standard 3H water electrolysis after milliliters (mL);
Ii --- standard 3H radioactivity before the water electrolysis unit is becquerel (Bq);
Volume Vi --- standard 3H water electrolysis before milliliters (mL).
5.5 Sample Preparation
5.5.1 Preparation of test samples
Imbibe after concentrated water samples 2.00mL and 8.00mL scintillation fluid mixing, add 10mL sample counting vials, screw caps and shaken
Mixed for use.
The bottom sample preparation 5.5.2
After this bottom water by electrolysis 5.4 after distillation, imbibe distilled water samples 2.00mL and 8.00mL scintillation fluid mixing, add 10mL sample
Product count bottle, screw cap, shaking after mixing for use.
5.5.3 Preparation of standard samples
Imbibe 3H standard solution 2.00mL and 8.00mL water samples scintillation fluid, add 10mL sample counting vials, screw caps, vibration
Swing after mixing for use.
5.5.4 from light
After the prepared sample (including the bottom of the sample, the sample and standard samples), wet cotton ball with alcohol wipe clean the bottle, at the same time put
Liquid scintillation counter sample chamber, protected from light more than 12h (typically made of the same day sample into the sample chamber to the next measurement).
5.5.5 prevent cross-contamination
In the operation of each step could cause cross-contamination between samples, to avoid cross-contamination. Operating according to a low level, after high
Level order.
5.6 Measuring
5.6.1 Instrument Preparation
Debugging instrument to normal working condition. Select and determine the energy channel width 3H measurement, the instrument measuring channel the spirit of the sample being measured
Sensitivity is maximized.
Determined length measurement 5.6.2
Low sample requires a long measurement time, and measurement accuracy required, generally less than 1000min. Counting time should be able to protect
Statistical fluctuation syndrome samples to meet the measurement requirements.
5.6.3 Determination of the background count rate
Background counting time of preparation of the sample is measured to determine. For the measurement of low levels of sample counting time background samples shall
Less than 1000min.
Measuring instruments 5.6.4 Efficiency
Preparation of standard samples were measured according to equation (3) calculate the counting efficiency of the instrument.
ε =
Ns-Nb
60As
(3)
Where.
Counting efficiency ε --- instrument;
Ns --- standard sample count rate in units of counts per minute (cpm);
Nb --- samples background count rate in units of counts per minute (cpm);
As --- added to the standard sample 3H activity, units of becquerels (Bq), should be corrected to the activity detection, scintillation fluid sample mixed
The quenched material may result in counting efficiency. It can be used inside or outside the standard method standard channels ratio method quenching correction.
5.6.5 Sample Measurement
Samples should be measured in the following order. the bottom of the sample - the sample - the standard sample, measured length should be the same for each sample.
5.7 blank test
A blank test reagent should be replaced or detection of different batches of samples.
6 expression analysis
The concentration of 3H radioactivity in food by the formula (4) Calculated.
A =
(Nt-Nb) V
60VtPYεW
(4)
Where.
A --- measuring radioactivity concentration in the sample 3H, in units of becquerels per kilogram (Bq/kg);
Nt --- measuring the count rate of the sample, in units of counts per minute (cpm);
Nb --- samples background count rate in units of counts per minute (cpm);
V --- volume of water samples collected in the combustion process, in milliliters (mL);
Vt --- sample volume of water measured in milliliters (mL);
P --- concentration coefficient;
Y --- electrolysis process 3H recovery;
Counting efficiency ε --- instrument;
W --- fresh sample volume analysis of the sample, in kilograms (kg).
7 Other
Under typical conditions, the detection limit of this method was 11Bq/kg.
Tips & Frequently Asked Questions:Question 1: How long will the true-PDF of GB 14883.2-2016_English be delivered?Answer: Upon your order, we will start to translate GB 14883.2-2016_English as soon as possible, and keep you informed of the progress. The lead time is typically 1 ~ 3 working days. The lengthier the document the longer the lead time. Question 2: Can I share the purchased PDF of GB 14883.2-2016_English with my colleagues?Answer: Yes. The purchased PDF of GB 14883.2-2016_English will be deemed to be sold to your employer/organization who actually pays for it, including your colleagues and your employer's intranet. Question 3: Does the price include tax/VAT?Answer: Yes. Our tax invoice, downloaded/delivered in 9 seconds, includes all tax/VAT and complies with 100+ countries' tax regulations (tax exempted in 100+ countries) -- See Avoidance of Double Taxation Agreements (DTAs): List of DTAs signed between Singapore and 100+ countriesQuestion 4: Do you accept my currency other than USD?Answer: Yes. If you need your currency to be printed on the invoice, please write an email to [email protected]. In 2 working-hours, we will create a special link for you to pay in any currencies. Otherwise, follow the normal steps: Add to Cart -- Checkout -- Select your currency to pay. Question 5: Should I purchase the latest version GB 14883.2-2016?Answer: Yes. Unless special scenarios such as technical constraints or academic study, you should always prioritize to purchase the latest version GB 14883.2-2016 even if the enforcement date is in future. Complying with the latest version means that, by default, it also complies with all the earlier versions, technically.
|