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GB 14883.7-2016: National Food Safety Standard -- Food -- Determination of natural thorium and uranium for radioactive materials in foods
Status: Valid GB 14883.7: Evolution and historical versions
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National Food Safety Standard -- Food -- Determination of natural thorium and uranium for radioactive materials in foods
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GB 14883.7-2016
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| GB 14883.7-1994 | English | 479 |
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Examination of radioactive materials for foods. Determination of natural thorium and uranium
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GB 14883.7-1994
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PDF similar to GB 14883.7-2016
Basic data | Standard ID | GB 14883.7-2016 (GB14883.7-2016) | | Description (Translated English) | National Food Safety Standard -- Food -- Determination of natural thorium and uranium for radioactive materials in foods | | Sector / Industry | National Standard | | Classification of Chinese Standard | C53 | | Classification of International Standard | 67.040 | | Word Count Estimation | 11,144 | | Date of Issue | 2016-08-31 | | Date of Implementation | 2017-03-01 | | Older Standard (superseded by this standard) | GB 14883.7-1994 | | Regulation (derived from) | Announcement of the State Administration of Public Health and Family Planning 2016 No.11 |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 14883.7-2016: National Food Safety Standard -- Food -- Determination of natural thorium and uranium for radioactive materials in foods
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(Food safety national standard - Radioactive material in foods - Determination of natural thorium and uranium)
National Standards of People's Republic of China
National Food Safety Standard
Determination of radioactive materials of natural uranium and thorium
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 14883.7-1994 "Examination of radioactive materials in food Determination of natural thorium and uranium."
This standard compared with GB 14883.7-1994, the main changes are as follows.
--- Standard name was changed to "national food safety standard radioactive materials for foods - Determination of natural thorium and uranium.";
--- Sort out and changed the order of some of the terms and formulas;
--- Remove the determination of natural uranium extracted with ethyl acetate - Optical fluorescence spectrometry, trialkyl phosphine oxide (TRPO) Extraction - Optical fluorescence
Spectrophotometric and visual fluorescence;
--- Natural thorium and natural uranium assay method N235 extraction - spectrophotometry of "N235" to "TOA" instead.
National Food Safety Standard
Determination of radioactive materials of natural uranium and thorium
1 Scope
This standard applies to the determination of various foods natural thorium and uranium.
Determination of natural thorium first method TOA extraction - spectrophotometry
Principle 2
Food ash with nitric and perchloric acid leaching solution was concentrated phosphate precipitation of uranium and thorium in the presence of aluminum nitrate salting agent trioctylamine
From nitric acid solution while thorium and uranium extraction, first with 8mol/L hydrochloric acid solution back-extracted thorium, uranium back-extracted with water, respectively, uranium reagent Ⅲ
Color, spectrophotometric measurement. The method can be used in food uranium and thorium jointly or separately test.
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 TOA ([CH3 (CH2) 7] 3N). commercially pure.
3.1.2 ethyl acetate (C4H8O2).
3.1.3 acetone (CH3COCH3).
3.1.4 cyclohexane (C6H12).
3.1.5 nitric acid (HNO3).
3.1.6 of aluminum nitrate [Al (NO3) 3].
3.1.7 Ammonia (NH3 · H2O).
3.1.8 Ammonium nitrate (NH4NO3).
3.1.9 Uranium reagent Ⅲ (C22H18As2N4O14S2).
3.1.10 oxalic acid (H2C2O4).
3.1.11 hydrochloric acid (HCl). pure class distinctions.
3.1.12 urea [CO (NH2) 2].
3.1.13 n-octanol (C8H18O).
3.2 reagent preparation
3.2.1 10% TOA extraction solvent. the TOA 50mL, 50mL ethyl acetate, 50mL acetone, 2.5mL octanol mixed
After cyclohexane diluted to 500mL, and then 2mol/L nitrate solution and extracted wash balanced stand.
3.2.2 aluminum nitrate solution. Weigh 500g of aluminum nitrate, add a small amount of water and ammonia 33mL, diluted with water heated to dissolve 500mL, filter
After use.
3.2.3 saturated ammonium nitrate solution. formulated with 2mol/L nitric acid solution.
3.2.4 0.03% uranium reagent Ⅲ- saturated oxalic acid solution. Weigh 0.3g of uranium reagent Ⅲ, dissolved in water (if not completely dissolved, add a small amount of hydrogen can be
Sodium), diluted to 1000mL. Before using this solution was poured a small vial, oxalic acid was added to saturation.
3.2.5 8mol/L hydrochloric acid solution. amount of 333mL of hydrochloric acid, diluted with water to 500mL, was added about 1g of urea.
3.3 Standard Solution
Thorium standard solution. take 0.600g thorium nitrate [Th (NO3) · 4H2O] was dissolved 50mL5mol/L nitric acid solution into the 500mL
Flask with 0.5mol/L dilute nitric acid. This stock solution Calibration by gravimetric method. Press the calibration results with 1mol/L nitrate will certainly
Stock solution was diluted to a precise amount of standard solution of thorium 1.00μgTh/mL of.
Calibration. Imbibe 30.0mL stock solution in a beaker, add 70mL water, heated to about 80 ℃, using phenolphthalein as an indicator with ammonia
Water precipitate thorium. The precipitate was filtered with filter paper ash, 0.1% aqueous ammonia after washing several times, has been placed in the crucible constant drying, carbonization, 900 ℃ burning
Into thorium dioxide, constant, calculate the exact thorium content.
4 instruments and equipment
Spectrophotometer. 72-type or other type, 3cm cuvette.
Step 5 Analysis
5.1 Working curve drawn thorium
8 in a separatory funnel and added to each 10mL1mol/L solution of nitric acid, were suction equivalent 0μg, 0.3μg, 0.5μg, 0.7μg,
1.0μg, 2.0μg, 3.0μg, 4.0μg thorium thorium standard solution, according to 5.3.4 - 5.3.5 Determination of thorium absorbance as ordinate, the actual join
Thorium amount abscissa mapping.
5.2 Sampling and pretreatment
Sampling and pretreatment according to the provisions of GB 14883.1.
5.3 Preparation of sample and assay
5.3.1 Weigh 2.00g (accurate to 0.001g) samples less than 60mL gray porcelain evaporating dish (rice, corn and meat and other calcium ash samples
G of ash per 50mgCa proportion of added calcium carrier solution), was added 10mL of concentrated nitric acid in the sand bath slowly evaporated to dryness (Pan Evaporation
When the surface to be stamped dish against liquid spills). The evaporating dish turn muffle furnace burning 500 ℃ 10min (sample ash after burning if the black or gray
When the color, repeat the acid leach, and then burning process 1) was added 10mL8mol/L nitrate removed after cooling, filtered hot after heating to dissolve.
8mol L washing/nitric acid by evaporation pan 2 to 3 times, washed with hot dilute nitric acid residues and evaporation pan 2 to 3 times. The filtrate and washings were combined
In the centrifuge tube.
5.3.2 to 5.3.1 with stirring dropping ammonia leach solution, the solution was adjusted pH = 9 so that a white precipitate, heating cohesion. After cooling centrifugation,
The supernatant was discarded. The precipitate was washed once with water, centrifuged, the supernatant was discarded.
5.3.3 solution of concentrated nitric acid into a centrifuge tube, the precipitate just dissolves. The solution was transferred to a separatory funnel 60mL, 15mL with aluminum nitrate solution
Centrifuge tube and washed 2 times, washings were combined into a separatory funnel.
5.3.4 plus 15mL10% TOA extraction agent into a separatory funnel and extracted 5min, after the stationary phase aqueous phase was discarded. 5mL saturated with nitrate
Ammonium solution extracted wash.
5.3.5 extracted organic phase washed successively with 5.0mL and 3.5mL8mol/L hydrochloric acid, and extracted each back-extracted 5min. Secondary stripping
Take liquid were combined in 10mL colorimetric tube, add 0.3g of urea, after the oscillation is completely dissolved, 1.00mL0.03% uranium oxalate saturation reagent Ⅲ-
Solution, 8mol/L hydrochloric acid, dilute to the mark. Shake in a spectrophotometer (wavelength 665nm, 3cm cuvette) to 8.5mL
8mol/L hydrochloric acid was added instead of the sample color-developing agent as a zero value, the colorimetric measuring the absorbance of thorium. Isolated thorium content from the working curve.
The organic phase may be used for the determination of uranium (uranium can be measured in step 17.3.6).
5.4 Determination of the chemical recovery
Accurately weighed sample analysis taken equal with the amount of ash in the ash samples 60mL porcelain evaporating dish, add 2.0mL standard solution and thorium
10mL of nitric acid, 5.3.1 ~ 5.3.5 operating in parallel with the sample not added thorium standard solution. According to the measured thorium content, according to equation (1) Calculation of thorium
Chemical recovery.
R =
A'-N
A0
(1)
Where.
R --- thorium chemical recovery;
A '--- standard solution was added thorium samples measured thorium content in micrograms (μg);
When N --- check sample measurement curve obtained from the thorium thorium content in micrograms (μg);
A0 --- added the amount of thorium, in micrograms (μg).
5.5 blank test
Do not add sample ash 5.3.1 ~ 5.3.5 measurement program to 8.5mL8mol/L hydrochloric acid in the cuvette reagent was added as a zero
Value, measured under the same conditions as the absorbance of the reagent blank should be corrected in the calculation result.
6 expression analysis
Natural thorium content in food by the formula (2).
A =
NM
WR
(2)
Where.
A --- food natural thorium content in micrograms per kilogram (μg/kg);
When N --- check sample measurement curve obtained from the thorium thorium content in micrograms (μg);
M --- fresh ash, in units of grams per kilogram (g/kg);
W --- ash sample quality analysis, in grams (g);
R --- thorium chemical recovery.
7 Other
Under typical conditions, the detection limit of the method was 3.47 × 10-8g/g ash.
Determination of natural thorium second method PMBP extraction - spectrophotometry
Principle 8
Food ash with nitro hydrochloric acid leaching, precipitation carrying thorium oxalate, 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (referred PMBP) Crafts
After extraction and isolation, in 6mol/L HCl medium, uranium chromogenic reagent Ⅲ spectrophotometric assay.
9 Reagents and materials
9.1 Reagents
9.1.1 oxalic acid (H2C2O4).
9.1.2 sulfosalicylic acid (C7H6O6S · 2H2O).
9.1.3 tartaric acid (C4H6O6).
9.1.4 ascorbic acid (C6H8O6).
9.1.5 Ammonia (NH3 · H2O).
9.1.6 hydrochloric acid (HCl).
9.1.7 nitric acid (HNO3).
9.1.8 perchloric acid (HClO4).
9.1.9 Phenyl-3-methyl-4-benzoyl-5-pyrazolone PMBP (C17H14N2O2).
9.1.10 anhydrous calcium chloride (CaCl2).
9.1.11 uranium reagent Ⅲ (C22H18As2N4O14S2).
9.2 reagent preparation
9.2.1 0.03% uranium reagent Ⅲ- saturated solution of oxalic acid. with 3.2.4.
9.2.2 PMBP extraction agent. PMBP 0.3% xylene solution.
9.2.3 oxalic acid solution
9.2.3.1 10% oxalic acid solution. Weigh 10g of oxalic acid is dissolved in an appropriate amount of water, diluted with water to 100mL.
9.2.3.2 0.8% oxalic acid solution. Weigh 0.8g of oxalic acid is dissolved in an appropriate amount of water, diluted with water to 100mL.
9.2.4 10% sulfosalicylic acid solution. Weigh 10g sulfosalicylic acid dissolved in an appropriate amount of water, diluted with water to 100mL.
9.2.5 10% tartaric acid solution. Weigh 10g tartaric acid is dissolved in an appropriate amount of water, diluted with water to 100mL.
9.2.6 hydrochloric acid solution
9.2.6.1 0.1mol/L hydrochloric acid solution. amount of 1mL hydrochloric acid diluted with water to 120mL.
9.2.6.2 6mol/L hydrochloric acid solution. Measure 50mL of hydrochloric acid diluted with water to 100mL.
9.2.7 1.1 ammonia. Measure 50mL ammonia diluted with water to 100mL.
9.2.8 nitro hydrochloric acid. one volume of hydrochloric acid and nitric acid is mixed with 3 volumes, also known as aqua regia.
9.3 standard solution
9.3.1 Thorium standard solution. Same as 3.3.
9.3.2 40mgCa/mL Calcium Carrier solution. Weigh 111g of anhydrous calcium chloride was dissolved in 0.1mol/L hydrochloric acid, diluted with water to 1L.
10 instruments and equipment
Spectrophotometer. Chapter 4 of the same.
11 analysis steps
11.1 Draw the curve
Pipette equivalent 0μg, 0.3μg, 0.5μg, 0.7μg, 1.0μg, 2.0μg, 3.0μg, 5.0μg, 7.0μg, 9.0μg, 10.0μg
Thorium Thorium standard solution in 10 250mL beaker, add 20mL6mol L hydrochloric acid solution /, 2mL calcium carrier solution, add water to
250mL, according to 11.3.2 - 11.3.4 operation. Draw absorbance value curve for thorium content.
11.2 Sampling and pretreatment
Sampling and pretreatment according to the provisions of GB 14883.1.
11.3 Sample preparation and assay
11.3.1 leach. Weigh 2.00g (accurate to 0.001g) evaporating dish in the ash, the ash moistened with a little water, slowly add 5mL nitro salt
Acid, cover the surface of the dish, slowly evaporated to dryness on a hot plate, add a muffle furnace, burning at 450 ℃ 0.5h, then cool. Add approximately 20mL
6mol L hydrochloric acid /, heated to boiling, to dissolve the sample. Coolish at medium speed qualitative filter paper, washed with hot acidic water evaporating dish, wash
The residue until the filtrate was colorless. Control filtrate volume of about 250mL.
11.3.2 concentration. 2g of oxalic acid was added to the filtrate, micro heat to dissolve. 1.1 ammonia to adjust the pH to about 1, the resulting oxalate precipitation.
If no white precipitate appeared, then added dropwise with stirring calcium 2mL carrier solution, it is heated, to cause a white precipitate. Heat aging, cold
But above 0.5h, centrifuged, the supernatant was discarded. 250mL1% oxalic acid solution with precipitate was washed, centrifuged, the supernatant was discarded. Precipitated with perchloric acid and
Each 5mL ~ 10mL of nitric acid dissolved and transferred to a small beaker, a small fire was evaporated to dryness.
11.3.3 Extraction Separation. evaporated and cooled, add 10mL water, 5mL10% sulfosalicylic acid solution, about 0.1g solid ascorbic acid with
1.1 ammonia to adjust the pH to about 1, poured into a separatory funnel, washed with a little beaker and poured into the same hopper. Plus 15mL0.3% PMBP-
Xylene solution, and extracted 2min ~ 3min, after layering clear aqueous phase discarded. With 10mL0.1mol/L hydrochloric acid solution and extracted organic phase is washed, discarded
The aqueous phase. With 15mL6mol/L hydrochloric acid solution back-extracted 2min ~ 3min, standing layered clear, the aqueous phase into a 25mL capacity
Bottle, then 2mL6mol L hydrochloric acid solution/organic phase back-extracted once combined anti extracts.
11.3.4 to 11.3.3 flask followed by the addition of about 0.1g ascorbic acid, 1mL10% oxalic acid solution, 1mL10% tartaric acid solution and
2.00mL0.05% uranium Ⅲ reagent solution to 6mol/L hydrochloric acid solution was diluted to the mark. Shake, place 15min later to 17mL
6mol/L hydrochloric acid solution instead of sample solution plus reagent as a zero value, thorium measured absorbance at 665nm wavelength. Check from the working curve
The corresponding thorium content.
11.4 Determination of the chemical recovery
An analytical sample was added in the same amount of ash in the thorium standard solution 2.00mL, program operation according to the determination, the absorbance was measured according to equation (1) calculate the return
Yield.
11.5 blank test
After the sample is not measured by the above procedures ash to 17mL6mol L hydrochloric acid solution/reagent is added as zero value, under the same conditions
As a reagent blank absorbance was measured, the results should be corrected in the calculation.
12 analysis results presentation
With Chapter 6.
Other 13
Under typical conditions, the detection limit of the method is 1 × 10-8g/g ash.
Determination of natural uranium first method TOA extraction - spectrophotometry
Principle 14
With Chapter 2. The combined organic phase was back-extracted thorium after 0.2mol/L nitric acid solution back-extracted uranium. Uranium reduction with zinc particles after being tetravalent,
Uranium chromogenic reagent Ⅲ spectrophotometric determination of uranium.
15 Reagents and materials
15.1 Reagents
15.1.1 arsenic-free zinc tablets. diameter of 2mm or less circular zinc particles is appropriate.
15.1.2 perchloric acid (HClO4).
15.1.3 with 3.1.
15.2 reagent preparation
With 3.2.
15.3 standard solution
Uranium standard solution. Accurately weigh 1.179g by 850 ℃ calcined eight three uranium oxide (excellent pure) with 10mL of hydrochloric acid and 3mL too
Hydrogen peroxide dissolved by heating steam to near dryness. Then add 20mL water, so completely dissolved into 1000mL volumetric flask, add 0.1mol/L salt
Acid solution, shake to 1.00mgU/mL stock solution. Then the desired concentration of 0.1mol/L hydrochloric acid solution was further diluted,
Uranium standard solution was accurately prepared a series of different concentrations.
16 instruments and equipment
With Chapter 4.
17 analysis steps
Draw 17.1 of uranium curve
8 in a separatory funnel and added to each 10mL1mol/L solution of nitric acid, were suction equivalent 0μg, 0.3μg, 0.5μg, 0.7μg,
1.0μg, 2.0μg, 3.0μg, 4.0μg uranium standard solution of uranium, thorium extraction by organic 5.3.4,5.3.5 anti phase after the sample according to 17.3.6 Uranium
Determined by the same method measured absorbance as ordinate uranium, uranium added to the actual amount of the abscissa, drawing working curve.
17.2 Sampling and pretreatment
Sampling and pretreatment according to the provisions of GB 14883.1.
17.3 Sample preparation and assay
17.3.1 with 5.3.1.
17.3.2 with 5.3.2.
17.3.3 with 5.3.3.
17.3.4 with 5.3.4.
17.3.5 extracted organic phase was washed successively with 5.0mL and 3.5mL8mol/L hydrochloric acid, and extracted each back-extracted 5min (secondary stripping
Take for thorium were combined measurement, the step of determining thorium can be accessed 5.3.5). Reserved organic phase after back-extraction of thorium uranium for measurement.
17.3.6 In 17.3.5 After the organic phase was added 25mL0.2mol/L nitrate, back extraction 5min, the stationary phase stratified water into the 100mL
Beaker. The aqueous phase was evaporated to dryness on a sand bath, adding nitric acid and perchloric acid each 2mL (added along the beaker wall). After evaporated plus 2mL nitric acid, evaporated to dryness
After cooling. Respectively 4mL, 2mL and 2mL8mol/L hydrochloric acid sequentially residue was dissolved and transferred to 10mL colorimetric tube. Adding about 0.2g
Ascorbic acid and zinc particles and 0.3g urea 0.5g, shaking from time to time, the reaction was complete halt uranium plus 1.00mL reagent Ⅲ- oxalic acid solution to
8mol/L hydrochloric acid, dilute to the mark. Determination of uranium and thorium measuring absorbance at the same conditions. Isolated from the working curve corresponding uranium
Uranium content.
17.4 Determination of the chemical recovery
Accurately weighed sample analysis taken equal with the amount of ash in the ash samples 60mL porcelain evaporating dish, add 2.0mL standard solution and uranium
10mL of nitric acid, according to 17.3.1 - 17.3.6 and uranium standard solution not applied sample parallel operation. According to the measured uranium content, according to equation (3) Calculation of uranium
Chemical recovery.
R =
A'-N
A0
(3)
Where.
R --- uranium chemical recovery;
A '--- uranium standard solution added to the sample measured thorium content in micrograms (μg);
When N --- check from the uranium sample measurement curve obtained uranium content in micrograms (μg);
--- The A0 added in an amount of uranium, in micrograms (μg).
17.5 blank test
Do not add sample ash 17.3.1 - 17.3.6 by measurement program to 8.5mL8mol/L hydrochloric acid in the cuvette reagent was added as a zero
Value, measured under the same conditions as the absorbance of the reagent blank should be corrected in the calculation result.
18 analysis results presentation
(4) to calculate the concentration of natural uranium in food by the formula.
A =
NM
WR
(4)
Where.
A --- concentration of natural uranium in food, in micrograms per kilogram (μg/kg);
--- The N in formula (3);
M --- ash sample fresh, in units of grams per kilogram (g/kg);
W --- ash samples were analyzed by mass, in grams (g);
R --- chemical recovery of uranium, with the formula (3).
Other 19
Under typical conditions, the detection limit of the method was 9.47 × 10-8g/g ash.
Determination of natural uranium a second laser fluorescence method
Principle 20
Food ash of sodium used in certain acidity, adding fluorescence enhancer, and make the sample solution of uranyl ions form complexes.
Fluorescence laser (wavelength 337nm) excitation radiation, the use of "standard addition method" quantitative determination of uranium.
21 Reagents and materials
21.1 Reagents
21.1.1 sodium persulfate (Na2S2O8). can also be used potassium persulfate (K2S2O8).
21.1.2 fluorescence enhancer [interference (uranium) fluorescent reagent]. fluorescence enhancement in multiples of no less than 100 times.
21.1.3 nitric acid (HNO3).
21.1.4 Sodium hydroxide (NaOH).
21.2 standard solution
21.2.1 1.00mgU/mL uranium stock standard solution. with 15.3.
21.2.2 1.00μgU/mL uranium standard solution. acidified to pH = 2 water 1.00mL uranium standard stock solution was diluted to 1000mL.
22 instruments and equipment
22.1 Laser uranium analyzer or laser - Time-resolved luminescence analyzer. detection limit 0.05μg/kg.
22.2 micropipette. 5μL.
22.3 quartz glass.
23 analysis steps
23.1 Sampling and pretreatment
Sampling and pretreatment according to the provisions of GB 14883.1.
23.2 Sample preparation and assay
23.2.1 Weigh the sample ashes 50.0mg, into 50mL conical flask. Was added 20mL of water and 2.0g of sodium persulfate, covered with a watch glass, sand
The bath was heated with stirring occasionally, until after the cessation of fizzy evaporated to dryness. If you still have evaporated when the bubble can then add about 20mL water, cover surface
Dish, heated on a hot plate until no bubbles evaporated. After the solid was melted, was added 10mL of water to dissolve. After slightly heated transfer tube from
Heart or filtration. Again centrifuge tubes or triangular beaker 10mL distilled water and 3-5 drops of nitric acid, a little heat after centrifugation or filtration. Supernatant
The filtrate solution or combined in 25mL volumetric flask, using 10mol/L nitric acid or sodium hydroxide to adjust the pH 3-4, diluted with water to the mark.
23.2.2 4.50mL sample solution was taken quartz cuvette, measuring the fluorescence intensity, the count of the instrument of N0; 0.5mL was added to the sample fluorescence
Enhancers, thoroughly mixed, the fluorescence intensity measuring instrument counts N1; the sample was added to 5.0μL1.00μgU/mL standard solution of uranium charge
Sub-mixing, measuring the fluorescence intensity of the instrument count N2.
23.3 Determination of the chemical recovery
Weigh 50.0mg ash sample in 50mL conical flask was added 5.0μL1.00μgU/mL standard solution of uranium, according to the measurement program
23.2.1,23.2.2 measured in the same amount of uranium, according to equation (5) calculation of chemical recovery.
R =
5N'1-4.5N'0
N'2-N'1 -
5N1-4.5N0
N2-N1
(5)
Where.
R --- uranium chemical recovery;
Plus enhancer when N'1 --- fluorescence recovery after measuring the fluorescence intensity of reading;
N'0 --- plus fluorescence intensity of the fluorescence enhancer readings before when the recovery was measured;
When N'2 --- recoveries were added to the standard solution of uranium after reading the fluorescence intensity;
N1 --- plus fluorescence intensity of the fluorescence enhancer after reading the sample is measured;
N0 --- plus fluorescence intensity of fluorescence readings enhancer before the sample is measured;
The fluorescence intensity readings N2 --- sample measurement solution when added to standard uranium after.
23.4 blank test
Without food ash, determine the reagent blank value by the measurement program, the results should be corrected in the calculation.
24 analysis results presentation
Food concentration of natural uranium by formula (6) Calculated.
A =
(5N1-4.5N0) M
(N2-N1) WR
(6)
Where.
A --- food natural uranium concentrations in micrograms per kilogram (μg/kg);
N1 --- plus fluorescence intensity of the fluorescence enhancer after reading the sample is measured;
N0 --- plus fluorescence intensity of fluorescence readings enhancer before the sample is measured;
M --- ash sample fresh, in units of grams per kilogram (g/kg);
N2 --- sample measurement standard uranium solution was added after the fluorescence intensity readings;
W --- ash samples were analyzed by mass, in grams (g);
R --- uranium chemical recovery.
Other 25
Under typical conditions, the detection limit of the method is 4 × 10-7g/g ash.
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