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GB/T 13082-2021 English PDF (GBT13082-2021)
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GB/T 13082-2021: Determination of cadmium in feeds
GB/T 13082-2021
Determination of cadmium in feeds
ICS 65.120
CCSB46
National Standards of People's Republic of China
Replacing GB/T 13082-1991
Determination of Cadmium in Feed
Published on 2021-11-26
2022-06-01 Implementation
State Administration for Market Regulation
Released by the National Standardization Administration
Determination of Cadmium in Feed
1 Scope
This document describes flame atomic absorption spectrometry and graphite furnace atomic absorption spectrometry for the determination of cadmium in feed.
This document applies to the concentration of cadmium in compound feeds, concentrated feeds, concentrate supplements, additive premixed feeds, feed additives and feed ingredients.
Determination.
In this document, when the sampling volume is 5g and the constant volume is 50mL, the detection limit of flame atomic absorption spectrometry is 0.08mg/kg.
The limit of detection is 0.20mg/kg; when the sampling amount is 0.5g and the constant volume is 25mL, the detection limit of graphite furnace atomic absorption spectrometry is 0.002mg/kg,
The limit of quantitation was 0.05 mg/kg.
2 Normative references
The contents of the following documents constitute essential provisions of this document through normative references in the text. Among them, dated citations
documents, only the version corresponding to that date applies to this document; for undated references, the latest edition (including all amendments) applies to
this document.
GB/T 6682 Analysis Laboratory Water Specifications and Test Methods
GB 6819-2004 Dissolved acetylene
Preparation of GB/T 20195 Animal Feed Samples
3 Terms and Definitions
There are no terms and definitions that need to be defined in this document.
4 Principles
After dry ashing or wet digestion (microwave digestion), or hydrochloric acid dissolution, the sample is introduced into the flame or graphite furnace atom of the atomic absorption spectrophotometer.
The absorbance value is measured at a wavelength of 228.8 nm in a chemiluminizer. Within a certain concentration range, the cadmium concentration is proportional to its absorbance value. The standard curve
Line calibration quantification.
5 Reagents or materials
Warning. When using various strong acids, it should be carried out in a fume hood; when using perchloric acid for digestion, be careful not to burn it to prevent explosion.
Unless otherwise specified, only analytical grade reagents were used.
5.1 Water. GB/T 6682, Class I.
5.2 Nitric acid. excellent grade pure.
5.3 Hydrochloric acid. excellent grade pure.
5.4 Perchloric acid. excellent grade pure.
5.5 Hydrochloric acid solution (6mol/L). Dilute 500mL of hydrochloric acid (5.3) to 1000mL, and mix well.
5.6 Nitric acid solution. dilute 10 mL of nitric acid (5.2) to 1000 mL, and mix well.
5.7 Nitric acid solution (6mol/L). Dilute 43mL of nitric acid (5.2) to 100mL, and mix well.
5.8 Palladium nitrate solution (2 mg/mL). Weigh 0.20 g of palladium nitrate, dissolve in water and dilute to 100 mL, and mix well.
5.9 Ammonium dihydrogen phosphate solution (10 mg/mL). Weigh 1.00 g of ammonium dihydrogen phosphate, dissolve in water and dilute to 100 mL, and mix well.
5.10 Cadmium standard stock solution (1mg/mL). accurately weigh 1.0000g metal cadmium (certified reference material, purity 99.99%) in
In a 250mL conical flask, add 10mL of nitric acid solution (5.7), heat it on an electric hot plate to dissolve it all, transfer it to a 1000mL volumetric flask,
Add water to the mark and mix well. Stored in polyethylene bottles at 4°C, the validity period is 6 months. Or purchase certified standard solutions.
5.11 Cadmium standard intermediate solution I (10 μg/mL). accurately pipette 1 mL of cadmium standard stock solution (5.10) into a 100 mL volumetric flask, use
Dilute the nitric acid solution (5.6) to the mark and mix. Valid for 1 month.
5.12 Cadmium standard intermediate solution II (100μg/L). accurately pipette 1mL of cadmium standard intermediate solution I (5.11) into a 100mL volumetric flask,
Dilute to volume with nitric acid solution (5.6) and mix. Ready to use.
5.13 Cadmium standard series solution I. accurately pipette an appropriate volume of cadmium standard intermediate solution I (5.11) and place them in a 50mL volumetric flask, respectively.
Dilute the nitric acid solution (5.6) to the mark, mix well, and prepare the concentration of 0 μg/mL, 0.02 μg/mL, 0.04 μg/mL, 0.06 μg/mL,
Standard series solutions of 0.08μg/mL and 0.10μg/mL. Ready to use.
5.14 Cadmium standard series solution II. accurately pipette an appropriate volume of cadmium standard intermediate solution II (5.12) and place them in a 50mL volumetric flask, respectively.
Dilute the nitric acid solution (5.6) to the mark, mix well, and prepare the concentrations of 0 μg/L, 0.5 μg/L, 1.0 μg/L, 2.0 μg/L, 3.0 μg/L,
4.0μg/L standard series solution. Ready to use.
5.15 Acetylene. should meet the requirements of 3.1 in GB 6819-2004.
5.16 Medium speed filter paper.
6 Instruments and equipment
6.1 Atomic absorption spectrophotometer. with flame/graphite furnace atomizer and cadmium hollow cathode lamp.
6.2 Analytical balance. Sensitive amounts of 0.0001g and 0.01g.
6.3 Muffle furnace. the temperature can be kept at 500℃±15℃.
6.4 Porcelain crucible. 60cm3, the inner wall is smooth, not corroded or scratched.
6.5 Digestion tube.
6.6 Adjustable electric heating plate or adjustable electric furnace. the temperature range is 100℃~400℃, and the accuracy is ±5℃.
6.7 Microwave digestion apparatus. with PTFE digestion tank.
Note. The crucibles, digestion inner tanks and glassware containers used are first cleaned with hot water containing detergent ultrasonically, rinsed with water, dried, and then rinsed with nitric acid solution.
(5.7) Soak for 2 hours, rinse with water, and use after drying.
7 samples
Prepare the sample according to GB/T 20195, at least.200g, pulverize it to make it all pass through the analytical sieve with 0.425mm aperture, and put it into an airtight container
medium, spare. The particle size of feed additive samples shall be implemented in accordance with the corresponding product standards.
8 Test steps
8.1 Preparation of sample solution
8.1.1 Dry Ashing
Suitable for compound feeds, concentrated feeds, concentrate supplements and additive premixes containing organic matter, feed additives and feedstuffs
raw material.
Do two experiments in parallel. Weigh 5g of sample (accurate to 0.01g) in a porcelain crucible and place it on an adjustable electric heating plate or adjustable electric furnace
After slowly heating and carbonizing to no smoke, transfer it to a 500 ℃ muffle furnace for ashing for 5 hours, until the sample is white or off-white and has no carbon particles. if found
When there is a small amount of carbon particles, nitric acid solution (5.7) can be dripped to wet the residue, and the porcelain crucible can be moved to an adjustable electric hot plate or an adjustable electric furnace to dry on a small fire.
Dry, and then move to a muffle furnace to continue ashing until the sample is white or off-white without carbon particles.
Take out the crucible and cool to room temperature. Draw 5 mL of hydrochloric acid solution (5.5), add it dropwise to the porcelain crucible, and turn it while adding, until the solution
No bubbles overflow, then add the remaining hydrochloric acid solution, then add 5 mL of nitric acid solution (5.7), move the porcelain crucible to an adjustable electric hot plate or adjustable
On the electric furnace, slowly heat until the digestion solution reaches 2mL~3mL (be careful to prevent splashing), remove it, and cool it to room temperature. transfer the digestive juices
Into a 50mL volumetric flask, rinse the wall of the porcelain crucible with a little water for several times, incorporate it into the volumetric flask, add water to the volume, shake well, filter, and set aside. do both
Blank test.
8.1.2 Wet digestion method
It is suitable for additive premixed feed, feed additives and feed raw materials containing more organic matter.
Do two experiments in parallel. Weigh 1 g of the sample (accurate to 0.0001 g) into the digestion tube, add a small amount of water to wet it, and add 10 mL of nitric acid
(5.2), put it in a fume hood, after standing for 2 hours, add 5 mL of perchloric acid (5.4), and place it on an adjustable electric hot plate or adjustable
Heat the digestion on a small fire on the electric stove, until the digestive juice emits white smoke, remove it and cool it. Transfer the digestion solution to a 50mL volumetric flask with a little water
Rinse the digestion tube several times, put it into a volumetric flask, add water to volume, shake well, filter, and set aside. At the same time do a blank test.
8.1.3 Microwave digestion
Suitable for compound feeds, concentrated feeds, concentrate supplements and additive premixes containing organic matter, feed additives and feedstuffs
raw material.
Do two experiments in parallel. Weigh 0.3g~0.5g sample (accurate to 0.0001g) into the digestion tank, add 6mL nitric acid (5.2), spin
Tighten the jar lid, leave it for 2 hours or stand overnight, screw the lid tightly, cover the safety valve, put the digestion jar into the microwave digestion apparatus, and follow Table 1 and microwave digestion.
The operation steps and procedures of the disintegrator are used for digestion. After digestion, take out and cool to room temperature. If the residual acid in the sample digestion solution is too large, the
It is placed on an adjustable electric hot plate or an adjustable electric furnace to heat and drive off the acid, and when the volume reaches 1mL~2mL, remove it and cool it. Transfer the digestive juice to
In a 10mL or 25mL volumetric flask, rinse the digestion tank several times with a little water, incorporate it into the volumetric flask, add water to the volume, shake well, filter, and set aside. same
Do a blank test.
8.1.4 Hydrochloric acid dissolution method
Suitable for mineral feed ingredients and mineral element feed additives.
Do two experiments in parallel. Weigh 0.5g~2g of the sample (accurate to 0.0001g) into a 150mL conical flask, add 2mL of water to the sample.
Wetting, take 10 mL of hydrochloric acid solution (5.5), add it dropwise to the conical flask, and turn it while adding, until the solution has no bubbles overflowing, and then put the remaining
Add all the hydrochloric acid solution, then add 5 mL of nitric acid solution (5.7), move the conical flask to an adjustable electric hot plate or an adjustable electric furnace for low heat heating
Digest to 2mL~3mL (pay attention to prevent splashing), remove and cool. Transfer the solution to a 25mL or 50mL volumetric flask with a little water
Rinse the conical flask several times, incorporate it into a volumetric flask, add water to volume, shake well, filter, and set aside. At the same time do a blank test.
8.2 Reference Conditions for Atomic Absorption Spectrometry
Adjust to the best state according to the performance of the respective instruments, the reference conditions of the flame atomic absorption spectrometer and the graphite furnace atomic absorption spectrometer
Refer to Table 2 and Table 3 for the reference conditions of the device.
8.3 Determination
8.3.1 Flame Atomic Absorption Spectroscopy
Set the instrument to the background button mode, and adjust to the best working state, zeroing with water or the zero point of the curve, at the characteristic wavelength of cadmium element at 228.8nm
Measure the absorbance values of blank solution, cadmium standard series solution I (5.13) and sample solution in turn, take the cadmium standard series solution I (5.13)
The cadmium concentration is the abscissa, the absorbance value is the ordinate, and the standard curve is drawn, and the correlation coefficient of the standard curve is r≥0.999.Absorbance of sample solution
The degree value should be within the linear range of the standard curve. If it exceeds, it can be appropriately diluted (n times) with reference to the acid concentration of the cadmium standard series solution I (5.13).
post-measurement.
8.3.2 Graphite Furnace Atomic Absorption Spectrometry
Set the instrument to the background button mode, and adjust to the best working state. At the characteristic wavelength of cadmium element at 228.8nm, test according to 10μL
liquid, 5 μL palladium nitrate solution (5.8) and 5 μL ammonium dihydrogen phosphate solution (5.9) (the optimal injection method can be determined according to the instrument used
sample), inject the solution into the graphite furnace, and measure the absorbance values of the blank solution, the cadmium standard series solution II (5.14) and the sample solution in turn.
Taking the cadmium concentration of cadmium standard series solution II (5.14) as the abscissa and the absorbance value as the ordinate, draw a standard curve, and the correlation coefficient of the standard curve
r≥0.995.The absorbance value of the sample solution should be within the linear range of the standard curve.
The acid concentration was determined after appropriate dilution (n-fold).
9 Test data processing
9.1 Flame Atomic Absorption Spectroscopy
The content w of cadmium in the sample is calculated in mass fraction, the unit is milligram per kilogram (mg/kg), and it is calculated according to formula (1).
10 Precision
10.1 Flame Atomic Absorption Spectroscopy
Under repeatability conditions, the ratio d of the absolute difference between the two independent determination results and their arithmetic mean to the arithmetic mean,
Should meet the requirements of Table 4.
10.2 Graphite Furnace Atomic Absorption Spectrometry
Under repeatability conditions, the ratio of the absolute difference between the two independent determination results and their arithmetic mean to the arithmetic mean, d
Should meet the requirements of Table 5.
Get Quotation: Click GB/T 13082-2021 (Self-service in 1-minute)
Historical versions (Master-website): GB/T 13082-2021
Preview True-PDF (Reload/Scroll-down if blank)
GB/T 13082-2021: Determination of cadmium in feeds
GB/T 13082-2021
Determination of cadmium in feeds
ICS 65.120
CCSB46
National Standards of People's Republic of China
Replacing GB/T 13082-1991
Determination of Cadmium in Feed
Published on 2021-11-26
2022-06-01 Implementation
State Administration for Market Regulation
Released by the National Standardization Administration
Determination of Cadmium in Feed
1 Scope
This document describes flame atomic absorption spectrometry and graphite furnace atomic absorption spectrometry for the determination of cadmium in feed.
This document applies to the concentration of cadmium in compound feeds, concentrated feeds, concentrate supplements, additive premixed feeds, feed additives and feed ingredients.
Determination.
In this document, when the sampling volume is 5g and the constant volume is 50mL, the detection limit of flame atomic absorption spectrometry is 0.08mg/kg.
The limit of detection is 0.20mg/kg; when the sampling amount is 0.5g and the constant volume is 25mL, the detection limit of graphite furnace atomic absorption spectrometry is 0.002mg/kg,
The limit of quantitation was 0.05 mg/kg.
2 Normative references
The contents of the following documents constitute essential provisions of this document through normative references in the text. Among them, dated citations
documents, only the version corresponding to that date applies to this document; for undated references, the latest edition (including all amendments) applies to
this document.
GB/T 6682 Analysis Laboratory Water Specifications and Test Methods
GB 6819-2004 Dissolved acetylene
Preparation of GB/T 20195 Animal Feed Samples
3 Terms and Definitions
There are no terms and definitions that need to be defined in this document.
4 Principles
After dry ashing or wet digestion (microwave digestion), or hydrochloric acid dissolution, the sample is introduced into the flame or graphite furnace atom of the atomic absorption spectrophotometer.
The absorbance value is measured at a wavelength of 228.8 nm in a chemiluminizer. Within a certain concentration range, the cadmium concentration is proportional to its absorbance value. The standard curve
Line calibration quantification.
5 Reagents or materials
Warning. When using various strong acids, it should be carried out in a fume hood; when using perchloric acid for digestion, be careful not to burn it to prevent explosion.
Unless otherwise specified, only analytical grade reagents were used.
5.1 Water. GB/T 6682, Class I.
5.2 Nitric acid. excellent grade pure.
5.3 Hydrochloric acid. excellent grade pure.
5.4 Perchloric acid. excellent grade pure.
5.5 Hydrochloric acid solution (6mol/L). Dilute 500mL of hydrochloric acid (5.3) to 1000mL, and mix well.
5.6 Nitric acid solution. dilute 10 mL of nitric acid (5.2) to 1000 mL, and mix well.
5.7 Nitric acid solution (6mol/L). Dilute 43mL of nitric acid (5.2) to 100mL, and mix well.
5.8 Palladium nitrate solution (2 mg/mL). Weigh 0.20 g of palladium nitrate, dissolve in water and dilute to 100 mL, and mix well.
5.9 Ammonium dihydrogen phosphate solution (10 mg/mL). Weigh 1.00 g of ammonium dihydrogen phosphate, dissolve in water and dilute to 100 mL, and mix well.
5.10 Cadmium standard stock solution (1mg/mL). accurately weigh 1.0000g metal cadmium (certified reference material, purity 99.99%) in
In a 250mL conical flask, add 10mL of nitric acid solution (5.7), heat it on an electric hot plate to dissolve it all, transfer it to a 1000mL volumetric flask,
Add water to the mark and mix well. Stored in polyethylene bottles at 4°C, the validity period is 6 months. Or purchase certified standard solutions.
5.11 Cadmium standard intermediate solution I (10 μg/mL). accurately pipette 1 mL of cadmium standard stock solution (5.10) into a 100 mL volumetric flask, use
Dilute the nitric acid solution (5.6) to the mark and mix. Valid for 1 month.
5.12 Cadmium standard intermediate solution II (100μg/L). accurately pipette 1mL of cadmium standard intermediate solution I (5.11) into a 100mL volumetric flask,
Dilute to volume with nitric acid solution (5.6) and mix. Ready to use.
5.13 Cadmium standard series solution I. accurately pipette an appropriate volume of cadmium standard intermediate solution I (5.11) and place them in a 50mL volumetric flask, respectively.
Dilute the nitric acid solution (5.6) to the mark, mix well, and prepare the concentration of 0 μg/mL, 0.02 μg/mL, 0.04 μg/mL, 0.06 μg/mL,
Standard series solutions of 0.08μg/mL and 0.10μg/mL. Ready to use.
5.14 Cadmium standard series solution II. accurately pipette an appropriate volume of cadmium standard intermediate solution II (5.12) and place them in a 50mL volumetric flask, respectively.
Dilute the nitric acid solution (5.6) to the mark, mix well, and prepare the concentrations of 0 μg/L, 0.5 μg/L, 1.0 μg/L, 2.0 μg/L, 3.0 μg/L,
4.0μg/L standard series solution. Ready to use.
5.15 Acetylene. should meet the requirements of 3.1 in GB 6819-2004.
5.16 Medium speed filter paper.
6 Instruments and equipment
6.1 Atomic absorption spectrophotometer. with flame/graphite furnace atomizer and cadmium hollow cathode lamp.
6.2 Analytical balance. Sensitive amounts of 0.0001g and 0.01g.
6.3 Muffle furnace. the temperature can be kept at 500℃±15℃.
6.4 Porcelain crucible. 60cm3, the inner wall is smooth, not corroded or scratched.
6.5 Digestion tube.
6.6 Adjustable electric heating plate or adjustable electric furnace. the temperature range is 100℃~400℃, and the accuracy is ±5℃.
6.7 Microwave digestion apparatus. with PTFE digestion tank.
Note. The crucibles, digestion inner tanks and glassware containers used are first cleaned with hot water containing detergent ultrasonically, rinsed with water, dried, and then rinsed with nitric acid solution.
(5.7) Soak for 2 hours, rinse with water, and use after drying.
7 samples
Prepare the sample according to GB/T 20195, at least.200g, pulverize it to make it all pass through the analytical sieve with 0.425mm aperture, and put it into an airtight container
medium, spare. The particle size of feed additive samples shall be implemented in accordance with the corresponding product standards.
8 Test steps
8.1 Preparation of sample solution
8.1.1 Dry Ashing
Suitable for compound feeds, concentrated feeds, concentrate supplements and additive premixes containing organic matter, feed additives and feedstuffs
raw material.
Do two experiments in parallel. Weigh 5g of sample (accurate to 0.01g) in a porcelain crucible and place it on an adjustable electric heating plate or adjustable electric furnace
After slowly heating and carbonizing to no smoke, transfer it to a 500 ℃ muffle furnace for ashing for 5 hours, until the sample is white or off-white and has no carbon particles. if found
When there is a small amount of carbon particles, nitric acid solution (5.7) can be dripped to wet the residue, and the porcelain crucible can be moved to an adjustable electric hot plate or an adjustable electric furnace to dry on a small fire.
Dry, and then move to a muffle furnace to continue ashing until the sample is white or off-white without carbon particles.
Take out the crucible and cool to room temperature. Draw 5 mL of hydrochloric acid solution (5.5), add it dropwise to the porcelain crucible, and turn it while adding, until the solution
No bubbles overflow, then add the remaining hydrochloric acid solution, then add 5 mL of nitric acid solution (5.7), move the porcelain crucible to an adjustable electric hot plate or adjustable
On the electric furnace, slowly heat until the digestion solution reaches 2mL~3mL (be careful to prevent splashing), remove it, and cool it to room temperature. transfer the digestive juices
Into a 50mL volumetric flask, rinse the wall of the porcelain crucible with a little water for several times, incorporate it into the volumetric flask, add water to the volume, shake well, filter, and set aside. do both
Blank test.
8.1.2 Wet digestion method
It is suitable for additive premixed feed, feed additives and feed raw materials containing more organic matter.
Do two experiments in parallel. Weigh 1 g of the sample (accurate to 0.0001 g) into the digestion tube, add a small amount of water to wet it, and add 10 mL of nitric acid
(5.2), put it in a fume hood, after standing for 2 hours, add 5 mL of perchloric acid (5.4), and place it on an adjustable electric hot plate or adjustable
Heat the digestion on a small fire on the electric stove, until the digestive juice emits white smoke, remove it and cool it. Transfer the digestion solution to a 50mL volumetric flask with a little water
Rinse the digestion tube several times, put it into a volumetric flask, add water to volume, shake well, filter, and set aside. At the same time do a blank test.
8.1.3 Microwave digestion
Suitable for compound feeds, concentrated feeds, concentrate supplements and additive premixes containing organic matter, feed additives and feedstuffs
raw material.
Do two experiments in parallel. Weigh 0.3g~0.5g sample (accurate to 0.0001g) into the digestion tank, add 6mL nitric acid (5.2), spin
Tighten the jar lid, leave it for 2 hours or stand overnight, screw the lid tightly, cover the safety valve, put the digestion jar into the microwave digestion apparatus, and follow Table 1 and microwave digestion.
The operation steps and procedures of the disintegrator are used for digestion. After digestion, take out and cool to room temperature. If the residual acid in the sample digestion solution is too large, the
It is placed on an adjustable electric hot plate or an adjustable electric furnace to heat and drive off the acid, and when the volume reaches 1mL~2mL, remove it and cool it. Transfer the digestive juice to
In a 10mL or 25mL volumetric flask, rinse the digestion tank several times with a little water, incorporate it into the volumetric flask, add water to the volume, shake well, filter, and set aside. same
Do a blank test.
8.1.4 Hydrochloric acid dissolution method
Suitable for mineral feed ingredients and mineral element feed additives.
Do two experiments in parallel. Weigh 0.5g~2g of the sample (accurate to 0.0001g) into a 150mL conical flask, add 2mL of water to the sample.
Wetting, take 10 mL of hydrochloric acid solution (5.5), add it dropwise to the conical flask, and turn it while adding, until the solution has no bubbles overflowing, and then put the remaining
Add all the hydrochloric acid solution, then add 5 mL of nitric acid solution (5.7), move the conical flask to an adjustable electric hot plate or an adjustable electric furnace for low heat heating
Digest to 2mL~3mL (pay attention to prevent splashing), remove and cool. Transfer the solution to a 25mL or 50mL volumetric flask with a little water
Rinse the conical flask several times, incorporate it into a volumetric flask, add water to volume, shake well, filter, and set aside. At the same time do a blank test.
8.2 Reference Conditions for Atomic Absorption Spectrometry
Adjust to the best state according to the performance of the respective instruments, the reference conditions of the flame atomic absorption spectrometer and the graphite furnace atomic absorption spectrometer
Refer to Table 2 and Table 3 for the reference conditions of the device.
8.3 Determination
8.3.1 Flame Atomic Absorption Spectroscopy
Set the instrument to the background button mode, and adjust to the best working state, zeroing with water or the zero point of the curve, at the characteristic wavelength of cadmium element at 228.8nm
Measure the absorbance values of blank solution, cadmium standard series solution I (5.13) and sample solution in turn, take the cadmium standard series solution I (5.13)
The cadmium concentration is the abscissa, the absorbance value is the ordinate, and the standard curve is drawn, and the correlation coefficient of the standard curve is r≥0.999.Absorbance of sample solution
The degree value should be within the linear range of the standard curve. If it exceeds, it can be appropriately diluted (n times) with reference to the acid concentration of the cadmium standard series solution I (5.13).
post-measurement.
8.3.2 Graphite Furnace Atomic Absorption Spectrometry
Set the instrument to the background button mode, and adjust to the best working state. At the characteristic wavelength of cadmium element at 228.8nm, test according to 10μL
liquid, 5 μL palladium nitrate solution (5.8) and 5 μL ammonium dihydrogen phosphate solution (5.9) (the optimal injection method can be determined according to the instrument used
sample), inject the solution into the graphite furnace, and measure the absorbance values of the blank solution, the cadmium standard series solution II (5.14) and the sample solution in turn.
Taking the cadmium concentration of cadmium standard series solution II (5.14) as the abscissa and the absorbance value as the ordinate, draw a standard curve, and the correlation coefficient of the standard curve
r≥0.995.The absorbance value of the sample solution should be within the linear range of the standard curve.
The acid concentration was determined after appropriate dilution (n-fold).
9 Test data processing
9.1 Flame Atomic Absorption Spectroscopy
The content w of cadmium in the sample is calculated in mass fraction, the unit is milligram per kilogram (mg/kg), and it is calculated according to formula (1).
10 Precision
10.1 Flame Atomic Absorption Spectroscopy
Under repeatability conditions, the ratio d of the absolute difference between the two independent determination results and their arithmetic mean to the arithmetic mean,
Should meet the requirements of Table 4.
10.2 Graphite Furnace Atomic Absorption Spectrometry
Under repeatability conditions, the ratio of the absolute difference between the two independent determination results and their arithmetic mean to the arithmetic mean, d
Should meet the requirements of Table 5.
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