GB/T 13082-2021 PDF in English
GB/T 13082-2021 (GB/T13082-2021, GBT 13082-2021, GBT13082-2021)
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| GB/T 13082-2021 | English | 170 |
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Determination of cadmium in feeds
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| GB/T 13082-1991 | English | 70 |
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Method for determination of cadmium in feeds
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Standards related to (historical): GB/T 13082-2021
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GB/T 13082-2021: PDF in English (GBT 13082-2021) GB/T 13082-2021
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 65.120
CCS B 46
Replacing GB/T 13082-1991
Determination of cadmium in feeds
ISSUED ON: NOVEMBER 26, 2021
IMPLEMENTED ON: JUNE 01, 2022
Issued by: State Administration for Market Regulation;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Terms and definitions... 4
4 Principles ... 4
5 Reagents or materials ... 5
6 Instruments and equipment ... 6
7 Samples ... 6
8 Test procedures ... 7
9 Processing of test data ... 10
10 Precision ... 11
Determination of cadmium in feeds
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 determination of cadmium, in compound feeds,
concentrated feeds, concentrate supplements, additive premixed feeds, feed additives,
feed ingredients.
In this document, when the sampling amount is 5 g and the constant volume is 50 mL,
the detection limit of flame atomic absorption spectrometry is 0.08 mg/kg AND the
quantification limit is 0.20 mg/kg. When the sampling amount is 0.5 g and the constant
volume is 25 mL, the detection limit of graphite furnace atomic absorption spectrometry
is 0.002 mg/kg AND the quantification limit is 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, for dated references,
only the version corresponding to the date applies to this document; for undated
references, the latest version (including all amendments) is applicable to this document.
GB/T 6682 Water for analytical laboratory use - Specification and test methods
GB 6819-2004 Dissolved acetylene
GB/T 20195 Animal feeding stuffs - Preparation of test 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 specimen is introduced into the flame or graphite furnace atomizer of
atomic absorption spectrophotometer, to measure the absorbance value at a wavelength
of 228.8 nm. Within a certain concentration range, the cadmium concentration is
proportional to its absorbance value; the standard curve is used for calibration and
quantitative.
5 Reagents or materials
Warning: When using various strong acids, it shall be carried out in a fume hood;
when using perchloric acid for digestion, be careful not to burn it dry, to prevent
explosion.
Unless otherwise specified, only analytical grade reagents are used.
5.1 Water: GB/T 6682, grade 1.
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 (6 mol/L): Dilute 500 mL of hydrochloric acid (5.3) to
1000 mL. Mix well.
5.6 Nitric acid solution: Dilute 10 mL of nitric acid (5.2) to 1000 mL. Mix well.
5.7 Nitric acid solution (6 mol/L): Dilute 43 mL of nitric acid (5.2) to 100 mL. Mix
well.
5.8 Palladium nitrate solution (2 mg/mL): Weigh 0.20 g of palladium nitrate. Use water
to dissolve it. Dilute it to 100 mL. Mix well.
5.9 Ammonium dihydrogen phosphate solution (10 mg/mL): Weigh 1.00 g of
ammonium dihydrogen phosphate. Use water to dissolve it. Dilute it to 100 mL. Mix
well.
5.10 Cadmium standard stock solution (1 mg/mL): Accurately weigh 1.0000 g of metal
cadmium (certified reference material, purity 99.99%), into a 250 mL conical flask. Add
10 mL of nitric acid solution (5.7). Heat on an electric hot plate, to dissolve all. Then,
transfer to a 1000 mL volumetric flask. Add water to the mark. Mix well. Store it in
polyethylene bottles at 4 °C; the validity period is 6 months. OR otherwise 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 nitric acid
solution (5.6), to dilute it to the mark. Mix well. The valid period is 1 month.
5.12 Cadmium standard intermediate solution II (100 μg/L): Accurately pipette 1 mL
of cadmium standard intermediate solution I (5.11), into a 100 mL volumetric flask.
Use nitric acid solution (5.6), to dilute it to the mark. Mix well. Prepare it before use.
8 Test procedures
8.1 Preparation of specimen solution
8.1.1 Dry ashing method
It is suitable for compound feed, concentrated feed, concentrate supplement, pre-mixed
feed containing organic matter additives, feed additives, feed raw materials.
Do two tests in parallel. Weigh 5 g of the specimen (accurate to 0.01 g), in a porcelain
crucible. Place it on an adjustable electric hot plate or an adjustable electric furnace, to
slowly heat and carbonize it, until it is smokeless. Then transfer it to a 500 °C muffle
furnace, for ashing for 5 hours, until the specimen turns white or grey-white, without
carbon particles. If a small amount of carbon particles is found, nitric acid solution (5.7)
can be added to wet the residue. Move the porcelain crucible to an adjustable electric
hot plate or adjustable electric furnace, to dry on a small fire. Then move it into a muffle
furnace, to continue ashing, until the specimen is white or grey-white, without carbon
particles.
Take out the crucible. Cool to room temperature. Absorb 5 mL of hydrochloric acid
solution (5.5). Add it dropwise to the porcelain crucible. Turn it while adding, until no
bubbles overflow from the solution. Add the remaining hydrochloric acid solution.
Then add 5 mL of nitric acid solution (5.7). Move the porcelain crucible to the
adjustable electric heating plate or adjustable electric furnace. Slowly heat it, until the
digestion solution reaches 2 mL ~ 3 mL (be careful to prevent splashing). Remove it.
Cool it to room temperature. Transfer the digestion solution into a 50 mL volumetric
flask. Use a small volume of water, to rinse the wall of the porcelain crucible several
times. Incorporate it into the volumetric flask. Add water to the mark. Shake well. Filter
it. Prepare for use. At the same time, do a blank test.
8.1.2 Wet digestion method
It is suitable for additive premixed feed which contain more organic matter, feed
additives, feed raw materials.
Do two tests in parallel. Weigh 1 g of the specimen (accurate to 0.0001 g) into the
digestion tube. Add a small amount of water to wet it. Add 10 mL of nitric acid (5.2).
Put it in a fume hood. Let it stand for 2 hours. Then add 5 mL of perchloric acid (5.4).
Use small fire, to heat it on an adjustable electric heating plate or an adjustable electric
furnace, which is below 250 °C, for digestion, until the digestion solution emits white
smoke. Remove it and cool it. Transfer the digestion solution into a 50 mL volumetric
flask. Use a small volume of water, to rinse the digestion tube several times. Incorporate
it into the volumetric flask. Add water to the mark. Shake well. Filter it. Prepare for use.
At the same time, do a blank test.
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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