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GB/T 13883-2023: Determination of selenium in feeds
GB/T 13883-2023
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 65.120
CCS B 46
Replacing GB/T 13883-2008
Determination of selenium in feeds
ISSUED ON: AUGUST 06, 2023
IMPLEMENTED ON: MARCH 01, 2024
Issued by: State Administration for Market Regulation;
Standardization Administration of the People's Republic of China.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Terms and definitions ... 4
4 Hydride generation-atomic fluorescence spectrometry (arbitration method) ... 4
5 Fluorescence spectrophotometry ... 9
6 Inductively coupled plasma mass spectrometry ... 13
Annex A (informative) Reference conditions for microwave digestion ... 18
Determination of selenium in feeds
1 Scope
This document describes the determination of selenium in feeds by hydride generation-
atomic fluorescence spectrometry, fluorescence spectrophotometry and inductively
coupled plasma-mass spectrometry.
In this document, hydride generation-atomic fluorescence spectrometry and
fluorescence spectrophotometry are applicable to the determination of selenium in
compound feed, concentrated feed, concentrate supplement, additive premix feed and
feed raw materials. Inductively coupled plasma mass spectrometry is applicable to the
determination of selenium in compound feed, concentrated feed, concentrate
supplement and feed raw materials (except mineral feed raw materials).
When the sample size is 1 g and the fixed volume is 50 mL, the detection limit of
hydride generation-atomic fluorescence spectrometry and fluorescence
spectrophotometry is 0.01 mg/kg and the quantification limit is 0.02 mg/kg. When the
sample size is 0.5 g and the fixed volume is 50 mL, the detection limit of inductively
coupled plasma mass spectrometry is 0.01 mg/kg and the quantification limit is 0.02
mg/kg.
2 Normative references
The following referenced documents are indispensable for the application of this
document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
GB/T 6682, Water for analytical laboratory use - Specification and test methods
GB/T 20195, Animal feed - Preparation of test samples
3 Terms and definitions
There are no terms or definitions that require definition in this document.
4 Hydride generation-atomic fluorescence spectrometry
(arbitration method)
4.1 Principle
After the specimen is digested with acid, the selenium in the specimen digestion
solution is reduced to tetravalent selenium in the hydrochloric acid medium. Potassium
borohydride is used as a reducing agent to reduce tetravalent selenium to hydrogen
selenide in the hydrochloric acid medium. It is carried into the atomizer by the carrier
gas for atomization. Under the irradiation of the selenium hollow cathode lamp, the
ground state selenium atoms are excited to a high energy state. When deactivated and
returned to the ground state, fluorescence of a characteristic wavelength is emitted. Its
fluorescence intensity is proportional to the selenium content and is quantitatively
compared with the standard series.
4.2 Reagents or materials
Warning -- All strong acids shall be handled with caution. Dilution and use shall
be carried out in a fume hood. When using perchloric acid, be careful not to burn
it dry. Be careful of explosion.
Unless otherwise specified, only analytically pure reagents are used.
4.2.1 Water: GB/T 6682, Grade II.
4.2.2 Nitric acid: guaranteed reagent.
4.2.3 Perchloric acid: guaranteed reagent.
4.2.4 Hydrochloric acid: guaranteed reagent.
4.2.5 Sodium hydroxide: guaranteed reagent.
4.2.6 Hydrogen peroxide.
4.2.7 Potassium borohydride: guaranteed reagent.
4.2.8 Mixed acid solution: Measure 400 mL of nitric acid (4.2.2) and mix with 100 mL
of perchloric acid (4.2.3).
4.2.9 Hydrochloric acid solution I: Measure 100 mL of hydrochloric acid (4.2.4) and
mix with 100 mL of water.
4.2.10 Hydrochloric acid solution II: Pipette 5 mL of hydrochloric acid (4.2.4) and mix
with 95 mL of water.
4.2.11 Sodium hydroxide solution (5 g/L): Weigh 5 g of sodium hydroxide. Dissolve it
in water. Set volume to 1000 mL. Mix well.
4.2.12 Potassium borohydride solution (20 g/L): Weigh 20 g of potassium borohydride.
Dissolve it in 1000 mL of sodium hydroxide solution (4.2.11). Mix well.
4.2.13 Potassium ferrocyanide solution (200 g/L): Weigh 20 g of potassium
ferrocyanide. Dissolve it in 100 mL of water. Mix well.
to an accuracy of 0.0001 g. Place in a 100 mL tall beaker. Add 15 mL of mixed acid
solution (4.2.8) (10 mL of additive premix feed) and a few glass beads. Cover with a
watch glass. Leave for more than 12 h. Place on a thermostatically adjustable hot plate
and gradually heat [if the solution becomes darker during heating, remove it. After
cooling to room temperature, add 5 mL of mixed acid solution (4.2.8). Continue
heating]. When a large amount of white smoke is produced on the upper layer of the
solution and the remaining solution volume is about 2 mL, remove it and cool to room
temperature. Add 5 mL of hydrochloric acid solution I (4.2.9). Place on a
thermostatically adjustable electric stove and heat until smoking. The remaining
volume is about 2 mL. Remove it. Cool to room temperature. Transfer to a 50 mL
volumetric flask with water. Add 8 mL of hydrochloric acid (4.2.4) and 2 mL of
potassium ferrocyanide solution (4.2.13). Set to the volume with water. Mix well and
use this as the specimen solution. Perform a blank test at the same time.
4.5.1.2 Microwave digestion
Perform two tests in parallel. Weigh 0.5 g (accurate to 0.000l g) of the specimen into a
polytetrafluoroethylene inner tank. Add 8 mL of nitric acid (4.2.2). Soak for 10 min.
Then add 2 mL of hydrogen peroxide (4.2.6). Let stand for more than 2 h. Cover the
safety valve. Install the protective cover. Place the digestion tank into the microwave
digestion instrument. Set the microwave digestion conditions (see Annex A) and digest
the sample. After the digestion is completed, open the tank cover to vent after cooling
to room temperature. Rinse the inner cover with a small amount of water. Add the
washing liquid to the tank. Place it on an adjustable temperature electric heating plate.
Continue heating at 150℃ until the residual volume is about 2 mL. Remove. Cool. Add
5 mL of hydrochloric acid solution I (4.2.9). Continue heating until the residual volume
is about 2 mL. Remove. Cool to room temperature. Transfer the digestion solution to a
25 mL volumetric flask. Add a small amount of water to wash the digestion tank 4~6
times. Add the washing solution to a volumetric flask. Add 4 mL of hydrochloric acid
(4.2.4) and 1 mL of potassium ferrocyanide solution (4.2.13). Set to the volume with
water. Mix well and use as the specimen solution. Perform a blank test at the same time.
4.5.2 Preparation of standard series solutions
Accurately pipette 0 mL, 0.2 mL, 0.5 mL, 2 mL, 5 mL, 10 mL, 20 mL of selenium
standard intermediate solution II (4.2.16). Place them in 50 mL volumetric flasks,
respectively. Add water to 30 mL. Add 8 mL of hydrochloric acid (4.2.4) and 2 mL of
potassium ferrocyanide solution (4.2.13). Dilute to the mark with water. Mix well.
Prepare a series of selenium standard solutions with mass concentrations of 0 ng/mL,
0.4 ng/mL, 1 ng/mL, 4 ng/mL, 10 ng/mL, 20 ng/mL, and 40 ng/mL. Prepare when
needed.
4.5.3 Instrument reference condit...