GB/T 13079-2022_English: PDF (GB/T13079-2022)
| Standard ID | Contents [version] | USD | STEP2 | [PDF] delivered in | Standard Title (Description) | Status | PDF |
| GB/T 13079-2022 | English | 215 |
Add to Cart
|
0--9 seconds. Auto-delivery
|
Determination of total arsenic in feeds
| Valid |
GB/T 13079-2022
|
| GB/T 13079-2006 | English | 230 |
Add to Cart
|
0--9 seconds. Auto-delivery
|
Determination of total arsenic in feeds
| Obsolete |
GB/T 13079-2006
|
| GB/T 13079-1999 | English | 359 |
Add to Cart
|
3 days [Need to translate]
|
Determination of total arsenic in feeds
| Obsolete |
GB/T 13079-1999
|
| GB/T 13079-1991 | English | RFQ |
ASK
|
3 days [Need to translate]
|
Method for determination of total arsenic in feeds
| Obsolete |
GB/T 13079-1991
|
| Standard ID | GB/T 13079-2022 (GB/T13079-2022) | | Description (Translated English) | Determination of total arsenic in feeds | | Sector / Industry | National Standard (Recommended) | | Classification of Chinese Standard | B46 | | Classification of International Standard | 65.120 | | Word Count Estimation | 18,165 | | Date of Issue | 2022-12-30 | | Date of Implementation | 2023-07-01 | | Older Standard (superseded by this standard) | GB/T 13079-2006 | | Drafting Organization | Sichuan Weier Testing Technology Co., Ltd., Shaanxi Provincial Animal Husbandry Technology Promotion Station, Shaanxi Qinyun Agricultural Products Inspection and Testing Co., Ltd. | | Administrative Organization | National Feed Industry Standardization Technical Committee (SAC/TC 76) | | Proposing organization | State Administration for Market Regulation, National Standardization Management Committee | | Standard ID | GB/T 13079-2006 (GB/T13079-2006) | | Description (Translated English) | Determination of total arsenic in feeds | | Sector / Industry | National Standard (Recommended) | | Classification of Chinese Standard | B46 | | Classification of International Standard | 65.120 | | Word Count Estimation | 10,190 | | Date of Issue | 2006-12-12 | | Date of Implementation | 2007-03-01 | | Older Standard (superseded by this standard) | GB/T 13079-1999 | | Quoted Standard | GB/T 6682; GB/T 14699.1; GB/T 20195 | | Drafting Organization | National Feed Quality Supervision and Inspection Center (Beijing) | | Administrative Organization | National Standardization Technical Committee Feed Industry | | Regulation (derived from) | National Standard Approval Announcement 2006 No.13 (Total No.100) | | Proposing organization | People's Republic of China Ministry of Agriculture | | Issuing agency(ies) | Administration of Quality Supervision, Inspection and Quarantine of People's Republic of China; Standardization Administration of China | | Summary | This standard specifies the method for the determination of total arsenic in feed. This standard applies to all kinds of feed, concentrated feed, additive premix feed, single feed and feed additives. | | Standard ID | GB/T 13079-1999 (GB/T13079-1999) | | Description (Translated English) | Determination of total arsenic in feeds | | Sector / Industry | National Standard (Recommended) | | Classification of Chinese Standard | B46 | | Classification of International Standard | 65.120. | | Word Count Estimation | 9,954 | | Date of Issue | 1999/8/10 | | Date of Implementation | 2000/2/1 | | Older Standard (superseded by this standard) | GB/T 13079-1991 | | Adopted Standard | ISO 2590-1973, NEQ | | Regulation (derived from) | Announcement of Newly Approved National Standards No. 13, 2006 (No. 100 overall) | | Proposing organization | Ministry of Machinery and Electronics Industry and Materials Department | | Issuing agency(ies) | State Quality and Technical Supervision |
GB/T 13079-2022
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 65.120
CCS B 46
Replacing GB/T 13079-2006
Determination of Total Arsenic in Feeds
ISSUED ON: DECEMBER 30, 2022
IMPLEMENTED ON: JULY 1, 2023
Issued by: State Administration for Market Regulation;
Standardization Administration of the People’s Republic of China.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative References ... 5
3 Terms and Definitions ... 5
4 Silver Salt Method (arbitration method) ... 5
5 Hydride Generation-atomic Fluorescence Spectrometry ... 12
6 Inductively Coupled Plasma Mass Spectrometry ... 18
Appendix A (informative) Microwave Digestion Reference Conditions ... 23
Determination of Total Arsenic in Feeds
1 Scope
This document describes the silver salt method, hydride generation-atomic fluorescence
spectrometry and inductively coupled plasma mass spectrometry for the determination of total
arsenic in feeds.
This document is applicable to the determination of total arsenic in compound feeds,
concentrated feeds, concentrate supplements, additive premixed feeds, feedstuffs and feed
additives.
When the sampling size is 5 g and the constant volume is 50 mL, the detection limit of the silver
salt method is 0.25 mg/kg and the quantitation limit is 0.50 mg/kg; when the sampling size is 5
g, the constant volume is 50 mL and the dilution factor is 20, the detection limit of the hydride
generation-atomic fluorescence spectrometry and inductively coupled plasma mass
spectrometry is 0.02 mg/kg, and the quantitation limit is 0.05 mg/kg.
2 Normative References
The contents of the following documents constitute indispensable clauses of this document
through the normative references in the text. In terms of references with a specified date, only
versions with a specified date are applicable to this document. In terms of references without a
specified date, the latest version (including all the modifications) is applicable to this document.
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
This document does not have terms or definitions that need to be defined.
4 Silver Salt Method (arbitration method)
4.1 Principle
After a specimen is treated by acid digestion, direct acid dissolution or dry ashing method, use
potassium iodide and stannous chloride to reduce high-valent arsenic to trivalent arsenic, then,
generate arsine with the new ecological hydrogen produced by zinc particles and acid, which is
absorbed by the silver diethyldithiocarbamate (Ag-DDTC)-triethylamine-chloroform solution
to form a red jelly, whose color shade is proportional to the arsenic content. Use a
spectrophotometer to determine the absorbance and quantitatively compare it with standard
series of solutions.
4.2 Reagents or Materials
WARNING---handle all kinds of strong acids with caution. Dilute and use them in a fume
hood. When using perchloric acid, be careful not to burn it to dryness, and be careful of
explosion.
Unless otherwise specified, use only analytically pure reagents.
4.2.1 Water: GB/T 6682, Grade-2.
4.2.2 Nitric acid.
4.2.3 Hydrochloric acid.
4.2.4 Chloroform.
4.2.5 Magnesium oxide.
4.2.6 Magnesium nitrate.
4.2.7 L-ascorbic acid.
4.2.8 Arsenic-free zinc particles: with a particle size of 3.0 mm 0.2 mm.
4.2.9 Mixed acid solution: nitric acid + perchloric acid + sulfuric acid = 230 + 50 + 30. Mix it
well and store it in a brown reagent bottle.
4.2.10 Hydrochloric acid solution (6 mol/L): measure-take 250 mL of hydrochloric acid (4.2.3),
add 250 mL of water and mix it well.
4.2.11 Magnesium nitrate solution: weigh-take 180 g of magnesium nitrate [Mg (NO3)2 6H2O],
add water to dissolve it, dilute and reach a constant volume of 1,000 mL, and mix it well.
4.2.12 Potassium iodide solution (150 g/L): weigh-take 75 g of potassium iodide, add water to
dissolve it, dilute to 500 mL, mix it well, and store in a brown bottle.
4.2.13 Acidic stannous chloride solution: weigh-take 40 g of stannous chloride (SnCl2 2H2O),
use 100 mL of hydrochloric acid (4.2.3) to dissolve it, then, add a few tin particles, and store in
a brown reagent bottle. The shelf life is 1 week.
4.2.14 Silver diethyldithiocarbamate (Ag-DDTC)-triethylamine-chloroform solution (2.5 g/L):
weigh-take 2.5 g (accurate to 0.0001 g) of Ag-DDTC in a dry beaker, add an appropriate amount
of chloroform. After it is completely dissolved, add 20 mL of triethylamine, use chloroform to
transfer it to a 1,000 mL volumetric flask, reach a constant volume and mix it well; store it in a
brown reagent bottle and in the dark at 2 C ~ 8 C. If there is precipitation, it shall be filtered
before use.
4.2.15 Lead acetate solution (200 g/L): weigh-take 40 g of lead acetate, add water to dissolve
it, dilute to 200 mL and mix it well.
4.2.16 Lead acetate cotton: soak the medical absorbent cotton in the lead acetate solution (4.2.15)
for 1 hour, squeeze out the excess lead acetate solution, make it loose, and naturally dry it, or
dry it at 90 C ~ 100 C, and store in an airtight bottle.
4.2.17 Sodium hydroxide solution (200 g/L): weigh-take 200 g of sodium hydroxide, add 500
mL of water to dissolve it, then, use water to dilute to 1,000 mL and mix it well.
4.2.18 Sulfuric acid solution (6%): measure-take 60 mL of sulfuric acid, slowly add 500 mL of
water. After cooling, use water to dilute to 1,000 mL, and mix it well.
4.2.19 Arsenic standard stock solution (0.1 mg/mL, calculated by arsenic): accurately weigh-
take 0.1320 g (accurate to 0.0001 g) of arsenic trioxide (CAS: 1327-53-3, purity 99.5%) that
has been dried at 100 C for 2 hours, and add 5 mL of sodium hydroxide solution (4.2.17) to
dissolve it, then, add 25 mL of sulfuric acid solution (4.2.18) and transfer to a 1,000 mL
volumetric flask. Use newly boiled and cooled water to reach a constant volume and mix it well.
Store it in a plastic bottle and in the dark at 2 C ~ 8 C. The shelf life is 12 months. Alternatively,
purchase certified reference material of arsenic.
4.2.20 Arsenic standard intermediate solution (1 g/mL): accurately transfer-take 1 mL of
arsenic standard stock solution (4.2.19) into a 100 mL volumetric flask, add 1 mL of
hydrochloric acid solution (4.2.10), use water to reach a constant volume and mix it well. Store
it in a plastic bottle and in the dark at 2 C ~ 8 C. The shelf life is 1 month.
4.3 Instruments and Equipment
4.3.1 Spectrophotometer: with a wavelength accuracy of 2 nm.
4.3.2 Analytical balance: with an accuracy of 0.0001 g.
4.3.3 Electric drying oven: with a temperature control accuracy of 5 C.
4.3.4 Temperature controllable electric heating plate: with a temperature control accuracy of
5 C.
4.3.5 Muffle furnace: with a temperature control accuracy of 15 C.
4.3.6 Graphite digestion instrument: equipped with matching polytetrafluoroethylene digestion
tube.
4.3.7 Arsine generation and absorption device (see Figure 1): consists of a 125 mL arsenic
reaction bottle with graduations, a 5 mL arsenic absorption tube, and an air guide tube
connecting the arsenic reaction bottle and the arsenic absorption tube. The arsenic reaction
bottle, air guide tube and arsenic absorption tube are connected with ground joints to ensure no
air leakage.
4.5.1 Preparation of specimen solution
4.5.1.1 Mixed acid digestion method
Carry out two tests in parallel. Respectively weigh-take 3 g ~ 5 g of compound feed, concentrate
supplement, and animal and vegetable feedstuff; respectively weigh-take 2 g ~ 3 g of
concentrated feed, additive premixed feed containing organic matter, feed additive and
attapulgite powder specimen, accurate to 0.001 g. Place it in a 250 mL conical flask, add a small
amount of water to moisten the specimen, add 25 mL of mixed acid solution (4.2.9), mix it well,
then, cover the funnel and let it stand overnight. Remove the funnel, transfer it to an adjustable
electric furnace and heat it for digestion at 150 C. After the brown gas disappears and the
solution becomes clear, raise the temperature to 200 C and continue digestion, until the smoke
of perchloric acid dissipates and the white smoke of sulfuric acid beings to emerge. Immediately
take it off and cool it. If there are still undecomposed substances or if the color is relatively
dark, add 5 mL ~ 10 mL of nitric acid (4.2.2), continue heating and digestion, and repeat 2 ~ 3
times. Be careful to avoid carbonization, until the specimen is completely digested. Add 25 mL
of water, then evaporate it, until the sulfuric acid emits white smoke. Remove it, cool it to room
temperature, and use water to transfer to a 50 mL volumetric flask. Use a small amount of water
to rinse the conical flask for 3 ~ 5 times, merge the washing liquid into the volumetric flask,
reach a constant volume, mix it well and filter it. The filtrate is the specimen solution.
Meanwhile, carry out a blank test.
4.5.1.2 Dry ashing method
4.5.1.2.1 Compound feeds, concentrated feeds, concentrate supplements, animal and
vegetable feedstuffs (except marine feedstuff), additive premixed feeds containing organic
matter and feed additives
Carry out two tests in parallel. Respectively weigh-take 3 g ~ 5 g of compound feed, concentrate
supplement, and animal and vegetable feedstuff (except marine feedstuff); respectively weigh-
take 2 g ~ 3 g of concentrated feed, additive premixed feed containing organic matter and feed
additive specimen, accurate to 0.001 g. Place it in a 50 mL porcelain crucible, add 10 mL of
magnesium nitrate solution (4.2.11) and 1 g of magnesium oxide (4.2.5), mix it well and soak
for 4 hours. After evaporating it to dryness at low temperature on an electric heating plate at
100 C (or drying in an electric drying oven at 105 C), transfer it to an electric furnace to
carbonize, until it becomes smokeless, then, transfer to a muffle furnace at 550 C and ash for
4 hours. Take it out, cool to room temperature, slowly add 10 mL of hydrochloric acid solution
(4.2.10), and heat and dissolve it, until the solution becomes clear. Then, transfer it to a 50 mL
volumetric flask, use a small amount of water to rinse the crucible 3 ~ 5 times, and merge the
washing liquid into the volumetric flask. Reach a constant volume, shake it well, and filter it.
The filtrate is the specimen solution. Meanwhile, carry out a blank test.
4.5.1.2.2 Animal and vegetable oil feedstuffs
Carry out two tests in parallel. Weigh-take 5 g of animal and vegetable oil feedstuff specimen
(accurate to 0.001 g), place it in a 50 mL porcelain crucible, add 10 g of magnesium nitrate
(4.2.6), 2 g of magnesium oxide (4.2.5), mix it well, and transfer onto an electric furnace, and
heat it over low heat, until it emits smoke. Immediately remove the crucible to prevent the
contents from overflowing. After the oily fume dissipates, then carbonize it, until it becomes
smokeless. Then, transfer to a 550 C muffle furnace for ashing for 4 hours. Take it out and
cool, and slowly add 10 mL of hydrochloric acid solution (4.2.10). Heat and dissolve it, until
the solution becomes clear. Then, transfer to a 50 mL volumetric flask, use a small amount of
water to rinse the crucible 3 ~ 5 times, merge the washing liquid into the volumetric flask.
Reach a constant volume, mix it well and filter it. The filtrate is the specimen solution.
Meanwhile, carry out a blank test.
4.5.1.3 Direct acid dissolution method
Carry out two tests in parallel. Respectively weigh-take 1 g ~ 3 g of mineral feedstuff, trace
element premixed feed without organic matter, and mineral element feed additive specimen
without complexes (chelates), accurate to 0.0001 g, place into 150 mL conical flask, and slowly
add 10 mL of hydrochloric acid solution (4.2.10) and 1 mL of nitric acid (4.2.2) to dissolve it.
After the reaction, transfer it to an electric stove or electric heating plate for heating and
digestion. When the solution becomes clear and has a volume of about 5 mL, remove it, cool to
room temperature, transfer to a 50 mL volumetric flask, and use a small amount of water to
rinse the conical flask for 3 ~ 5 times. Merge the washing liquid into the volumetric flask, reach
a constant volume, shake it well and filter it. The filtrate is the specimen solution. Meanwhile,
carry out a blank test.
4.5.2 Determination
4.5.2.1 Preparation of standard series of solutions
Accurately transfer-take 0.00 mL, 1.00 mL, 2.00 mL, 4.00 mL, 6.00 mL, 8.00 mL and 10.00
mL of the arsenic standard intermediate solution (4.2.20), respectively place them in arsenic
reaction bottle, and use water to dilute to 30 mL. Add 10 mL of hydrochloric acid (4.2.3), mix
it well, and follow the steps specified in 4.5.2.2, starting from the addition of 2 mL of potassium
iodide solution (4.2.12).
4.5.2.2 Reduction reaction
In accordance with the total arsenic content in the specimen, accurately transfer-take 2 mL ~ 20
mL of specimen solution (4.5.1) into the arsenic reaction bottle, add hydrochloric acid (4.2.3)
to a total volume of 10 mL, and use water to dilute to 40 mL, so that the hydrochloric acid
concentration of the solution is 3 mol/L, then, respectively add 2 mL of potassium iodide
solution (4.2.12) to the specimen solution, blank solution and the standard series of solutions,
mix well. Add 1 mL of acidic stannous chloride solution (4.2.13), 0.2 g of L-ascorbic acid (4.2.7)
and mix it well. Let it stand for 15 minutes of the reduction reaction, and reserve it for testing.
Accurately transfer-take 5 mL of silver diethyldithiocarbamate (Ag-DDTC)-triethylamine-
chloroform solution (4.2.14) into the arsenic absorption tube, insert the tip of the air guide tube
of the reaction device [the expanded part of the tube is stuffed with fluffy lead acetate cotton
(4.2.16)] into the arsenic absorption tube, and quickly add 4 g of arsenic-free zinc particles
5.2.7 Magnesium nitrate.
5.2.8 Potassium hydroxide: guaranteed reagent.
5.2.9 Potassium borohydride: guaranteed reagent.
5.2.10 Mixed acid solution: nitric acid (5.2.2) + perchloric acid + sulfuric acid (5.2.4) = 230 +
50 + 30, mix well and store in a brown reagent bottle.
5.2.11 Hydrochloric acid solution (6 mol/L): measure-take 250 mL of hydrochloric acid (5.2.3)
and 250 mL of water, and evenly mix it.
5.2.12 Potassium hydroxide solution (8 g/L): weigh-take 8 g of potassium hydroxide (5.2.8),
add water to dissolve it, dilute and reach a constant volume of 1,000 mL, and mix it well.
Prepare it right before use.
5.2.13 Potassium borohydride solution (20 g/L): weigh-take 20 g of potassium borohydride
(5.2.9), dissolve it in 1,000 mL of potassium hydroxide solution (5.2.12), and mix it well.
Prepare it right before use.
5.2.14 Magnesium nitrate solution (180 g/L): weigh-take 180 g of magnesium nitrate [Mg
(NO3)2 6H2O], add water to dissolve it, dilute and reach a constant volume of 1,000 mL, and
mix it well.
5.2.15 Thiourea-ascorbic acid solution (100 g/L): weigh-take 100 g of thiourea and 100 g of L-
ascorbic acid, add water to dissolve it, reach a constant volume of 1,000 mL and mix it well.
Prepare it right before use.
5.2.16 Ammonium thiocyanate-hydroxylamine hydrochloride solution (100 g/L): weigh-take
100 g of ammonium thiocyanate and 100 g of hydroxylamine hydrochloride, add water to
dissolve it, reach a constant volume of 1,000 mL and mix it well. Prepare it right before use.
5.2.17 Sodium hydroxide solution (200 g/L): weigh-take 200 g of sodium hydroxide, add water
to dissolve it, reach a constant volume of 1,000 mL and mix it well.
5.2.18 Sulfuric acid solution (6%): measure-take 60 mL of sulfuric acid (5.2.4), slowly add it
to 500 mL of water. After cooling, use water to dilute to 1,000 mL and mix it well.
5.2.19 Arsenic standard stock solution (0.1 mg/mL): accurately weigh-take 0.1320 g (accurate
to 0.0001 g) of arsenic trioxide (CAS: 1327-53-3, purity 99.5%) that has been dried at 100
C for 2 hours, and add 5 mL of sodium hydroxide solution (5.2.17) to dissolve it, then, add 25
mL of sulfuric acid solution (5.2.18) and transfer to a 1,000 mL volumetric flask. Use newly
boiled and cooled water to reach a constant volume and mix it well. Store it in a plastic bottle
and in the dark at 2 C ~ 8 C. The shelf life is 12 months. Alternatively, purchase certified
reference material of arsenic.
5.2.20 Arsenic standard intermediate solution (1 g/mL): accurately transfer-take 1 mL of
arsenic standard stock solution (5.2.19) into a 100 mL volumetric flask, add 1 mL of
hydrochloric acid solution (5.2.11), use water to reach a constant volume and mix it well. Store
it in a plastic bottle and in the dark at 2 C ~ 8 C. The shelf life is 1 month.
5.2.21 Arsenic standard working solution (100 ng/mL): accurately transfer-take 10 mL of
arsenic standard intermediate solution (5.2.20) into a 100 mL volumetric flask, add 1 mL of
hydrochloric acid solution (5.2.11), use water to dilute it and reach a constant volume, and mix
it well. The shelf life is 1 week.
5.3 Instruments and Equipment
5.3.1 Atomic fluorescence spectrophotometer.
5.3.2 Analytical balance: with an accuracy of 0.0001 g.
5.3.3 Muffle furnace: with a temperature control accuracy of 15 C.
5.3.4 Electric drying oven: with a temperature control accuracy of 5 C.
5.3.5 Adjustable electric furnace.
5.3.6 Graphite digestion instrument: equipped with matching polytetrafluoroethylene digestion
tube.
5.3.7 Microwave digestion instrument: equipped with matching polytetrafluoroethylene
digestion tube.
5.3.8 High-pressure digestion tank: equipped with matching polytetrafluoroethylene digestion
inner tube.
5.3.9 Acid flushing instrument: with a temperature control accuracy of 2 C.
5.4 Sample
Same as 4.4.
5.5 Test Procedures
5.5.1 Preparation of specimen solution
WARNING---when using microwave digestion instrument and high-pressure digestion
tube to digest samples, strong acid, high temperature and high pressure may easily cause
unsafe incidents. Operators shall rigorously follow the instrument operation instructions
in accordance with the type of samples to ensure personal and laboratory safety.
5.5.1.1 Mixed acid digestion method
Same as 4.5.1.1.
5.5.1.2 Dry ashing method
water to transfer it to a 50 mL volumetric flask, and use a small amount of water to rinse the
conical flask for 3 times. Merge the washing liquid into the volumetric flask, reach a constant
volume, shake it well and filter it. The filtrate is the specimen solution. Meanwhile, carry out a
blank test.
Carry out two tests in parallel. Respectively weigh-take 2 g ~ 3 g (accurate to 0.001 g) of
additive premixed feed and feed additive specimen with copper sulfate, basic copper chloride
and copper content exceeding 0.8%, and place in a 150 mL conical flask. Slowly add 10 mL of
hydrochloric acid solution (5.2.11) and 1 mL of nitric acid (5.2.2). After the reaction, transfer it
to an electric stove or electric heating plate for heating and digestion. When the solution reaches
about 5 mL, remove it and cool to room temperature. Use water to transfer it to a 50 mL
volumetric flask, add 10 mL of ammonium thiocyanate-hydroxylamine hydrochloride (5.2.16),
and use a small amount of water to rinse the conical flask for 3 ~ 5 times. Merge the washing
liquid into the volumetric flask, reach a constant volume, mix it well, let it stand for 30 minutes
and filter it. Take the filtrate as the specimen solution. Meanwhile, carry out a blank test.
5.5.2 Preparation of arsenic standard series of solutions
Respectively and accurately transfer-take an appropriate volume or arsenic standard working
solution (5.2.21) into a 50 mL volumetric flask, add water to about 40 mL, add 2.5 mL of
hydrochloric acid (5.2.3) and mix it well. Slowly add 5 mL of thiourea-ascorbic acid solution
(5.2.15), add water to dilute to a constant volume and mix it well. Thus, the arsenic standard
series of solutions respectively with a concentration of 0 ng/mL, 0.50 ng/mL, 1.00 ng/mL, 4.00
ng/mL, 8.00 ng/mL and 16.00 ng/mL are prepared.
5.5.3 Reduction reaction
In accordance with the total arsenic content in the specimen, accurately transfer-take 5 mL ~ 20
mL of specimen solution (5.5.1) into a 50 mL volumetric flask, add water to about 40 mL, then,
add 2.5 mL of hydrochloric acid (5.2.3) and mix it well. Slowly add 5 mL of thiourea-ascorbic
acid solution (5.2.15), add water to reach a constant volume, and mix it well. After simultaneous
reduction reaction with the arsenic standard series of solutions for 30 minutes, reserve it for
testing.
5.5.4 Instrument reference conditions
The instrument reference conditions are as follows:
a) Negative high voltage: 200 V ~ 400 V;
b) Arsenic hollow cathode lamp current: 15 mA ~ 100 mA;
c) Atomizer temperature: 200 C;
d) Atomizer height: 8 mm;
e) Carrier gas flow: 600 mL/min;
6.2.8 Hydrochloric acid solution (6 mol/L): measure-take 250 mL of hydrochloric acid (6.2.3)
and 250 mL of water, and evenly mix it.
6.2.9 Magnesium nitrate solution (180 g/L): weigh-take 180 g of magnesium nitrate [Mg (NO3)2
6H2O], add water to dissolve it, dilute and reach a constant volume of 1,000 mL, and mix it
well.
6.2.10 Ammonium thiocyanate-hydroxylamine hydrochloride solution (100 g/L): weigh-take
100 g of ammonium thiocyanate and 100 g of hydroxylamine hydrochloride, add water to
dissolve it, reach a constant volume of 1,000 mL and mix it well. Prepare it right before use.
6.2.11 Nitric acid solution (5%): measure-take 50 mL of nitric acid (6.2.2), slowly add it to an
appropriate amount of water, use water to reach a constant volume of 1,000 mL and mix it well.
6.2.12 Sodium hydroxide solution (200 g/L): weigh-take 200 g of sodium hydroxide, add water
to dissolve it, reach a constant volume of 1,000 mL and mix it well.
6.2.13 Sulfuric acid solution (6%): measure-take 60 mL of sulfuric acid (6.2.4), slowly add it
to 500 mL of water. After cooling, use water to dilute to 1,000 mL and mix it well.
6.2.14 Arsenic standard stock solution (0.1 mg/mL): accurately weigh-take 0.1320 g (accurate
to 0.0001 g) of arsenic trioxide (CAS: 1327-53-3, purity 99.5%) that has been dried at 100
C for 2 hours, and add 5 mL of sodium hydroxide solution (6.2.12) to dissolve it, then, add 25
mL of sulfuric acid solution (6.2.13) and transfer to a 1,000 mL volumetric flask. Use newly
boiled and cooled water to reach a constant volume and mix it well. Store it in a plastic bottle
and in the dark at 2 C ~ 8 C. The shelf life is 12 months. Alternatively, purchase certified
reference material of arsenic.
6.2.15 Arsenic standard intermediate solution (1 g/mL): accurately transfer-take 1 mL of
arsenic standard stock solution (6.2.14) into a 100 mL volumetric flask, add 1 mL of
hydrochloric acid solution (6.2.8), use water to reach a constant volume and mix it well. Store
it in a plastic bottle and in the dark at 2 C ~ 8 C. The shelf life is 1 month.
6.2.16 Arsenic standard working solution (100 ng/mL): accurately transfer-take 10 mL of
arsenic standard intermediate solution (6.2.15) into a 100 mL volumetric flask, add 1 mL of
hydrochloric acid solution (6.2.8), use water to dilute it and reach a constant volume, and mix
it well. The shelf life is 1 week.
6.2.17 Internal standard working solution: transfer-take an appropriate amount of germanium
(72Ge) standard solution, use nitric acid solution (6.2.11) to dilute it to 100 ng/mL. The shelf
life is 3 months.
6.2.18 Arsenic standard series of solutions: accurately transfer-take an appropriate amount of
arsenic standard working solution (6.2.16), use nitric acid solution (6.2.11) to respectively
prepare arsenic concentrations of 0.0 ng/mL, 5.0 ng/mL, 10.0 ng/mL, 20.0 ng/mL, 25.0 ng/mL
and 50.0 ng/mL, mix them well. Prepare them right before use.
6.2.19 Argon gas: with a purity 99.999%.
6.3 Instruments and Equipment
6.3.1 Inductively coupled plasma mass spectrometer.
6.3.2 Analytical balance: with an accuracy of 0.0001 g.
6.3.3 Muffle furnace: with a temperature control accuracy of 15 C.
6.3.4 Electric drying oven: with a temperature control accuracy of 5 C.
6.3.5 Adjustable electric furnace.
6.3.6 Graphite digestion instrument: equipped with matching polytetrafluoroethylene digestion
tube.
6.3.7 Microwave digestion instrument: equipped with matching polytetrafluoroethylene
digestion tube.
6.3.8 High-pressure digestion tank: equipped with matching polytetrafluoroethylene digestion
inner tube.
6.3.9 Acid flushing instrument: with a temperature control accuracy of 2 C.
6.3.10 Temperature controllable electric heating plate: with a temperature control accuracy of
5 C.
6.4 Sample
Same as 4.4.
6.5 Test Procedures
6.5.1 Preparation of specimen solution
6.5.1.1 Dry ashing method
Same as 4.5.1.2.
6.5.1.2 Microwave digestion method
Same as 5.5.1.3.
6.5.1.3 High-pressure tank digestion method
Same as 5.5.1.4.
6.5.1.4 Direct acid dissolution method
......
GB/T 13079-2006
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 65.120
B 46
Replacing GB/T 13079-1999
Determination of total arsenic in feeds
ISSUED ON: DECEMBER 12, 2006
IMPLEMENTED ON: MARCH 01, 2007
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine of PRC;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Sampling ... 4
4 Specimen preparation ... 4
5 Silver salt method (arbitration method) ... 4
6 Borohydride reduction spectrophotometry (fast method) ... 11
7 Hydride atomic fluorescence spectrometry (fast method) ... 14
Determination of total arsenic in feeds
1 Scope
This standard specifies the method for the determination of total arsenic in feeds.
This standard is applicable to various compound feeds, concentrated feeds, premixed
feeds with additives, single feeds, feed additives.
Minimum detectable concentration: The silver salt method is 0.04 mg/kg; borohydride
reduction spectrophotometry is 0.04 mg/kg; atomic fluorescence spectrometry is 0.010
mg/kg.
2 Normative references
The provisions in following documents become the provisions of this Standard through
reference in this Standard. For the dated references, the subsequent amendments
(excluding corrections) or revisions do not apply to this Standard; however, parties who
reach an agreement based on this Standard are encouraged to study if the latest versions
of these documents are applicable. For undated references, the latest edition of the
referenced document applies.
GB/T 6682 Water for analytical laboratory use - Specification and test methods
GB/T 14699.1 Feeding Stuffs - Sampling
GB/T 20195 Animal feeding stuffs - Preparation of test samples
3 Sampling
It is carried out, according to GB/T 14699.1.
4 Specimen preparation
It is carried out, according to GB/T 20195.
5 Silver salt method (arbitration method)
5.1 Principle
The sample is subject to acid digestion or dry ashing, to destroy the organic matter, so
that the arsenic exists in ion state. The high-valent arsenic is reduced to trivalent arsenic,
by potassium iodide and stannous chloride, then reduced to arsine hydrogen, by the new
ecological hydrogen, which is produced by zinc particles and acid. In a closed device,
it is absorbed by a chloroform solution of silver diethyldithiocarbamate (Ag-DDTC), to
form a yellow or brown-red silver sol, the color depth of which is proportional to the
arsenic content. It is measured by a spectrophotometer. The reaction to form colloidal
silver is as follows:
5.2 Reagents and solutions
Unless otherwise specified, the following reagents are analytically pure; the water shall
meet the requirements for grade-2 water in GB/T 6682.
5.2.1 Nitric acid.
5.2.2 Sulfuric acid.
5.2.3 Perchloric acid.
5.2.4 Hydrochloric acid.
5.2.5 Acetic acid.
5.2.6 Potassium iodide.
5.2.7 L-Ascorbic acid.
5.2.8 Arsenic-free zinc particles, which has a particle size of 3.0 mm ± 0.2 mm.
5.2.9 Mixed acid solution (A): HNO3 + H2SO4 + HClO4 = 23 + 3 + 4.
5.2.10 Hydrochloric acid solution: c(HCl) = 1 mol/L.
Measure 84.0 mL of hydrochloric acid (5.2.4). Pour it into an appropriate amount of
water. Use water to dilute it to 1 L.
5.2.11 Hydrochloric acid solution: c(HCl) = 3 mol/L.
Measure 250.0 mL of hydrochloric acid (5.2.4). Pour into an appropriate amount of
water. Use water to dilute it to 1 L.
5.2.12 Lead acetate solution: 200 g/L.
5.2.13 Magnesium nitrate solution: 150 g/L.
Weigh 30 g of magnesium nitrate [Mg(NO3)2 • 6H2O]. Dissolve it in water. Dilute to
200 mL.
5.2.14 Potassium iodide solution: 150 g/L.
Weigh 75 g of potassium iodide. Dissolve it in water. Make the volume reach to 500
mL. Store it in a brown bottle.
5.2.15 Acidic stannous chloride solution: 400 g/L.
Weigh 20 g of stannous chloride (SnCl2 • 2H2O). Dissolve it in 50 mL of hydrochloric
acid. Add a few metal tin particles. It can be used for one week.
5.2.16 Silver diethyldithiocarbamate (Ag-DDTC)-triethylamine-chloroform absorption
solution: 2.5 g/L.
Weigh 2.5 g (accurate to 0.0001 g) of Ag-DDTC in a dry beaker. Add an appropriate
amount of chloroform to dissolve completely. Then transfer to a 1000 mL volumetric
flask. Add 20 mL of triethylamine. Use chloroform to make the volume reach to the
mark. Store it in a brown bottle in a cool dark place. If there is precipitation, it shall be
filtered before use.
5.2.17 Lead acetate cotton: Soak medical absorbent cotton in lead acetate solution (100
g/L) for about 1 hour, to press off the excess solution. Dry it naturally. OR dry it at
90 °C ~ 100 °C. Store it in an airtight bottle.
5.2.18 Arsenic standard stock solution 1.0 mg/mL.
Accurately weigh 0.660 g of arsenic trichloride (110 °C, dry for 2 h). Add 5 mL of
sodium hydroxide solution (5.2.21), to dissolve it. Then add 25 mL of sulfuric acid
solution (5.2.20), for neutralization. Make the volume reach to 500 mL. Each millimeter
of this solution contains 1.00 mg of arsenic. Store it in a plastic bottle, in a cold place.
5.2.19 Arsenic standard working solution: 1.0 μg/mL.
Accurately pipette 5.00 mL of arsenic standard stock solution (5.2.18), into a 100 mL
volumetric flask. Add water to make the volume reach to the mark. This solution
contains 50 μg/mL arsenic.
Accurately pipette 2.00 mL of 50 μg/mL arsenic standard solution. Add 1 mL of
hydrochloric acid, into a 100 mL volumetric flask. Add water to make the volume reach
to the mark. Shake well. Each millimeter of this solution is equivalent to 1.0 μg of
arsenic.
5.2.20 Sulfuric acid solution: 60 mL/L.
Pipette 6.0 mL of sulfuric acid. Slowly add it to about 80 mL of water. Use water to
dilute to 100 mL, after cooling.
5.4.1 Handling of samples
5.4.1.1 Mixed acid digestion method
Compound feed and single feed should be digested by nitric acid-sulfuric acid-
perchloric acid. Weigh 3 g ~ 4 g of the sample (accurate to 0.0001 g). Place it in a 250
mL Kjeldahl bottle. Add a little water to wet the specimen. Add 30 mL of mixed acid
solution (A) (5.2.9). Place it for more than 4 h or overnight. Put it on the electric stove,
to start to digest from room temperature. After the brown gas disappears, increase the
digestion temperature, until white smoke (SO3) is emitted for a few minutes (be sure to
drive off the nitric acid). At this time, the solution shall be clear and colorless or light
yellow. The volume of the solution in the bottle is similar to the consumption of sulfuric
acid. The residue is white. If the solution in the bottle is brown, add appropriate amount
of nitric acid and perchloric acid after cooling, until the solution is completely digested.
Cool it. Add 10 mL of hydrochloric acid solution (5.2.10). Boil it. Cool it slightly.
Transfer to a 50 mL volumetric flask. Use water to wash the Kjeldahl flask 3 ~ 5 times.
Combine the washing solution into the volumetric flask. Then use water to make the
volume reach to the mark. Shake well. Prepare for determination.
When the specimen digestion solution contains less than 10 μg of arsenic, it can be
directly transferred to the arsine generator. Add 7 mL of hydrochloric acid. Add water
to make the volume of the solution in the bottle 40 mL. After adding 2 mL of potassium
iodide, proceed according to the steps of 5.4.3.
At the same time, under the same conditions, carry out the reagent blank test.
5.4.1.2 Hydrochloric acid dissolution method
5.4.1.2.1 It should not add sulfuric acid to mineral element feed additives; the sample
shall be dissolved by hydrochloric acid. Weigh 1 g ~ 3 g of specimen (accurate to 0.0001
g), into a 100 mL tall beaker. Add a little water to moisten the specimen. Slowly add 10
mL of hydrochloric acid solution (5.2.11). After the intense reaction, slowly add 8 mL
of hydrochloric acid. Use water to dilute it to about 30 mL. Boil it. Transfer to a 50 mL
volumetric flask. Wash the beaker 3 ~ 4 times. Combine the washing solution into the
volumetric flask. Use water to make its volume reach to the mark. Shake well. Prepare
for use.
When the specimen digestion solution contains less than 10 μg of arsenic, it can be
directly transferred to the generator, diluted to 40 mL by water and boiled. Proceed the
following steps according to the steps of 5.4.3, from "Add 2 mL of potassium iodide".
In addition, a few mineral feeds are rich in sulfur, which seriously interferes with the
determination of arsenic. After dissolving the sample with hydrochloric acid, add 5 mL
of lead acetate solution (5.2.12) into the tall beaker. Boil it. Let it stand for 20 minutes.
The formed lead sulfide precipitate is removed by filtration. Make the volume reach to
50 mL. Proceed the following, according to the steps specified in 5.4.3.
At the same time, under the same conditions, do a reagent blank test.
5.4.1.2.2 Dissolving samples of copper sulfate and basic copper chloride: Weigh 0.1 g
~ 0.5 g (accurate to 0.0001 g) of the specimen, into the arsine generator (in case of
samples with high arsenic content, first make the volume reach to the mark; divide-take
specimen, so that the arsenic content in the test solution is within the working curve).
Add 5 mL of water to dissolve. Add 2 mL of acetic acid (5.2.5) and 1.5 g of potassium
iodide (5.2.6). Let it stand for 5 min. Add 0.2 g of L-ascorbic acid (5.2.7) to dissolve it.
Add 10 mL of hydrochloric acid. Then use water to dilute to 40 mL. Shake well,
Proceed the following, according to the steps specified in 9.3.
At the same time, under the same conditions, do a reagent blank test.
5.4.1.3 Dry ashing method
Additive premixed feed, concentrated feed, compound feed, single feed, feed additives
may choose dry ashing method.
Weigh 2 g ~ 3 g of the specimen (accurate to 0.0001 g) into a 30 mL porcelain crucible.
Add 5 mL of magnesium nitrate solution (5.2.13). Mix well. Evaporate to dryness at a
low temperature or in boiling water bath. Carbonize at low temperature until smokeless.
After that, transfer to a high-temperature furnace for ashing at a constant temperature
of 550 °C, for 3.5 h ~ 4 h. Take it out to cool. Slowly add 10 mL of hydrochloric acid
solution (5.2.11). After the intense reaction, boil and transfer to a 50 mL volumetric
flask. Use water to wash the crucible, for 3 ~ 5 times. Combine the washing solution
into the volumetric flask. Make the volume reach to the mark. Shake well. Prepare for
test.
When the said specimen contains less than 10 μg of arsenic, it can be directly transferred
to the generator. Add another 8 mL of hydrochloric acid. Add water to about 40 mL.
Add 1 g of ascorbic acid (5.2.7) to dissolve. Operate according to the steps specified in
5.4.3.
At the same time, under the same conditions, do a reagent blank test.
5.4.2 Standard curve drawing
Accurately pipette 0.00 mL, 1.00 mL, 2.00 mL, 4.00 mL, 6.00 mL, 8.00 mL, 10.00 mL
of arsenic standard working solution (1.0 μg/mL) to the generating bottle. Add 10 mL
of hydrochloric acid. Add water to dilute to 40 mL. Follow the steps specified in 5.4.3,
starting from "Add 2 mL of potassium iodide". Measure the absorbance. Obtain the
parameters of the regression equation or draw standard curve. When changing the batch
number of zinc particles or newly preparing Ag-DDTC absorption solution, potassium
iodide solution, stannous chloride solution, the standard curve shall be drawn again.
5.4.3 Reduction reaction and colorimetric determination
6.2.1 Mixed acid solution (B): HNO3 + H2SO4 + HClO4 = 20 + 2 + 3.
6.2.2 Aqueous solution of methyl orange: 1 g/L; pH3.0 (red) ~ 4.0 (orange).
6.2.3 Ammonia solution: 1 + 1.
6.2.4 Tartaric acid solution: 200 g/L.
Weigh 100 g of tartaric acid. Add appropriate amount of water. Slightly heat to dissolve.
Make its volume reach to 500 mL, after cooling.
6.2.5 Potassium hydride tablets: KBH4:NaCl = 1:5
Mix potassium borohydride and sodium chloride, at a mass ratio of 1:5. Dry at 90 °C ~
100 °C for 2 h. Press it, at a pressure of 2 kPa, to form tablet, which has a diameter of
10 mm, a thickness of 5 mm, a mass of 1.0 g ± 0.1 g. It shall be protected from moisture
during pressing and storage.
6.3 Equipment
Same as 5.3.
6.4 Analytical procedures
6.4.1 Handling of samples
6.4.1 Mixed acid digestion method
For compound feed and single feed, it should adopt three-acid digestion method. Weigh
2.0 g ~ 3.0 g of the specimen (accurate to 0.0001 g). Put it in a 250 mL Kjeldahl bottle.
Add a little water to wet the specimen. Add 25 mL of mixed acid solution (B) (6.2.1).
Put it on the electric furnace. Start digestion from room temperature. After the sample
solution is boiled, turn off the electric furnace for 10 ~ 15 minutes. Continue heating
and digestion, until white smoke (SO3) is emitted for several minutes. At this time, the
solution shall be clear, colorless or light yellow; the volume is similar to the
consumption of sulfuric acid; the residue is white. Slightly cool it. Transfer to a 100 mL
arsine generator. Wash the Kjeldahl bottle 3 ~ 4 times. Use water to combine the
washing solution into the generator, to make the volume of the solution in the bottle
about 30 mL. Proceed the following steps according to 6.4.2 and 6.4.3.
At the same time, under the same conditions, do a reagent blank test.
Note: Drive off all the nitric acid during digestion; otherwise, the result will be relatively low.
6.4.1.2 Hydrochloric acid dissolution method
It should not add sulfuric acid to mineral element feed additives, but the specimen shall
be dissolved with hydrochloric acid. Weigh 0.5 g ~ 2.0 g of the specimen (accurate to
0.0001 g) into the generator. Slowly add 5 mL of hydrochloric acid solution (5.2.11)
dropwise. After the intense reaction, slowly add 3 mL ~ 4 mL of hydrochloric acid. Use
water to dilute it to about 30 mL. Boil it. After the specimen is dissolved, proceed
according to the operation steps 6.4.2 and 6.4.3.
At the same time, under the same conditions, do a reagent blank test.
6.4.1.3 Dry ashing method
For additive premixed feed, concentrated feed, compound feed, single feed, feed
additives, it may choose dry ashing method.
Weigh 1.0 g ~ 2.0 g of the specimen (accurate to 0.0001 g), into a 30 mL porcelain
crucible. Transfer it to a high-temperature furnace, after low-temperature carbonization.
Ash it at a constant temperature of 550 °C, for 3 h. Take it out to cool. Slowly add 10
mL of hydrochloric acid solution (5.2.11). Boil it after the intense reaction. Transfer it
to an arsine generator. Add water to about 30 mL. Add 1 g of ascorbic acid (5.2.7) to
dissolve. Proceed according to the operation steps 6.4.2 and 6.4.3.
At the same time, under the same conditions, do a reagent blank test.
6.4.2 Ammonia water (1 + 1) to adjust the pH value of solution
Add 2 drops of methyl orange indicator (6.2.2) to the generator. Use ammonia water (1
+ 1) (6.2.3), to adjust the pH value to orange. Then add hydrochloric acid solution
(5.2.10) dropwise, until it just turns red. Add 6.0 mL of tartaric acid solution (6.2.4).
Use water to dilute it to 50 mL.
6.4.3 Reduction reaction and colorimetric determination
Accurately pipette 5.00 mL of absorption liquid into the absorption bottle. Connect the
generation absorption device (no air leak; the catheter is plugged with loose lead acetate
cotton). Quickly add a piece of potassium borohydride, from the side pipe of the
generator. Immediately cover the stopper tightly. When the reaction is finished, add a
second slice. Gently shake the generator 2 ~ 3 times, during the reaction. After the
reaction is over, use the original absorption solution (5.2.16) as a reference, to measure
at 520 nm with a 1 cm colorimetric cell.
Note: During the reduction reaction, the leakage of toxic arsine gas shall be prevented.
6.4.4 Standard curve drawing
Accurately pipette 0.00 mL, 1.00 mL, 2.00 mL, 4.00 mL, 6.00 mL, 8.00 mL of arsenic
standard working solution (1.0 μg/mL), into the generator bottle. Add water to 40 mL.
Add 6 mL of tartaric acid solution (6.2.4). Proceed the following, according to the steps
specified in 6.4.3, to measure the absorbance. Find out the parameters of the regression
equation or draw the standard curve.
make its volume reach to the mark. Shake well. Prepare for use. At the same time, make
a reagent blank.
At the same time, under the same conditions, do a reagent blank test.
7.4.1.2 Dry ashing method
For additive premixed feed, concentrated feed, compound feed, single feed, feed
additives, it may choose dry ashing method.
Weigh 2 g ~ 5 g of the specimen (accurate to 0.0001 g) into a 30 mL porcelain crucible.
Add 5 mL of magnesium nitrate solution (5.2.13). Mix well. Evaporate to dryness at
low temperature or in a boiling water bath. Carbonize at low temperature to smokeless.
Then transfer it into a high-temperature furnace, for ashing at a constant temperature of
550 °C for 3.5 h ~ 4 h. Take it out to cool. Slowly add 10 mL of hydrochloric acid
solution (5.2.11). After the intense reaction, boil and transfer to a 50 mL volumetric
flask. Add 2.5 mL of thiourea solution (7.2.3), into the volumetric flask. Use water to
wash the crucible 3 ~ 5 times. Combine the washing solution into a volumetric flask.
Use water to make its volume reach to the mark. Shake well. Prepare for determination.
At the same time, make a reagent blank.
At the same time, under the same conditions, do a reagent blank test.
7.4.2 Standard series preparation
Accurately pipette 0.00 mL, 0.10 mL, 0.4 mL, 1.00 mL, 4.00 mL, 10.00 mL of arsenic
standard working solution (1.0 μg/mL), into 50 mL volumetric flasks (each equivalent
dry arsenic concentration of 0 ng/mL, 2.0 ng/mL, 8.0 ng/mL, 20.0 ng/mL, 80.0 ng/mL,
200.0 ng/mL). Add 1.5 mL of hydrochloric acid (5.2.4) and 2.5 mL of thiourea solution
(7.2.3). Add water to the mark. Shake well. Prepare for determination.
7.4.3 Determination
7.4.3.1 Instrument reference conditions
Photomultiplier tube voltage: 200 V ~ 400 V;
Arsenic hollow cathode lamp current: 15 mA ~ 100 mA;
Atomizer temperature: 200 °C;
Atomizer height: 8 mm;
Carrier gas flow: 300 mL/min ~ 600 mL/mtn;
Shielding gas flow: 800 mL/min;
Reading time: 7.0 s ~ 15.0 s;
......
|