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GB/T 13081-2006 English PDF (GB/T13081-2006)
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GB/T 13081-2006: Determination of mercury in feeds
Delivery: 9 seconds. Download (and Email) true-PDF + Invoice.
Newer version: (Replacing this standard) GB/T 13081-2022
Get Quotation: Click GB/T 13081-2006 (Self-service in 1-minute)
Historical versions (Master-website): GB/T 13081-2022
Preview True-PDF (Reload/Scroll-down if blank)
GB/T 13081-2006
ICS 65.120
B 46
GB
NATIONAL STANDARD
OF THE PEOPLE’S REPUBLIC OF CHINA
Replacing GB/T 13081-1991
Determination of mercury in feeds
ISSUED ON. DECEMBER 12, 2006
IMPLEMENTED ON. MARCH 01, 2007
Issued by. General Administration of Quality Supervision, Inspection and
Quarantine of the People's Republic of China;
Standardization Administration of the People's Republic of
China.
3. No action is required - Full-copy of this standard will be automatically and
immediately delivered to your EMAIL address in 0~60 minutes.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Sampling and sample preparation ... 4
4 Method 1. Atomic fluorescence spectrometry (arbitration method) ... 4
5 Method 2. Cold atomic absorption spectrometry ... 9
Foreword
This standard is a revised version of GB/T 13081-1991 “Determination of
mercury in feeds”.
The main differences between this standard and GB/T 13081-1991 are as
follows.
- ADD the atomic fluorescence spectrometry and USE it as an arbitration
method;
- REVISE the preparation of the stannous chloride solution in the cold
atomic absorption spectrometry. PREPARE it in accordance with JJG
548-2004.
The standard shall, from the date of implementation, replace GB/T
13081-1991.
This standard was proposed by AND shall be under the jurisdiction of the
National Feed Industry Standardization Technical Committee.
The drafting organizations of this standard. State Feed Quality Supervision and
Inspection Center (Wuhan), Jiangsu Yixing Tianshi Feed Co., Ltd.
The main drafters of this standard. He Yifan, Zou Sanyuan, Liu Xiaomin, Yang
Lin, Yang Xiankui.
This standard was first published in 1991 as the national standard GB
13081-1991. It is ranked as a non-mandatory standard in 1997, AND its
number is changed into GB/T 13081-1991. This revision is the first revision of
the standard.
Determination of mercury in feeds
1 Scope
This standard specifies the method of determination of mercury in mixed feed,
concentrated feed, premixed feed, and feed additives.
This standard is applicable to the determination of mercury in compound feed,
concentrated feed, premix feed and feed additive.
Atomic fluorescence spectrometry. the detection limit is 0.15 μg/kg, the best
linear range of standard curve is 0 μg/L ~ 60 μg/L; the cold atomic absorption
detection limit. pressure digestion method is 0.4 μg/kg, other digestion method
is 10 μg/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 602-2002 Chemical reagent – Preparations of standard solutions for
impurity
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
JJG 548-2004 Verification regulation of mercury analyzers
3 Sampling and sample preparation
Sampling shall be carried out in accordance with the provisions of GB/T
14699.1. The preparation of the samples shall be carried out in accordance
with the provisions of GB/T 20195.
4 Method 1. Atomic fluorescence spectrometry
(arbitration method)
4.1 Principles
4.5.3 Repeatability
The same analyst performs two determinations against the same sample
simultaneously or continuously, AND the difference between the results
obtained shall be.
- Not more than 100% of the average when the mercury content is less than
or equal to 0.020 mg/kg;
- Not more than 50% of the average when the mercury content is more than
0.020 mg/kg and less than 0.100 mg/kg;
- Not more than 20% of the average when the mercury content is more than
0.100 mg/kg.
5 Method 2. Cold atomic absorption spectrometry
5.1 Principles
In the atomic absorption spectrum, the mercury atoms have a strong
absorption effect on the resonant lines having a wavelength of 253.7 nm.
Samples are subjected to nitric acid - sulfuric acid digestion to convert the
mercury into ionic state. In the strong acid, stannous chloride reduces the
mercury ion into elemental mercury, which is blown out by the carrier of dry
and clean air, subjected to cold atom absorption, AND it is quantified by
comparison with the standard series.
5.2 Reagents and solutions
Unless otherwise specified, the reagents used in this standard are analytical
pure, AND water is deionized water or water of equivalent purity, which shall
comply with the level II requirements of GB/T 6682.
5.2.1 Nitric acid (excellent grade pure).
5.2.2 Hydrochloric acid (excellent grade pure).
5.2.3 Sulfuric acid (excellent grade pure).
5.2.4 10% stannous chloride solution. PREPARE it in accordance with JJG
548-2004; WEIGH 10 g of stannous chloride (excellent grade pure); ADD 20
mL of concentrated hydrochloric acid (5.2.2); slightly HEAT it to make it
dissolve and transparent; ADD water to dilute it to 100 mL; PREPARE it before
use.
5.2.5 Mixed acid solution. MEASURE 10 mL of sulfuric acid (5.2.3); ADD 10
mL of nitric acid (5.2.1); slowly POUR it into 50 mL water; COOL it down; ADD
water to dilute it to 100 mL.
5.2.6 Mercury standard stock solution. same as 4.2.8.
5.4.2 Drawing of standard curve
PIPETTE 0 mL, 0.10 mL, 0.20 mL, 0.30 mL, 0.40 mL, and 0.50 mL of mercury
standard solution (equivalent to 0 μg, 0.01 μg, 0.02 μg, 0.03 μg, 0.04 μg, 0.05
μg of mercury); PLACE them into the reduction bottle (5.3.7); respectively ADD
10 mL of mixed acid solution (5.2.4); ADD 2 mL of stannous chloride solution
(5.2.4); immediately COVER the reduction bottle tightly (5.3.7) for 2 min;
RECORD the maximum absorbance of the mercury analyzer reading indicator.
USE the absorbance as the ordinate and the mercury concentration as the
abscissa, to draw the standard curve.
5.4.3 Determination
ADD 10 mL of the sample digestion solution in the reduction bottle (5.3.7);
ADD 2 mL of stannous chloride solution (5.2.4); immediately COVER the
reduction bottle tightly (5.3.7) for 2 min; RECORD the maximum absorbance of
the mercury analyzer reading indicator.
5.5 Determination results
5.5.1 Calculation
The mercury content in the sample is calculated in accordance with the
formula (2).
Where.
w - The content of mercury in the sample, in milligrams per kilogram
(mg/kg);
m1 - The mass of mercury in the sample digestion solution for the
determination purposes, in micrograms (μg);
m0 - The mass of mercury in the reagent blank solution, in micrograms (μg);
m – The sample mass, in grams (g);
V1 - The total volume of the sample digestion solution, in milliliters (mL);
V2 - The volume of the digestion solution for the determination purposes, in
milliliters (mL).
5.5.2 Expression of analysis results
Each sample is subjected to 2 times of parallel determination, AND the
arithmetic mean is used as the result.
GB/T 13081-2006
ICS 65.120
B 46
GB
NATIONAL STANDARD
OF THE PEOPLE’S REPUBLIC OF CHINA
Replacing GB/T 13081-1991
Determination of mercury in feeds
ISSUED ON. DECEMBER 12, 2006
IMPLEMENTED ON. MARCH 01, 2007
Issued by. General Administration of Quality Supervision, Inspection and
Quarantine of the People's Republic of China;
Standardization Administration of the People's Republic of
China.
3. No action is required - Full-copy of this standard will be automatically and
immediately delivered to your EMAIL address in 0~60 minutes.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Sampling and sample preparation ... 4
4 Method 1. Atomic fluorescence spectrometry (arbitration method) ... 4
5 Method 2. Cold atomic absorption spectrometry ... 9
Foreword
This standard is a revised version of GB/T 13081-1991 “Determination of
mercury in feeds”.
The main differences between this standard and GB/T 13081-1991 are as
follows.
- ADD the atomic fluorescence spectrometry and USE it as an arbitration
method;
- REVISE the preparation of the stannous chloride solution in the cold
atomic absorption spectrometry. PREPARE it in accordance with JJG
548-2004.
The standard shall, from the date of implementation, replace GB/T
13081-1991.
This standard was proposed by AND shall be under the jurisdiction of the
National Feed Industry Standardization Technical Committee.
The drafting organizations of this standard. State Feed Quality Supervision and
Inspection Center (Wuhan), Jiangsu Yixing Tianshi Feed Co., Ltd.
The main drafters of this standard. He Yifan, Zou Sanyuan, Liu Xiaomin, Yang
Lin, Yang Xiankui.
This standard was first published in 1991 as the national standard GB
13081-1991. It is ranked as a non-mandatory standard in 1997, AND its
number is changed into GB/T 13081-1991. This revision is the first revision of
the standard.
Determination of mercury in feeds
1 Scope
This standard specifies the method of determination of mercury in mixed feed,
concentrated feed, premixed feed, and feed additives.
This standard is applicable to the determination of mercury in compound feed,
concentrated feed, premix feed and feed additive.
Atomic fluorescence spectrometry. the detection limit is 0.15 μg/kg, the best
linear range of standard curve is 0 μg/L ~ 60 μg/L; the cold atomic absorption
detection limit. pressure digestion method is 0.4 μg/kg, other digestion method
is 10 μg/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 602-2002 Chemical reagent – Preparations of standard solutions for
impurity
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
JJG 548-2004 Verification regulation of mercury analyzers
3 Sampling and sample preparation
Sampling shall be carried out in accordance with the provisions of GB/T
14699.1. The preparation of the samples shall be carried out in accordance
with the provisions of GB/T 20195.
4 Method 1. Atomic fluorescence spectrometry
(arbitration method)
4.1 Principles
4.5.3 Repeatability
The same analyst performs two determinations against the same sample
simultaneously or continuously, AND the difference between the results
obtained shall be.
- Not more than 100% of the average when the mercury content is less than
or equal to 0.020 mg/kg;
- Not more than 50% of the average when the mercury content is more than
0.020 mg/kg and less than 0.100 mg/kg;
- Not more than 20% of the average when the mercury content is more than
0.100 mg/kg.
5 Method 2. Cold atomic absorption spectrometry
5.1 Principles
In the atomic absorption spectrum, the mercury atoms have a strong
absorption effect on the resonant lines having a wavelength of 253.7 nm.
Samples are subjected to nitric acid - sulfuric acid digestion to convert the
mercury into ionic state. In the strong acid, stannous chloride reduces the
mercury ion into elemental mercury, which is blown out by the carrier of dry
and clean air, subjected to cold atom absorption, AND it is quantified by
comparison with the standard series.
5.2 Reagents and solutions
Unless otherwise specified, the reagents used in this standard are analytical
pure, AND water is deionized water or water of equivalent purity, which shall
comply with the level II requirements of GB/T 6682.
5.2.1 Nitric acid (excellent grade pure).
5.2.2 Hydrochloric acid (excellent grade pure).
5.2.3 Sulfuric acid (excellent grade pure).
5.2.4 10% stannous chloride solution. PREPARE it in accordance with JJG
548-2004; WEIGH 10 g of stannous chloride (excellent grade pure); ADD 20
mL of concentrated hydrochloric acid (5.2.2); slightly HEAT it to make it
dissolve and transparent; ADD water to dilute it to 100 mL; PREPARE it before
use.
5.2.5 Mixed acid solution. MEASURE 10 mL of sulfuric acid (5.2.3); ADD 10
mL of nitric acid (5.2.1); slowly POUR it into 50 mL water; COOL it down; ADD
water to dilute it to 100 mL.
5.2.6 Mercury standard stock solution. same as 4.2.8.
5.4.2 Drawing of standard curve
PIPETTE 0 mL, 0.10 mL, 0.20 mL, 0.30 mL, 0.40 mL, and 0.50 mL of mercury
standard solution (equivalent to 0 μg, 0.01 μg, 0.02 μg, 0.03 μg, 0.04 μg, 0.05
μg of mercury); PLACE them into the reduction bottle (5.3.7); respectively ADD
10 mL of mixed acid solution (5.2.4); ADD 2 mL of stannous chloride solution
(5.2.4); immediately COVER the reduction bottle tightly (5.3.7) for 2 min;
RECORD the maximum absorbance of the mercury analyzer reading indicator.
USE the absorbance as the ordinate and the mercury concentration as the
abscissa, to draw the standard curve.
5.4.3 Determination
ADD 10 mL of the sample digestion solution in the reduction bottle (5.3.7);
ADD 2 mL of stannous chloride solution (5.2.4); immediately COVER the
reduction bottle tightly (5.3.7) for 2 min; RECORD the maximum absorbance of
the mercury analyzer reading indicator.
5.5 Determination results
5.5.1 Calculation
The mercury content in the sample is calculated in accordance with the
formula (2).
Where.
w - The content of mercury in the sample, in milligrams per kilogram
(mg/kg);
m1 - T...
Delivery: 9 seconds. Download (and Email) true-PDF + Invoice.
Newer version: (Replacing this standard) GB/T 13081-2022
Get Quotation: Click GB/T 13081-2006 (Self-service in 1-minute)
Historical versions (Master-website): GB/T 13081-2022
Preview True-PDF (Reload/Scroll-down if blank)
GB/T 13081-2006
ICS 65.120
B 46
GB
NATIONAL STANDARD
OF THE PEOPLE’S REPUBLIC OF CHINA
Replacing GB/T 13081-1991
Determination of mercury in feeds
ISSUED ON. DECEMBER 12, 2006
IMPLEMENTED ON. MARCH 01, 2007
Issued by. General Administration of Quality Supervision, Inspection and
Quarantine of the People's Republic of China;
Standardization Administration of the People's Republic of
China.
3. No action is required - Full-copy of this standard will be automatically and
immediately delivered to your EMAIL address in 0~60 minutes.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Sampling and sample preparation ... 4
4 Method 1. Atomic fluorescence spectrometry (arbitration method) ... 4
5 Method 2. Cold atomic absorption spectrometry ... 9
Foreword
This standard is a revised version of GB/T 13081-1991 “Determination of
mercury in feeds”.
The main differences between this standard and GB/T 13081-1991 are as
follows.
- ADD the atomic fluorescence spectrometry and USE it as an arbitration
method;
- REVISE the preparation of the stannous chloride solution in the cold
atomic absorption spectrometry. PREPARE it in accordance with JJG
548-2004.
The standard shall, from the date of implementation, replace GB/T
13081-1991.
This standard was proposed by AND shall be under the jurisdiction of the
National Feed Industry Standardization Technical Committee.
The drafting organizations of this standard. State Feed Quality Supervision and
Inspection Center (Wuhan), Jiangsu Yixing Tianshi Feed Co., Ltd.
The main drafters of this standard. He Yifan, Zou Sanyuan, Liu Xiaomin, Yang
Lin, Yang Xiankui.
This standard was first published in 1991 as the national standard GB
13081-1991. It is ranked as a non-mandatory standard in 1997, AND its
number is changed into GB/T 13081-1991. This revision is the first revision of
the standard.
Determination of mercury in feeds
1 Scope
This standard specifies the method of determination of mercury in mixed feed,
concentrated feed, premixed feed, and feed additives.
This standard is applicable to the determination of mercury in compound feed,
concentrated feed, premix feed and feed additive.
Atomic fluorescence spectrometry. the detection limit is 0.15 μg/kg, the best
linear range of standard curve is 0 μg/L ~ 60 μg/L; the cold atomic absorption
detection limit. pressure digestion method is 0.4 μg/kg, other digestion method
is 10 μg/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 602-2002 Chemical reagent – Preparations of standard solutions for
impurity
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
JJG 548-2004 Verification regulation of mercury analyzers
3 Sampling and sample preparation
Sampling shall be carried out in accordance with the provisions of GB/T
14699.1. The preparation of the samples shall be carried out in accordance
with the provisions of GB/T 20195.
4 Method 1. Atomic fluorescence spectrometry
(arbitration method)
4.1 Principles
4.5.3 Repeatability
The same analyst performs two determinations against the same sample
simultaneously or continuously, AND the difference between the results
obtained shall be.
- Not more than 100% of the average when the mercury content is less than
or equal to 0.020 mg/kg;
- Not more than 50% of the average when the mercury content is more than
0.020 mg/kg and less than 0.100 mg/kg;
- Not more than 20% of the average when the mercury content is more than
0.100 mg/kg.
5 Method 2. Cold atomic absorption spectrometry
5.1 Principles
In the atomic absorption spectrum, the mercury atoms have a strong
absorption effect on the resonant lines having a wavelength of 253.7 nm.
Samples are subjected to nitric acid - sulfuric acid digestion to convert the
mercury into ionic state. In the strong acid, stannous chloride reduces the
mercury ion into elemental mercury, which is blown out by the carrier of dry
and clean air, subjected to cold atom absorption, AND it is quantified by
comparison with the standard series.
5.2 Reagents and solutions
Unless otherwise specified, the reagents used in this standard are analytical
pure, AND water is deionized water or water of equivalent purity, which shall
comply with the level II requirements of GB/T 6682.
5.2.1 Nitric acid (excellent grade pure).
5.2.2 Hydrochloric acid (excellent grade pure).
5.2.3 Sulfuric acid (excellent grade pure).
5.2.4 10% stannous chloride solution. PREPARE it in accordance with JJG
548-2004; WEIGH 10 g of stannous chloride (excellent grade pure); ADD 20
mL of concentrated hydrochloric acid (5.2.2); slightly HEAT it to make it
dissolve and transparent; ADD water to dilute it to 100 mL; PREPARE it before
use.
5.2.5 Mixed acid solution. MEASURE 10 mL of sulfuric acid (5.2.3); ADD 10
mL of nitric acid (5.2.1); slowly POUR it into 50 mL water; COOL it down; ADD
water to dilute it to 100 mL.
5.2.6 Mercury standard stock solution. same as 4.2.8.
5.4.2 Drawing of standard curve
PIPETTE 0 mL, 0.10 mL, 0.20 mL, 0.30 mL, 0.40 mL, and 0.50 mL of mercury
standard solution (equivalent to 0 μg, 0.01 μg, 0.02 μg, 0.03 μg, 0.04 μg, 0.05
μg of mercury); PLACE them into the reduction bottle (5.3.7); respectively ADD
10 mL of mixed acid solution (5.2.4); ADD 2 mL of stannous chloride solution
(5.2.4); immediately COVER the reduction bottle tightly (5.3.7) for 2 min;
RECORD the maximum absorbance of the mercury analyzer reading indicator.
USE the absorbance as the ordinate and the mercury concentration as the
abscissa, to draw the standard curve.
5.4.3 Determination
ADD 10 mL of the sample digestion solution in the reduction bottle (5.3.7);
ADD 2 mL of stannous chloride solution (5.2.4); immediately COVER the
reduction bottle tightly (5.3.7) for 2 min; RECORD the maximum absorbance of
the mercury analyzer reading indicator.
5.5 Determination results
5.5.1 Calculation
The mercury content in the sample is calculated in accordance with the
formula (2).
Where.
w - The content of mercury in the sample, in milligrams per kilogram
(mg/kg);
m1 - The mass of mercury in the sample digestion solution for the
determination purposes, in micrograms (μg);
m0 - The mass of mercury in the reagent blank solution, in micrograms (μg);
m – The sample mass, in grams (g);
V1 - The total volume of the sample digestion solution, in milliliters (mL);
V2 - The volume of the digestion solution for the determination purposes, in
milliliters (mL).
5.5.2 Expression of analysis results
Each sample is subjected to 2 times of parallel determination, AND the
arithmetic mean is used as the result.
GB/T 13081-2006
ICS 65.120
B 46
GB
NATIONAL STANDARD
OF THE PEOPLE’S REPUBLIC OF CHINA
Replacing GB/T 13081-1991
Determination of mercury in feeds
ISSUED ON. DECEMBER 12, 2006
IMPLEMENTED ON. MARCH 01, 2007
Issued by. General Administration of Quality Supervision, Inspection and
Quarantine of the People's Republic of China;
Standardization Administration of the People's Republic of
China.
3. No action is required - Full-copy of this standard will be automatically and
immediately delivered to your EMAIL address in 0~60 minutes.
Table of Contents
Foreword ... 3
1 Scope ... 4
2 Normative references ... 4
3 Sampling and sample preparation ... 4
4 Method 1. Atomic fluorescence spectrometry (arbitration method) ... 4
5 Method 2. Cold atomic absorption spectrometry ... 9
Foreword
This standard is a revised version of GB/T 13081-1991 “Determination of
mercury in feeds”.
The main differences between this standard and GB/T 13081-1991 are as
follows.
- ADD the atomic fluorescence spectrometry and USE it as an arbitration
method;
- REVISE the preparation of the stannous chloride solution in the cold
atomic absorption spectrometry. PREPARE it in accordance with JJG
548-2004.
The standard shall, from the date of implementation, replace GB/T
13081-1991.
This standard was proposed by AND shall be under the jurisdiction of the
National Feed Industry Standardization Technical Committee.
The drafting organizations of this standard. State Feed Quality Supervision and
Inspection Center (Wuhan), Jiangsu Yixing Tianshi Feed Co., Ltd.
The main drafters of this standard. He Yifan, Zou Sanyuan, Liu Xiaomin, Yang
Lin, Yang Xiankui.
This standard was first published in 1991 as the national standard GB
13081-1991. It is ranked as a non-mandatory standard in 1997, AND its
number is changed into GB/T 13081-1991. This revision is the first revision of
the standard.
Determination of mercury in feeds
1 Scope
This standard specifies the method of determination of mercury in mixed feed,
concentrated feed, premixed feed, and feed additives.
This standard is applicable to the determination of mercury in compound feed,
concentrated feed, premix feed and feed additive.
Atomic fluorescence spectrometry. the detection limit is 0.15 μg/kg, the best
linear range of standard curve is 0 μg/L ~ 60 μg/L; the cold atomic absorption
detection limit. pressure digestion method is 0.4 μg/kg, other digestion method
is 10 μg/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 602-2002 Chemical reagent – Preparations of standard solutions for
impurity
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
JJG 548-2004 Verification regulation of mercury analyzers
3 Sampling and sample preparation
Sampling shall be carried out in accordance with the provisions of GB/T
14699.1. The preparation of the samples shall be carried out in accordance
with the provisions of GB/T 20195.
4 Method 1. Atomic fluorescence spectrometry
(arbitration method)
4.1 Principles
4.5.3 Repeatability
The same analyst performs two determinations against the same sample
simultaneously or continuously, AND the difference between the results
obtained shall be.
- Not more than 100% of the average when the mercury content is less than
or equal to 0.020 mg/kg;
- Not more than 50% of the average when the mercury content is more than
0.020 mg/kg and less than 0.100 mg/kg;
- Not more than 20% of the average when the mercury content is more than
0.100 mg/kg.
5 Method 2. Cold atomic absorption spectrometry
5.1 Principles
In the atomic absorption spectrum, the mercury atoms have a strong
absorption effect on the resonant lines having a wavelength of 253.7 nm.
Samples are subjected to nitric acid - sulfuric acid digestion to convert the
mercury into ionic state. In the strong acid, stannous chloride reduces the
mercury ion into elemental mercury, which is blown out by the carrier of dry
and clean air, subjected to cold atom absorption, AND it is quantified by
comparison with the standard series.
5.2 Reagents and solutions
Unless otherwise specified, the reagents used in this standard are analytical
pure, AND water is deionized water or water of equivalent purity, which shall
comply with the level II requirements of GB/T 6682.
5.2.1 Nitric acid (excellent grade pure).
5.2.2 Hydrochloric acid (excellent grade pure).
5.2.3 Sulfuric acid (excellent grade pure).
5.2.4 10% stannous chloride solution. PREPARE it in accordance with JJG
548-2004; WEIGH 10 g of stannous chloride (excellent grade pure); ADD 20
mL of concentrated hydrochloric acid (5.2.2); slightly HEAT it to make it
dissolve and transparent; ADD water to dilute it to 100 mL; PREPARE it before
use.
5.2.5 Mixed acid solution. MEASURE 10 mL of sulfuric acid (5.2.3); ADD 10
mL of nitric acid (5.2.1); slowly POUR it into 50 mL water; COOL it down; ADD
water to dilute it to 100 mL.
5.2.6 Mercury standard stock solution. same as 4.2.8.
5.4.2 Drawing of standard curve
PIPETTE 0 mL, 0.10 mL, 0.20 mL, 0.30 mL, 0.40 mL, and 0.50 mL of mercury
standard solution (equivalent to 0 μg, 0.01 μg, 0.02 μg, 0.03 μg, 0.04 μg, 0.05
μg of mercury); PLACE them into the reduction bottle (5.3.7); respectively ADD
10 mL of mixed acid solution (5.2.4); ADD 2 mL of stannous chloride solution
(5.2.4); immediately COVER the reduction bottle tightly (5.3.7) for 2 min;
RECORD the maximum absorbance of the mercury analyzer reading indicator.
USE the absorbance as the ordinate and the mercury concentration as the
abscissa, to draw the standard curve.
5.4.3 Determination
ADD 10 mL of the sample digestion solution in the reduction bottle (5.3.7);
ADD 2 mL of stannous chloride solution (5.2.4); immediately COVER the
reduction bottle tightly (5.3.7) for 2 min; RECORD the maximum absorbance of
the mercury analyzer reading indicator.
5.5 Determination results
5.5.1 Calculation
The mercury content in the sample is calculated in accordance with the
formula (2).
Where.
w - The content of mercury in the sample, in milligrams per kilogram
(mg/kg);
m1 - T...
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