GB/T 13085-2018 PDF English
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| Standard ID | Contents [version] | USD | STEP2 | [PDF] delivery | Name of Chinese Standard | Status |
| GB/T 13085-2018 | English | 105 |
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Determination of nitrite in feeds -- Colorimetry method
| Valid |
| GB/T 13085-2005 | English | 239 |
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3 days
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Determination of nitrite in feed -- Method using colorimetric analysis
| Obsolete |
| GB/T 13085-1991 | English | 199 |
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2 days
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Method for determination of nitrite in feeds
| Obsolete |
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GB/T 13085-2018: Determination of nitrite in feeds -- Colorimetry method---This is an excerpt. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.), auto-downloaded/delivered in 9 seconds, can be purchased online: https://www.ChineseStandard.net/PDF.aspx/GBT13085-2018
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 65.120
B 46
Replacing GB/T 13085-2005
Determination of nitrite in feeds - Colorimetry method
Issued on. SEPTEMBER 17, 2018
Implemented on. APRIL 01, 2019
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 Principle... 4
4 Reagents or materials... 4
5 Instruments and equipment... 5
6 Sample... 6
7 Test steps... 6
8 Test data processing... 7
9 Precision... 7
Foreword
This Standard was drafted in accordance with the rules given in GB/T 1.1-2009.
This Standard replaces GB/T 13085-2005, Determination of nitrite in feed - Method
using colorimetric analysis.
Compared with GB/T 13085-2005, the main technical changes, except editorial changes,
are as follows.
-- Modify the detection limit of the method, and add the quantitation limit of the
method (see Chapter 1; Chapter 1 of the 2005 edition);
-- Modify the preparation method of test solution (see 7.1; 7.1 of the 2005 edition);
-- Modify the preparation method of standard curve (see 7.2; 7.2 of the 2005 edition);
-- Modify the measurement method of absorbance (see 7.3; 7.3 of the 2005 edition);
-- Modify the requirements for precision (see Chapter 9; 8.3 of the 2005 edition).
This Standard shall be under the jurisdiction of National Technical Committee 76 on
Feed Industry of Standardization Administration of China (SAC/TC 76).
Drafting organization of this Standard. Huazhong Agricultural University.
Main drafters of this Standard. Qi Desheng, Zhang Niya, He Qiongyu, Wang Jun, Tao
Can, Zhu Luoyi.
The previous versions – replaced by this Standard – of the standard are.
-- GB/T 13085-1991, GB/T 13085-2005.
Determination of nitrite in feeds - Colorimetry method
1 Scope
This Standard specifies the colorimetry method for the determination of nitrite in feeds.
This Standard applies to the determination of nitrite in feed raw materials, compound
feeds, concentrated feeds and concentrate supplements.
The detection limit of this method is 0.70 mg/kg, and the quantitation limit is 2.0 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 to this document. For
undated references, the latest edition (including any amendment) applies to this
document.
GB/T 6682, Water for analytical laboratory use - Specification and test methods
GB/T 14699.1, Feeding stuffs - Sampling
3 Principle
The sample removes protein under weakly alkaline conditions, and the nitrite in the
sample reacts with p-aminobenzenesulfonic acid under weakly acidic conditions to
form diazo compounds, which are then coupled with N-1-naphthylethylenediamine to
form purple compounds.
4 Reagents or materials
Unless otherwise specified, only use reagents confirmed to be of analytical grade in the
analysis.
4.1 Water. grade-II water as specified in GB/T 6682.
4.2 Dilute hydrochloric acid solution. Take 5 mL of hydrochloric acid; add it to a 100
mL volumetric flask; use water to dilute to a constant volume; mix well.
4.7 Acetic acid solution. Measure 600 mL of glacial acetic acid in a 1 000 mL
volumetric flask; use water to dilute to the mark; mix well.
4.8 P-aminobenzenesulfonic acid solution. Weigh 5.0 g of p-aminobenzenesulfonic
acid; dissolve it in 700 mL of water and 300 mL of glacial acetic acid; mix well; store
in a brown bottle. The validity period is 7 days.
4.9 N-1-Naphthylethylenediamine solution. Weigh 0.1 g of N-1-
naphthylethylenediamine; add acetic acid solution (4.7) to dissolve and dilute to a
constant volume of 100 mL; mix well; put it in a brown bottle; store it in a refrigerator
at 4 °C ~ 10 °C. The validity period is 7 days.
4.10 Color-developing agent. Mix equal volumes of p-aminobenzenesulfonic acid
solution (4.8) and N-1-naphthylethylenediamine solution (4.9) before use.
4.12 Sodium nitrite standard working solution (5.0 μg/mL). Accurately pipette 1.00
mL of sodium nitrite standard stock solution (4.11) into a 100 mL volumetric flask; add
water to dilute to a constant volume to the mark; mix well. Prepare when necessary.
5 Instruments and equipment
5.1 Spectrophotometry.
5.2 Water bath. The temperature control range is 25 °C ~ 100 °C; the temperature
control accuracy is ±1 °C.
6 Sample
Collect samples according to GB/T 14699.1, and prepare samples according to GB/T
20195.
7 Test steps
7.1 Preparation of test solution
Perform two tests in parallel. Weigh about 5 g of sample, accurate to 0.001 g; place it
in a 200 mL conical flask; add 70 mL of water and 1.2 mL of sodium hydroxide solution
(4.6); mix well; use sodium hydroxide solution (4.6) to adjust the pH to 8 ~ 9; add 10
mL of zinc sulfate solution (4.5);
7.2 Preparation of nitrite standard curve
Accurately pipette 0 mL, 0.4 mL, 0.8 mL, 1.2 mL, 1.6 mL and 2.0 mL of sodium nitrite
standard working solution (4.12), respectively, into 25 mL brown volumetric flasks
(equivalent to 0 μg, 2 μg, 4 μg, 6 μg, 8 μg, 10 μg of sodium nitrate); after respectively
adding 4.5 mL of ammonium chloride buffer solution (4.4) and 2.5 mL of acetic acid
solution (4.7), immediately add 5.0 mL of color-developing agent (4.10);
7.3 Determination of test solution
Pipette two parts of 10.0 mL test solution (7.1) into 25 mL volumetric flasks a and b,
respectively. Add 4.5 mL of ammonium chloride buffer solution (4.4) and 2.5 mL of
acetic acid solution (4.7) into the volumetric flask a; then, use water to dilute to the
mark; mix well.
8 Test data processing
The content of nitrite in the sample is calculated according to the mass fraction w of
sodium nitrite (NaNO2); the value is expressed in milligrams per kilogram (mg/kg), and
calculated according to Formula (1).
9 Precision
The absolute difference between two independent test results obtained under
repeatability conditions and their arithmetic mean is not more than 10% of the mean.
......
Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al.
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