Foreword
Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.
This standard is developed 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.
In addition to editorial changes, the following main technical changes have been made with respect to GB/T 13085-2005:
——the detection limit for the purpose of the method is modified and the limit of quantitation is added (see Clause 1; Clause 1 of Edition 2005);
——the preparation method of test solution is modified (see 7.1; 7.1 of Edition 2005);
——the preparation method of standard curve is modified (see 7.2; 7.2 of Edition 2005);
——the determination method for absorbance is modified (see 7.3; 7.3 of Edition 2005);
——the requirements for precision are modified (see Clause 9; 8.3 of Edition 2005)
This standard was proposed by and is under the jurisdiction of the National Technical Committee on Feed Industry of Standardization Administration of China (SAC/TC 76).
The previous editions of this standard are as follows:
——GB/T 13085-1991 and GB/T 13085-2005.
Determination of nitrite in feeds - Colorimetry method
1 Scope
This standard specifies the colorimetry method for determination of nitrite in feeds.
This standard is applicable to the determination of nitrite in feedstuffs, formula feeds, concentrates and concentrate supplements.
For the purpose of this method, the limit of detection is 0.70mg/kg, and the limit of quantitation is 2.0mg/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 14699.1 Feeding stuffs - Sampling
GB/T 20195 Animal feeding stuffs - Preparation of test samples
3 Principle
Protein is removed from the test sample under weak alkaline condition, nitrite in the test sample reacts with p-aminobenzene sulfonic acid under weak acidic condition to generate diazo compound, which coupled with N-1-naphthyl ethylenediamine to generate purplish red compound. Colorimetric determination is carried out at the wavelength of 538nm.
Foreword i
1 Scope
2 Normative references
3 Principle
4 Reagents or materials
5 Instruments and apparatus
6 Sample
7 Test steps
8 Test data processing
9 Precision
