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 13083-2002 Determination of fluorine in feed - Ion selective electrode method. In addition to a number of editorial changes, the following technical changes have been made with respect to GB/T 13083-2002:
——the application scope of the standard is expanded as "This standard is applicable to feeds, feedstuffs, phosphates and mixed feed additives with aluminosilicate as carrier";
——the limit of detection for the purpose of the method is modified;
——the expression of the principle is modified;
——the measuring range of acidity meter and fluorine ion selective electrode is modified;
——the preparation method of test sample for feedstuff stone powders is added;
——the preparation method of test sample for mixed feed additives with aluminosilicate as carrier is added;
——the results expression is changed from 0.1mg/kg to mg/kg.
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 13083-1991 and GB/T 13083-2002.
Determination of fluorine in feeds - Ion selective electrode method
1 Scope
This standard specifies the determination of fluorine in feeds by ion selective electrode method.
This standard is applicable to feeds, feedstuffs, phosphates and mixed feed additives with aluminosilicate as carrier.
For the purpose of this method, the limit of detection is 3mg/kg (take 1g test sample, and dilute to 50mL).
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
The test sample is extracted by hydrochloric acid solution and adjusted to pH=5~6 with total ionic strength adjustment buffer to eliminate the interference of acidity and ions such as Al3+, Fe3+, Ca2+, Mg2+ and SiO32- which can form complexes with fluorine ions, and the potential difference between fluorine ion selective electrode and saturated calomel electrode is measured by ion meter. The potential difference has a linear relationship with the logarithm of fluorine ion activity (concentration) in the solution. The fluorine content in the test sample is calculated from the fluorine ion concentration corresponding to the potential difference of unknown sample solution calculated according to the linear equation obtained from the potential difference measured by fluorine standard series with known concentration.
4 Reagents or materials
Unless otherwise specified, analytically-pure reagents and Grade 3 water (defined in GB/T 6682) are adopted for the purpose of this method.
Foreword i
1 Scope
2 Normative references
3 Principle
4 Reagents or materials
5 Instruments and apparatus
6 Preparation of test sample
7 Test steps
8 Test data processing
9 Precision
