GB/T 5532-2022Animal and vegetable fats and oils - Determination of iodine value (English PDF)

Foreword

This document was drafted in accordance with the provisions of GB/T 1.1-2020

Directives for standardization - Part 1: Rules for the structure and drafting of

standardizing documents.

This document replaces GB/T 5532-2008 Animal and vegetable fats and oils -

Determination of iodine value. Compared with GB/T 5532-2008, except for the

structural adjustment and editorial changes, the main technical changes are as follows:

-- The requirement of mixing solvents by equal volume (50 mL) is added (see 5.5);

-- The storage method of Wijs reagent is added (see 5.6);

-- The instrument requirements for volumetric flasks, pipettes, and burettes are

added (see 6.4, 6.5, and 6.6);

-- Table 1 is changed (see Table 1; see Table 1 of the 2008 edition);

-- The requirements for preheating and sealing are added in the test procedure (see

9.1);

-- The requirements for rounding off the determination results are changed (see

Table 2; see Table 2 of the 2008 edition);

-- The contents that the requirement to indicate all necessary identification

information of the sample in the test report and the test method refers to the

international standard are added (see Chapter 12; see Chapter 12 of the 2008

edition).

This document is identical to ISO 3961:2018 Animal and vegetable fats and oils -

Determination of iodine value.

The following editorial changes have been made to this document:

-- The relevant formulas are numbered.

1 Scope

This document specifies a method for the determination of the iodine value of animal

and vegetable fats and oils.

Appendix B describes a method for the calculation of the iodine value according to fatty

acid compositional data. This method is not applicable to fish oils. Furthermore, for

cold-pressed, unrefined animal and vegetable oils as well as (partially) hydrogenated

oils, different results can be obtained by the two methods. The calculated iodine value

is affected by impurities and thermal degradation products.

NOTE: The method is based upon the official method Cd 1c-85 of American Oil Chemists Society

(AOCS).

2 Normative references

The following documents contain the provisions which, through normative reference in

this document, constitute the essential provisions of this document. For the dated

referenced documents, only the versions with the indicated dates are applicable to this

document; for the undated referenced documents, only the latest version (including all

the amendments) is applicable to this document.

ISO 661 Animal and vegetable fats and oils - Preparation of test sample

NOTE: GB/T 15687-2008 Animal and vegetable fats and oils - Preparation of test sample (ISO

661:2003, IDT)

3 Terms and definitions

The following terms and definitions are applicable to this document.

The terminological databases of ISO and IEC can be accessed at the following URL:

-- ISO: https://www.iso.org/obp

-- IEC: http://www.electropedia.org/

4 Principle

The sample is dissolved in solvent and then Wijs reagent is added for reaction. After a

specified time, potassium iodide and water are added, and then the solution is titrated

with sodium thiosulfate solution to obtain free iodine.

5 Reagents

WARNING -- Attention is drawn to the regulations that specify the handling of

hazardous substances. The relevant technical, organizational, and personal safety

regulations shall be followed. Wijs reagent may cause severe burns; vapours can

cause lung and eye damage. A fume hood shall be used for the work.