This standard specifies the instruments, analytical procedures and result calculation for the determination of peroxide value of animal and vegetable fats and oils. This standard is applicable to the determination of peroxide value of animal and vegetable fats and oils. GB/T 5538-1995 Determination of peroxide value of fats and oils GB/T5538-1995 Standard download decompression password: www.bzxz.net

GB/T5538-1995
National Standard of the People's Republic of China
Determination of peroxide value of oils and fats
Oils and fats-Determination of peroxide value GB/T5538-1995
Replaces GB5538-85
This standard is equivalent to the international standard ISO3960:1977 "Animal and vegetable oils and fats-Determination of peroxide value".
1 Subject content and scope of application
This standard specifies the instruments, analysis steps and result calculation used for the determination of peroxide value of animal and vegetable oils and fats. This standard is applicable to the determination of peroxide value of animal and vegetable oils and fats. 2 Reference standards
GB/T15687 Preparation of oil sample
3 Definition
Peroxide value: The amount of potassium iodide oxidized by the sample under the following operating conditions, expressed in milligrams of active oxygen per kilogram.
4 Principle
In the sample of acetic acid and chloroform solution, potassium iodide is used to react with the sample. After the reaction is completed, the precipitated iodine is titrated with sodium thiosulfate standard solution.
5 Instruments and equipment
5.1 Analytical balance: sensitivity 0.1mg.
5.2 Conical flask with stopper: 250mL.
5.3 Pipette: 5, 10, 15mL.
5.4 Measuring cylinder: 100mL
55 Burette: 10mL, minimum graduation value 0.05mL. 6 Reagents and solutions
The reagents listed in this standard are all analytically pure, and the water is distilled water. 6.1 Chloroform GB682
6.2 Acetic acid GB676
6.3 Potassium iodide GB1271
6.4 Saturated potassium iodide solution, in which free iodine and iodate cannot be present|Verification method: Add two drops of 5% starch solution (6.5) and 0.5mL saturated potassium iodide solution (6.4) to 30mL acetic acid-chloroform solution. If a blue color appears, it takes more than one drop of 0.01mol/L sodium thiosulfate standard solution to remove it, and the solution needs to be re-prepared].
Approved by the State Administration of Technical Supervision on August 17, 1995 and implemented on January 1, 1996
GB/T5538-1995
6.5 0.5% starch solution: Dissolve 0.5g soluble starch in 100mL boiling water and boil for 3min. 6.6 Sodium thiosulfate standard solution: prepare 0.01 mol/L and 0.002 mol/L standard solutions. 7 Preparation of samples and sampling quantitybZxz.net
7.1 Prepare samples according to GB/T15687. 7.2 Sample quantity is sampled according to the following table (see Table 1). Table 1
Estimated peroxide value, meq/kg
8 Analysis steps
The test should be carried out under diffuse sunlight or artificial light. 8.1 Weighing of samples: Weigh the sample according to Table 1, accurate to 0.001g. Sample mass, g
8.2 Determination: Add 10mL of chloroform (6.1) to the conical flask (5.2) containing the weighed sample to dissolve the sample, add 15mL of acetic acid (6.2) and 1mL of saturated potassium iodide solution (6.4), quickly cover the bottle stopper, mix the solution for 1min, and let it stand at 15~25℃ in the dark for 5min. Add about 75mL of distilled water, use 0.5% starch solution (6.5) as indicator, and titrate the precipitated iodine with sodium thiosulfate standard solution (6.6) (use 0.002mol/L standard solution when the estimated value is less than 12, and use 0.01mol/L standard solution when it is greater than 12). Shake vigorously during the titration process. Perform parallel determination with the same sample.
8.3 Blank test: Perform a blank test while determining. If the blank test exceeds 0.1mL0.01mol/L sodium thiosulfate standard solution (6.6), the impure reagent should be replaced. 9 Calculation of results
9.1 The peroxide value is calculated as follows:
PV (me / kg)--V×1000
The volume of sodium thiosulfate standard solution (6.6) used for determination, mL; Where: Vi
VoThe volume of sodium thiosulfate standard solution (6.6) used for blank, mL; c—the standardized concentration of sodium thiosulfate mol/L;
The mass of the sample, g.
9.2 When the results of parallel determinations meet the requirements of the allowable difference (9.3), the arithmetic mean is taken as the result. When the result is less than 12, keep one decimal place; when it is greater than 12, keep it to the integer place. 9.3 Allowable difference
The allowable difference is as specified in Table 2.
Approved by the State Administration of Technical Supervision on August 17, 1995 and implemented on January 1, 1996
GB/T5538-1995
Peroxide value (meq/kg)
10Conversion factor
Allowance difference
Express the peroxide value in millimoles of active oxygen per kilogram of fat or oil, or in micrograms of active oxygen per gram of fat or oil. Multiply the result obtained in 9.1 by the conversion factor listed in Table 3: Table 3
Expression method
meq/kg
mmol/kg
Additional remarks:
This standard was proposed by the Ministry of Domestic Trade of the People's Republic of China. This standard is under the jurisdiction of the State Grain Reserves Administration. This standard was drafted by the Institute of Cereal Oil Chemistry of the Ministry of Domestic Trade. The main drafter of this standard is Hao Xicheng.
Conversion factor approved by the State Administration of Technical Supervision on August 17, 1995
Implementation on January 1, 1996
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