According to AOCS CD 8b (Peroxide Value Acetic Acid-Isooctane Method); ISO (Animal and vegetable fats and oils. SAMPLING AND ANALYSIS OF COMMERCIAL FATS AND OILS AOCS Official Method Cd 8b Revised Peroxide Value Acetic. AOCS has standardized a method for. PV determination with chloroform (Cd. 8- 53) and with isooctane (Cd 8b). The latter method uses a mixture of acetic.
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Many unconventional edible plant oils are available on the market, but their quality and composition are often unknown. If the titration is less than 0. Allow the solution to stand for exactly 1 min, thoroughly shaking the solution at ce three times during the 1 min, and then immediately add 30 mL of distilled water.
The following are suitable starches: Make certain the solution remains saturated during use, as indicated by the presence of undissolved KI crystals. When completely melted, remove the sample from the hot plate or oven and allow to settle in a warm place until the aqueous portion and most of the milk solids have settled to the bottom. Decant the oil into a clean beaker and filter through a Whatman no.
The substances are generally assumed to be peroxides or other similar products of fat oxidation. Add the thiosulfate solution dropwise until the blue color just disappears see Notes, 4. Starch indicator solution—tested for sensitivity, prepared by making a paste with 1 g of starch see Notes, 1 and a small amount of cold distilled water.
KI in mL water and rotate to mix. A fume hood should be used at all times when using chloroform. Do not reheat for filtration unless absolutely necessary. Add, while stirring, to mL of boiling water and boil for a few seconds.
If a blue color is formed that requires more than 1 drop of 0. It is nonflammable, but will burn on prolonged exposure to flame or high temperature. Analysts may use 0. Oil and Soap 9: Do not reheat for filtration unless absolutely necessary. Immediately remove from heat and cool.
AOCS CD 8b – 90 Peroxido
It is toxic by inhalation and has anesthetic properties. Isooctane has been proposed as a replacement for chloroform in this method.
Burette—with 25 mL or 50 mL, class A, graduated in 0. Aoce as directed in Procedure for Fats and Oils, paragraphs 1—4. Weigh the test portion Table 1 into a mL Erlenmeyer flask with glass stopper and add 50 mL of the 3: Add 1—2 mL of starch indicator and continue the titration, aaocs the thiosulfate solution slowly until the blue color just disappears.
Fresh indicator must be prepared when the end point of the titration from blue to colorless fails to be sharp. When completely melted, remove the sample from the hot plate or oven and allow to settle in a warm place until the aqueous portion and most of the milk solids have settled to the bottom.
It is a strong oxidizing agent and a dangerous fire risk aoccs in contact with organic chemicals. Acetic acid in 8n pure state is moderately toxic by ingestion and inhalation. Repeatability—The difference between two test results on the same material, in the same laboratory under the same conditions, should not exceed the repeatability value, r.
The TLV in air is 10 ppm.
AOCS Cd _图文_百度文库
Test for sensitivity—Place 5 mL of starch solution in mL of water and add 0. Add the thiosulfate solution dropwise until the blue color cf disappears see Notes, 3 and 4.
The test should be carried out in diffuse daylight or in artificial light shielded from a direct light source.