Methods. Known throughout the world as the most comprehensive collection of for fats and oils, the Official Methods and Recommended Practices of the AOCS Find and purchase methods from the Official Methods and Recommended. cation of the AOCS Cd 3d method, through a statistical . Methods. AOCS Cd 3d Official Method [8]. The acid number in oils and fats is determined. ufacturing, Kyoto, Japan) according to the AOCS Official. Method Cd 3d [23]. All AV analysis results were expressed as mg KOH/g oil.

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The electrodes were calibrated as usual with aqueous buffer solutions of pH 7. The proposed green potentiometric procedure presents less toxic characteristics than the official procedures as it uses ethanol and water as solvents in place of isopropyl alcohol and toluene and therefore is greener.

The acid number is a parameter that quantifies oacs acid products of degradation reactions of an oil or a fat. A Metrohm model pH meter and a Metrohm Titrando titrator were used to perform, respectively, point-by-point and automatic titration.

Soy, corn, canola, sunflower, linseed and castor oils and swine lard were used in the present study.

How to cite this article. Considering the above observations, the green method developed in this work can be proposed for the routine determination of the acid number of oils and fats.

High concentrations mean loss of money as the rating of the product decreases. Weigh the sample directly into a mL tall form beaker. Because of the above observations, it is evident that the precision of the proposed green potentiometric method is higher than of the all others offixial used for comparison. This situation not only reduces the time of the analysis, but also minimizes the possible effect of dehydration offidial the electrode as it remains for a acos period in contact with the 1: For the castor oil, however, no concordance was found.


The limits of confidence of the parameters a and b are calculated as confidence limits: Therefore, the present work has as objective to apply potentiometric detection to the titrimetric method aiming at low cost, operational simplicity and, especially, as environmentally friendly procedure.

The other methods present similar standard deviation among them with a little lower value for RSD for green visual procedure. For linseed, no statistical concordance was observed.

In order to verify the accuracy of the potentiometric procedure developed with respect to the AOCS Cd 3d and to the two other applied methods, a statistical weighted linear regression procedure was used. Reagents, solutions and solvents All the reagents and solvents ofdicial of analytical grade.

Services on Demand Journal. Canola, sunflower, linseed, castor, corn and soy oils as ogficial as swine lard, a total of twelve real samples, were analyzed. Using a graduated cylinder, add 75 mL of methoc 1: The automatic potentiometric titration is usually done in about 5 min, whereas the point-by-point procedure needs about 30 min.

The potentiometric method herein proposed was performed point-by-point and also using an automatic titrator in order to obtain the acid number of the solvents.

A green potentiometric method for determination of the acid number of oils and fats

AOCS Cd 3d official method This solvent mixture is previously neutralized with the standard KOH solution using phenolphthalein until the appearance of a slight pink color. After each titration, carefully rinse the electrode with small portions of ethanol total of 15 mL to remove traces of oil or fat, followed by washing with distilled water, and immerse the electrode in distilled water for 1 min to rehydrate the meghod membrane.


Recently a green visual titrimetric method was presented for the determination of the acid number of oils and fats, using as titrant an aqueous 0. Table 1 officiall the acid numbers obtained for swine lard and for the vegetable oils canola, sunflower, linseed, castor, corn and soy applying the AOCS Cd 3d, the ABNT-NBRthe green visual 25 and the proposed potentiometric methods.

The sample is dissolved in a odficial mixture 1: This non aqueous potentiometric titration presents as a disadvantage the use of organic solvents that, besides the toxicological and environmental problems of the solvents, also causes the dehydration of the glass membrane of the electrode. A green potentiometric method for determination acs the acid number of oils and fats.

aocs official method cd 3d-63 pdf

The sample is then added and the obtained solution is titrated under vigorous shaking throughout until the moment a pink color that persists for 30 s is observed. Potentiometrically titrate with 0. This can be attributed to the fact that it is more difficult to determine the end point of the titration with the official method than in the other cases.

Analytical procedures Green 3-63 method Weight with at least 0. The membrane must be frequently rehydrated or the electrode can be irreversibly damaged. With respect to the precision of the methods, it is clear that the green potentiometric procedure herein proposed presents the best performance. Soy, corn, canola, sunflower, linseed and castor oils and swine lard used in the present study were purchased at local markets.