Premium
Colorimetric and potentiometric determination of acid numbers of vegetable and marine oils
Author(s) -
Ames Stanley R.,
Licata S. B.
Publication year - 1948
Publication title -
journal of the american oil chemists' society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.512
H-Index - 117
eISSN - 1558-9331
pISSN - 0003-021X
DOI - 10.1007/bf02645891
Subject(s) - potentiometric titration , phenolphthalein , chemistry , titration , solvent , benzene , anhydrous , chromatography , electroanalytical method , distillation , acid value , organic chemistry , biochemistry , ion
Summary A discussion is presented of present official methods of determining the acid number of oils. A colorimetric method is presented for the determination of acid numbers of marine and vegetable oils and related products. It involves the use of alcoholic KOH, phenolphthalein, and a titration solvent consisting of 49.5% anhydrous isopropanol. 50% benzene, and 0.5% water. Most oils are completely soluble in the titration solvent, thus avoiding the disadvantages of two phase systems and of heating the oil. It compares satisfactorily with present official methods. A potentiometric method which is at present an A.S.T.M. Standard Method for petroleum products is discussed. It has proved to be satisfactory for use with marine and vegetable oils. A close correspondence has been shown with a number of different oils between acid numbers obtained colorimetrically and potentiometrically. This makes it possible to compare directly results obtained by the two methods.