Premium
The autoxidative contraction of monolayers of linoleic acid at a gas‐water interface
Author(s) -
Porter W. L.,
Henick A. S.,
Clifford M.
Publication year - 1967
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/bf02545262
Subject(s) - autoxidation , monolayer , chemistry , contraction (grammar) , linoleic acid , oxygen , butylated hydroxyanisole , hydroquinone , organic chemistry , antioxidant , biochemistry , fatty acid , medicine
A monolayer of linoleic acid spread at an airwater interface was found to undergo an immediate oxygen‐dependent contraction when compressed at a constant high film pressure. This is in contrast to the expansion of monolayers of other unsaturated acids at lower film pressures as reported by other workers. The process shows quasi‐first‐order kinetics, and there is little evidence for an induction period, in contrast to bulk‐phase autoxidation. Initial rate of contraction is a function of pH between 6 and 9. This and other data suggest that contraction is due to the titration of the packed adjacent carboxyl groups in the monolayer and to the solution of short‐chain soaps resulting from the oxidative scission of linoleic acid. Although complete anaerobiasis prevented film contraction, neither dl ‐alpha‐tocopherol deposited in the film, nor hydroquinone in the substrate solution were inhibitory alone. Butylated hydroxyanisole (BHA) present in an aerobic gas phase produced inhibition of contraction of linoleic acid films spread on completely deaerated substrates. Inhibition was released upon removal of the BHA vapor, the restored rate in air approaching that before the BHA treatment. A method of specific testing of antioxidants is thus provided, which will differentiate between those presented in the vapor, the lipid, or the solution phases.