title: Cyclic peroxides and the thiobarbituric assay.
abstract: Several monocyclic peroxide compounds and two acyclic hydroperoxides have been tested for activity in the thiobarbituric acid test. All cyclic peroxides tested which have beta dioxygen functionality on non-tertiary carbons gave positive thiobarbituric acid tests at 532 nm. (epsilon = 10(3) --10(4)) Two acyclic unsaturated hydroperoxides which were derived from gamma-linolenic acid also gave positive thiobarbituric acid tests. In addition to the 532-nm-absorbing species, all peroxidic compounds tested showed a transient absorption at 450 nm during the thiobarbituric acid test. The species responsible for this 450 nm absorption appears to be an intermediate in a series reaction sequence. This intermediate is converted, in time, to the 532-nm-absorbing species. Thiobarbituric acid assay of the crude autoxidation product mixture of gamma-linolenic acid also shows this transient 450-nm-absorbing species. Added ferric ion enhances the 532 nm abosrbance of the thiobarbituric acid assay of cyclic peroxides.
mesh_terms: D008722:Methods; D010545:Peroxides / Q000032:analysis*; D013053:Spectrophotometry; D013056:Spectrophotometry, Ultraviolet; D013329:Structure-Activity Relationship; D013858:Thiobarbiturates
chemical_list: D010545:Peroxides; D013858:Thiobarbiturates