An iodometric method for peroxide determination has been modified and extensively tested. The modified method accurately determines peroxides present in autoxidized olefins but, in common with all other methods, it gives only empirical results when applied to peroxides formed in conjugated diolefins,

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The colorimetric ferrous thiocyanate method, first proposed by Young, Vogt, and Nieuwland, has been tested on a variety of autoxidized materials. It was found fundamentally accurate on hydrocarbon materials containing no conjugated diolefins; on diolefins the results varied considerably with time and were therefore of only empirical value. The precision was relatively poor (approximately ± 5 to 10% Of the absolute value) but the method was sensitive to very small peroxide concentrations.Presence of FERROUS ion has been used extensively as a reducing agent for the determination of organic peroxides. * One of the common methods involving ferrous ion, originally proposed by Young, Vogt, and Nieuwland ( 7), comprises reduction of the sample in an acidified solution of ferrous thiocyanate in methanol followed by measurement of the depth of color of the ferric thiocyanate produced. Bolland, Sundralingam, Sutton, and Tristram (3) used this method with slight variations in rubber research, and Farmer et al. ( 3) based theoretical conclusions on results using this method. Lips, Chapman, and McFarlane (5) used a similar method with acetone as solvent in place of methanol.

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