1) A new colorimetric method for the determination of methionine sulfoxide and its derivatives on the basis of the rearrangement of sulfoxide by the action of acetic anhydride has been established. 2) From about 10 μ to 80 μ mol. of methionine sulfoxide can be determined with an experimental error of 3 per cent. 3) The interference with the reaction by various amino acids and related substances has been investigated. 4) Several ...
