Studies on bile pigments

Abstract

TESTS for bilirubin in the urine are unsatisfactory owing to their lack of sensi- tivity.Gmelin's test with nitric acid and Rosin's test with iodine, depending on the formation of green biliverdin or blue bilicyanin, are positive only in the presence of high concentrations of pigment and many modifications of these methods do not give much better results.The reason for this failure is the fact that biliverdin or bilicyanin is only a transitional stage of bilirubin oxidation, the final stage being represented by the pink choletelin which is formed more rapidly in the presence of smaller amounts of bilirubin.Yet it is just in cases of slight jaundice that the detection of small amounts of bilirubin is of particular diagnostic importance.Zins [1923] modified Steensma's method by adsorbing the pigment on BaSO4 and testing the precipitate on the filter-paper with trichloroacetic acid.Cole [1926] described a modification of Huppert's method, adsorbing bilirubin on BaSO4, eluting the pigment with acid alcohol and oxidising it with KCIO3.Kuhn [1928] performs the oxidation by an alkaline copper solution and extracts the biliverdin in a layer of alcohol on the top.A spectroscopical test after oxidation of bilirubin to bilicyanin is described by Beccari [1928].Itallie [1929] devised a modification of Steensma's method, adsorbing the pigment on talc, eluting it with acid alcohol and oxidising it with NaNO3.Recently Godfried [1934] described a test devised by Harrison who adsorbs the pigment on BaSO4 and tests the precipitate on the filter with a drop of Fouche's reagent.EXPERIMENTAL.