by year there has been an ever-mounting tempo in scientific research. More and more workers have been attracted to this field of endeavor, more and more laboratories have been established, more
VOLUME19, NO. 12 some specific applications for the determination of iron in solutions of high pH.
RECOMMENDED PROCEDURESample. Procure a representative portion of the material and subject it to the necessary preparative treatment. By weight or volume, measure the quantity of sample which contains not more than 6 mg. of iron. Dissolve the sample, if necessary, by appropriate means.Remove those substances which precipitate at pH's greater than 9.5 and check the interference of other ions present, Dilute to 100 ml. Desired Constituent. To a 50-ml. volumetric flask containing a 5-ml. aliquot of the sample, add 3 ml. of the reducing agent (the reducing agent is prepared by dissolving 10 grams of sodium dithionite in 100 ml. of concentrated ammonia and 50 ml. of water. Use of 0.1 to 0.4 grams of the solid sodium dithionite and the subsequent addition of 2 ml. ammonia is more desirable, if an iron-free salt is available) and 0.5 ml. of 1% butanedionedioxime or diethylaminobutanedionedioxime. (Two milliliters of a 0.2% ethanolic solution of 1,2-cyclohexanedionedioxime may be substituted if 6 ml. of the ammoniacal dithio-nite are used, and if transmittancy readings are taken at 543 my.) Allow this to stand for 15 minutes, dilute to volume, and take the transmittancy reading at 529 my for the former and 541 my for the latter reagent. A 30 my spectral band, with these wave lengths at the center, may be used. A method of visual comparison may be used, since these systems obey Beer's law.
LITERATURE CITED(1) Bachman, G. B., and Welton, D., private communication.(2) Diehl, H. C., "Applications of the Dioximes to Analytical Chemistry," Columbus, Ohio, G. Frederick Smith Chemical
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