Date of Award

Spring 1958

Document Type

Thesis - Restricted

Degree Name

Master of Science (MS)




In the last few years, much attention has been directed towards the use of organic chelating reagents in the determination of metals. Metal chelates are usually quite stable compounds of definite composition, insoluble in water and soluble in organic reagents. They are often highly colored. Furthermore, the reaction of an organic reagent with a metal under a given set of conditions may be quite specific or selective. Such properties explain the wide use of organic reagents in colorimetric and spectrophotometric analysis. Two main steps of any chemical analysis are: first, separation of the desired constituent, and second, the determination of the amount or concentration of this constituent. The process of solvent extraction may permit an easy, rapid, and clean separation of one or more elements from interferences. Photometric methods (analyses based upon the measurement of the amount of light absorbed by a colored solution) offer a practical method for determining traces of elements, often being far more rapid and accurate than the corresponding gravimetric and volumetric procedures. Combined extraction photometric procedures using an organic reagent should therefore offer enhanced possibilities for the determination of a desired constituent in the presence of relatively large amounts of interferences. Toluene-3, 4-dithiol (dithiol) is an organic chelating reagent for various metals. Its use as a reagent for tin has been established. Although papers have been published concerning a colorimetric (spectrophotometric) method for the determination of molybdenum and tungsten in steel or in organic materials, the conditions of the reaction have not been examined critically, nor is there agreement among the various authors as to the nature and extent of the interferences. As molybdenum and tungsten are two fairly common constituents of alloy steels, there would seem to be a need for a studied and reliable method for their determination in such materials. This problem is the basis of this research.



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