Determination of metals in organometallic compounds by flame spectroscopic techniques
In the first part of the present work a general method has been developed for the determination of metals in organometallic compounds by using flame emission and atomic absorption techniques. This consists merely of dissolving the organometallic compound in a mixed aqueous organic solvent and aspirating the solution directly into the flame rather than by first decomposing the compound and then separating the metal, as is the normal procedure. The method has been applied to tin, antimony and molybdenum and a variety of organometallic compounds of these metals have been successfully analysed. The method has proved simple, precise and satisfactorily accurate. In the second part of the work the effect of organic solvents on tin absorption in air-hydrogen flames has been investigated. Generally it has been reported in the literature that organic solvents severely depress the tin absorption in air-hydrogen flames whereas in the present studies the effect found depended very much on the fuel/oxidant ratio of the flame. It was found that solvents increased the tin absorption in fuel-lean flames while in fuel-rich flames they depressed it. In between these two extremes the nature of the effect depended upon the solvent concentration in the sample solution. In this part of the work too, an attempt was made to explore the facts behind these surprising changes. The work includes the study of the effect on other metals and flames, spectroscopic measurements of various radicals in the flame including CH, C2 and H etc. and gas chromatographic analysis of the flame gases. On the basis of the evidence found in this part of the investigation it has been concluded that the depressive effect of organic, solvents on tin absorption is due to the depletion of active hydrogen atoms by the organic radicals produced from the pyrolysis of organic solvent molecules in the flame.