When a metal complex is synthesized, the quantitative determination of metal elements has been made by several methods, such as spectrometry, complexometric titration and gravimetric methods. However, it is difficult to prepare clear solution for spectrometry or complexometric titration, if the metal complex has a low solubility. In such a case, the gravimetric method will be applicable instead, however, it consumes fairly large amount of the precious sample for each analysis. Therefore, quantitative analyses of the metal elements in metal complexes are not so easy and common as the organic elementary analyses.
For the quantitative analyses of metal elements, atomic absorption spectrometry is considered to be one of the best methods.
The authors attempted to employ atomic absorption spectrometry to the analyses of metal elements in metal complexes. In this paper, analyses of the glycine, oxine-5-sulfonic acid, and oxine chelates of Zn, Cu, Ni, and Co as well as the acetates of these metals were carried out under the conditions shown in Table II. From these investigations, measurements of water soluble metal complexes are recommended to be carried out in acidic medium, for example 0.1
N HCl solution. In the case of water insoluble complexes, it is better to dissolve them in either alcohol or other organic solvents, in which the complexes are soluble. The sample solutions of Cu, Ni, and Co complexes were made to be
ca. 5 ppm in 0.1
N HCl and for Zn complexes
ca. 0.5 ppm solution was used. The commercial standard solutions of Cu, Ni, Co, and Zn were diluted to make the working curves.
The advantages of the present method are as follows: (1) A very small amount of the sample is quite enough for the measurements, (2) the pretreatment is simple, (3) the sensitivity is high.
Therefore, the atomic absorption spectrometry is recommended to the quantitative analyses of metal elements in metal complexes.
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