Complexometric determination of gallium with calcein blue as indicator.
A metalfluorechromic indicator, Calcein Blue, has been used for the back-titration of milligram amounts of EDTA in presence of gallium complexes. The indicator was used in conjunction with an ultraviolet titration assembly equipped with a cadmium sulphide detector cell and a microammeter for enhanced end-point detection. The result is a convenient and rapid method with an accuracy approaching 0.1% and a relative standard deviation of about 0.4% for 10 mg of gallium.
Elsheimer
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U.S. Geological Survey, Menlo Park, California 94025, U.S.A.